@article{myers_engman_ramirez_torres-molinari_lynch_eaton_cooney_kwak_2024, title={The effects of flow extremes on native and non-native stream fishes in Puerto Rico}, volume={7}, ISSN={["1365-2427"]}, url={https://doi.org/10.1111/fwb.14306}, DOI={10.1111/fwb.14306}, abstractNote={Abstract Globally, freshwater fishes are among the taxa most vulnerable to climate change but are generally understudied in tropical island ecosystems where climate change is predicted to alter the intensity, frequency and duration of extreme flow events. These changes may impact stream ecosystems and native and non‐native biota in complex ways. We compiled an extensive dataset of fish assemblages collected at 119 sites across the Caribbean island of Puerto Rico from 2005 to 2015. We coupled these data with stream flow indices and dam height to understand associations between flow and fish assemblage structure. Sixteen percent of sites contained exclusively non‐native species, 34% contained exclusively native species, and 50% contained native and non‐native species. We built generalised linear models and conducted all subsets model selection to identify extreme flow variables explaining variation in native and non‐native species richness and biomass. We also built models to determine the combined effects of extreme flows and the presence of non‐native species on native species richness and biomass. Extreme flows and dam height were important in explaining variations in native and non‐native species richness and biomass. Model averages showed native biomass decreased by 0.42 kg/ha with a 1‐m increase in dam height, by 0.05 kg/ha with 1 cm/s increase in maximum mean daily high flow and by 3.45 kg/ha with each additional day increase in maximum high flow duration, and increased by 2.06 kg/ha with each additional day increase in mean high flow duration. Model averages predicted that non‐native biomass increased by 1.32 kg/ha with a 1‐m increase in dam height and by 0.01 kg/ha with each additional day increase in mean high flow duration, and decreased by 0.36 kg/ha with each additional day increase in maximum high flow duration. Model averages also predicted an increase in native and non‐native biomass of 0.71 gage and 0.06 kg/ha, respectively, with each additional day increase in maximum low flow duration. The combined effects of non‐native species presence and extreme flows changed the relationship between maximum high and low flow durations and native biomass. Model averages showed that native biomass increased by 1.83 kg/ha with each additional day increase in maximum high flow duration and decreased by 2.52 kg/ha with each additional day increase in maximum low flow duration when non‐native species were present. Native fishes may be able to better cope with longer maximum durations of low flows than expected when non‐native fishes are absent. In mixed fish assemblages, extended maximum durations of high flows may act as a control of non‐native species and dampen their negative effect on native species, but longer maximum durations of low flows may heighten the negative effects of non‐native fishes. Our results are informative for tropical island ecosystems globally and can guide the management and conservation of native fishes, particularly when faced with the dual threats of climate change and non‐native species. Managers may consider increasing efforts to conserve native fishes in Caribbean rivers by maintaining connectivity and habitat complexity while preventing non‐native species introductions.}, journal={FRESHWATER BIOLOGY}, author={Myers, Bonnie J. E. and Engman, Augustin C. and Ramirez, Alonso and Torres-Molinari, Ambar and Lynch, Abigail J. and Eaton, Mitchell J. and Cooney, Patrick B. and Kwak, Thomas J.}, year={2024}, month={Jul} }
 @article{pandolfo_cope_weaver_kwak_hoeksema_2024, title={Thermal Threats to Freshwater Mussels: An Empirical Stream Assessment}, volume={16}, ISSN={["1424-2818"]}, url={https://doi.org/10.3390/d16010037}, DOI={10.3390/d16010037}, abstractNote={Freshwater mussels fulfill an important ecological role in aquatic ecosystems, but they currently face many threats, including thermal regime alteration. Thermal transformation of the aquatic environment is associated with climate change, land use alteration, and other pervasive anthropogenic global changes. To enhance our understanding of ecological thermal impacts, we combined extensive field measurements of temperature in the stream water column and substrate depths (5 and 15 cm) at sites where mussels occur, measures of abundance and species richness for mussels and fish, and thermal tolerance knowledge for mussels and fish to generate a comprehensive assessment of the potential threats mussels face as temperatures continue to rise as a result of global change. Mean summer (June–August 2010–2012) temperatures at mussel-occupied sites in the upper Tar River basin of North Carolina, USA, ranged from 16.2 to 34.7 °C. The mean temperature from the hottest 96 h at each site ranged from 23.5 to 31.5 °C. At 80% of sites, a period of moderate drought coincided with the hottest 96 h period. Temperature threshold exceedance durations indicated that chronic, combined chronic/acute, and acute freshwater mussel thermal tolerance thresholds (i.e., 28 °C, 30 °C, and 33 °C, respectively) based on laboratory exposures of glochidia (larvae) and juveniles were commonly exceeded. Water temperatures exceeded 28 °C for at least 24 h at 55% of sites and for at least 96 h at 35% of sites, and they exceeded 30 °C for at least 24 h at 15% of sites. We quantified a thermal buffering effect of the substrate that may be protective of mussels. There was a mean difference of 0.5 °C between the water column and the upper substrate (5 cm) and a mean difference of 0.9 °C between the water column and the lower substrate (15 cm). Maximum differences of up to 5.5 °C between the water column and the upper substrate and 11.5 °C between the water column and the lower substrate were observed. Our models estimating the relation between the water column and substrate temperatures more realistically characterize ambient temperature exposures and have widespread implications for mussel conservation and climate change risk assessment in similar streams. Freshwater mussels currently exist on the edge of their thermal limits, but their abundance and species richness cannot be explained by temperature patterns alone. Fish species richness was related to the thermal regime, indicating that species interactions may be an important driver of freshwater mussel responses to global change.}, number={1}, journal={DIVERSITY-BASEL}, author={Pandolfo, Tamara J. and Cope, W. Gregory and Weaver, Daniel M. and Kwak, Thomas J. and Hoeksema, Bert W.}, year={2024}, month={Jan} }
 @article{mciver ii_cope_bringolf_kwak_watson_maynard_mair_2023, title={Assessing the Toxicity of Sea Salt to Early Life Stages of Freshwater Mussels: Implications for Sea Level Rise in Coastal Rivers}, volume={9}, ISSN={["1552-8618"]}, DOI={10.1002/etc.5731}, abstractNote={AbstractSea levels across the planet are rising, particularly along the eastern coast of the United States. Climate‐induced sea level rise can result in the inundation and intrusion of seawater into freshwater drainages. This would alter salinity regimes and lead to the salinization of coastal freshwater ecosystems. Increased salinity levels in freshwater can negatively affect freshwater‐dependent species, including native mussels belonging to the order Unionida, which are highly sensitive to changes in water quality. Sea salt is largely made up of sodium and chloride ions, forming sodium chloride, a known toxicant to freshwater mussels. However, sea salt is a mixture that also contains other major ions, including potassium, sulfate, calcium, strontium, and magnesium, among others. Freshwater mussels exposed to sea salt would be exposed to each of the sea salt ions at the same time, resulting in a mixture toxicity effect. The mixture toxicity of these ions on early life stages of freshwater mussels is largely unknown because most research to date has evaluated individual salt ions in relative isolation. Therefore, we conducted acute toxicity tests on early life stages (glochidia and juvenile) of three freshwater mussel species that inhabit Atlantic Slope drainages (nonsalinity‐adapted Atlanticoncha ochracea, salinity‐adapted A. ochracea, Sagittunio nasutus, and Utterbackiana implicata). Glochidia and juveniles of each species were exposed to a control and six concentrations of Instant Ocean® Sea Salt (IOSS), a synthetic sea salt that closely resembles the ionic composition of natural sea salt. Exposure concentrations were 1 part(s) per thousand (ppt), 2 ppt, 8.5 ppt, 12.5 ppt, 17 ppt, and 34 ppt. We calculated the median effect concentration (EC50) for each of the eight acute toxicity tests and found that glochidia were more sensitive than juveniles to IOSS. At hour 24 EC50s for the glochidia ranged from 0.38 to 3.6 ppt, with the most sensitive freshwater mussel being the nonsalinity‐adapted A. ochracea, exhibiting an EC50 of 0.38 ppt (95% confidence interval [CI] 0.33–0.44). Juvenile freshwater mussels exhibited EC50s at hour 96 ranging from 5.0 to 10.4 ppt, with the least sensitive freshwater mussel being the nonsalinity‐adapted A. ochracea, exhibiting an EC50 of 10.4 ppt (95% CI 9.1–12.0). Our results show that acute exposure to sea salt adversely affects freshwater mussel viability, particularly glochidia. This information can be used to enhance freshwater mussel conservation strategies in regions that are or will be impacted by climate‐induced sea level rise and associated freshwater salinization. Environ Toxicol Chem 2023;42:2478–2489. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Mciver II, Joseph K. and Cope, W. Gregory and Bringolf, Robert B. and Kwak, Thomas J. and Watson, Brian and Maynard, Amy and Mair, Rachel}, year={2023}, month={Sep} }
 @article{favrot_kwak_2023, title={Habitat niche dynamics of the sicklefin redhorse: a southern Appalachian Mountain habitat specialist}, ISSN={["1573-5133"]}, DOI={10.1007/s10641-023-01465-3}, abstractNote={AbstractHistorically, suckers (Catostomidae) have been largely neglected in conservation efforts. Due to pervasive lotic habitat degradation and loss throughout North America, sucker habitat knowledge is urgently needed for conservation. The sicklefin redhorse (Moxostoma sp.) is an undescribed, imperiled sucker, endemic to a small geographic range in the southern Appalachian Mountains (USA). We described adult sicklefin redhorse seasonal and spawning microhabitat suitability, quantified spawning substrate composition, identified seasonal and spawning habitat niches (i.e., macrohabitats), and characterized foraging habitat. We combined radiotelemetry and visual observations of Hiwassee River basin adult sicklefin redhorses during March–January (2006–2008) to address our objectives. Sicklefin redhorses occupied seasonal and spawning microhabitats non-randomly, and we developed season- and spawning-specific habitat suitability criteria (HSC) using a Bayesian approach. Adult sicklefin redhorses occupied habitats with swift midchannel currents, moderate depths, and coarse substrates supporting hornleaf riverweed (Podostemum ceratophyllum). In contrast, suitable spawning sites were located in near-bank shallow depths, slow currents, over intermediate-sized substrates near cover, but free of riverweed. Annually, principal component analyses indicated that sheet and run macrohabitats were predominantly occupied, while pocket-water riffles near depositional, edgewater zones provided spawning sites. Spawning substrate composition was predominantly small cobble (40.9%) and very coarse gravel (21.3%), but fines (3.0%) were also prevalent within interstitial spaces. Mean Fredle index was 28.2, indicating spawning substrate permeability at half potential. Annually, bedrock covered with hornleaf riverweed was the dominant foraging substrate. Our adult sicklefin redhorse annual, seasonal, and spawning HSCs, multivariate habitat niche characterizations, spawning substrate analyses, and foraging habitat descriptions can guide habitat conservation and restoration throughout the species’ geographic range.}, journal={ENVIRONMENTAL BIOLOGY OF FISHES}, author={Favrot, Scott D. and Kwak, Thomas J.}, year={2023}, month={Sep} }
 @article{ulmo-diaz_engman_mclarney_alcala_hendrickson_bezault_feunteun_prats-leon_wiener_maxwell_et al._2023, title={Panmixia in the American eel extends to its tropical range of distribution: Biological implications and policymaking challenges}, ISSN={["1752-4571"]}, DOI={10.1111/eva.13599}, abstractNote={AbstractThe American eel (Anguilla rostrata) has long been regarded as a panmictic fish and has been confirmed as such in the northern part of its range. In this paper, we tested for the first time whether panmixia extends to the tropical range of the species. To do so, we first assembled a reference genome (975 Mbp, 19 chromosomes) combining long (PacBio and Nanopore and short (Illumina paired‐end) reads technologies to support both this study and future research. To test for population structure, we estimated genotype likelihoods from low‐coverage whole‐genome sequencing of 460 American eels, collected at 21 sampling sites (in seven geographic regions) ranging from Canada to Trinidad and Tobago. We estimated genetic distance between regions, performed ADMIXTURE‐like clustering analysis and multivariate analysis, and found no evidence of population structure, thus confirming that panmixia extends to the tropical range of the species. In addition, two genomic regions with putative inversions were observed, both geographically widespread and present at similar frequencies in all regions. We discuss the implications of lack of genetic population structure for the species. Our results are key for the future genomic research in the American eel and the implementation of conservation measures throughout its geographic range. Additionally, our results can be applied to fisheries management and aquaculture of the species.}, journal={EVOLUTIONARY APPLICATIONS}, author={Ulmo-Diaz, Gabriela and Engman, Augustin and Mclarney, William O. and Alcala, Carlos A. Lasso and Hendrickson, Dean and Bezault, Etienne and Feunteun, Eric and Prats-Leon, Fernando L. and Wiener, Jean and Maxwell, Robert and et al.}, year={2023}, month={Nov} }
 @article{torres-molinari_engman_pacifici_dolloff_myers_kwak_2023, title={Patterns in longitudinal distribution of American Eel (Anguilla rostrata) population characteristics in rivers of Puerto Rico}, volume={7}, ISSN={["1365-2400"]}, DOI={10.1111/fme.12645}, abstractNote={AbstractAmerican Eel (Anguilla rostrata) population characteristics and distribution remain drastically understudied in the Caribbean region. We conducted the first island‐wide study to evaluate the distribution of density, length, and sex in relation to distance from the mouth of 23 stream reaches in five rivers in Puerto Rico. We found 287 American Eel at a mean density of 156.7 fish/ha. Sex ratios favored females (52:3) but most of the eel sampled were undifferentiated or undetermined. Generalized linear modeling indicated that upstream habitats with low eel density were optimal environments for production of large and female eel. Our findings indicate that Puerto Rico could significantly contribute to the spawning population and strengthen knowledge of American Eel in the Caribbean. Our findings could be used to guide local and range‐wide conservation efforts to ensure stream connectivity and access to optimal upstream habitat for survival of the population.}, journal={FISHERIES MANAGEMENT AND ECOLOGY}, author={Torres-Molinari, A. and Engman, A. C. and Pacifici, K. and Dolloff, C. A. and Myers, B. J. E. and Kwak, T. J.}, year={2023}, month={Jul} }
 @article{lynch_myers_wong_chu_tingley_falke_kwak_paukert_krabbenhoft_2022, title={Reducing uncertainty in climate change responses of inland fishes: A decision-path approach}, volume={5}, ISSN={["2578-4854"]}, url={https://doi.org/10.1111/csp2.12724}, DOI={10.1111/csp2.12724}, abstractNote={AbstractClimate change will continue to be an important consideration for conservation practitioners. However, uncertainty in identifying appropriate management strategies, particularly for understudied species and regions, constrains the implementation of science‐based solutions and adaptation strategies. Here, we share a decision‐path approach to reduce uncertainty in climate change responses of inland fishes to inform conservation and adaptation planning. With the Fish and Climate Change database (FiCli), a comprehensive, online, public database of peer‐reviewed literature on documented and projected climate impacts to inland fishes, users can identify relevant studies and associated management recommendations via geographic regions, response types (i.e., fish assemblage dynamics, demographic, distributional, evolutionary, phenological), fish taxa, and traits (e.g., thermal guilds, feeding type, parental care, habitat type) and use a suite of summary tools to make more informed decisions. For both data‐rich and data‐poor scenarios, we demonstrate that this approach can reduce uncertainty in understanding climate change responses. Using thermal sensitivity as an example, we also establish the utility of FiCli database to address other user‐defined, management‐relevant questions via supplementary analyses. This decision‐path approach can be applied to rapid assessments, management decisions, and policy development and may serve as a model for other conservation decision‐making processes.}, journal={CONSERVATION SCIENCE AND PRACTICE}, author={Lynch, Abigail J. and Myers, Bonnie J. E. and Wong, Jesse P. and Chu, Cindy and Tingley, Ralph W. and Falke, Jeffrey A. and Kwak, Thomas J. and Paukert, Craig P. and Krabbenhoft, Trevor J.}, year={2022}, month={May} }
 @article{engman_kwak_fischer_2021, title={Big runs of little fish: first estimates of run size and exploitation in an amphidromous postlarvae fishery}, volume={78}, ISSN={["1205-7533"]}, DOI={10.1139/cjfas-2020-0093}, abstractNote={ Amphidromous postlarvae fisheries (APFs) constitute a globally widespread and distinctive class of fishery that is largely unknown to fisheries science. APFs harvest ocean-to-river migrating fishes at smaller sizes and younger ages than any other class of fishery. No quantitative estimates of run size and exploitation exist, which are needed to evaluate APF sustainability. Migrating amphidromous fishes are vectors of marine nutrients to estuaries and rivers, and run size quantification is needed to reveal the magnitude of this ecosystem function. We present a novel adaptation of trapezoidal area under the curve methods, which we apply in a Caribbean case study to yield the first simultaneous estimates of an APF run size and harvest. Run size estimates ranged 7.3–9.4 million postlarvae (926–1184 kg), and exploitation estimates (5.8%–7.0%) indicated low harvest in the Río Grande de Arecibo, Puerto Rico. Our representative run size estimates reveal that amphidromous postlarvae transport hundreds of kilograms of biomass per month to an estuary and river, the first empirical evidence that amphidromous migrations are large-magnitude material subsidies of lotic ecosystems. }, number={7}, journal={CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES}, author={Engman, Augustin C. and Kwak, Thomas J. and Fischer, Jesse R.}, year={2021}, month={Jul}, pages={905–912} }
 @article{porath_kwak_neely_shoup_2021, title={Catfish 2020, A Clear Vision of the Future}, volume={41}, ISSN={["1548-8675"]}, url={https://doi.org/10.1002/nafm.10688}, DOI={10.1002/nafm.10688}, abstractNote={AbstractThe Third International Catfish Symposium was held in Little Rock, Arkansas, in 2020 and provided another milestone to gauge advances in knowledge related to conservation and management of these valuable fishes. Attendees from 29 states and 4 countries gathered to communicate research and information on the conservation, ecology, and management of the world’s catfishes. During 3 d of technical sessions and workshops, 74 oral presentations and 17 posters were shared with 198 attending fisheries professionals. Plenary and oral presentations were recorded and are available online (https://www.youtube.com/channel/UCHNt7ZV05DLWoe4qJO798Pw/videos), aligning with the symposium theme of “Communicating Catfish Science.” Technical sessions explored current research and management issues that included population demographics, introduced catfish populations, sampling methods, harvest management, human dimensions, conservation, habitat use and movement, biology, and aging methods. Ultimately, 38 manuscripts were peer reviewed and published as this special issue of the North American Journal of Fisheries Management. Interest in catfish science, as gauged by publications in six peer‐reviewed fisheries journals, has grown steadily since a 1910 catfish aquaculture article appeared in the Transactions of the American Fisheries Society. Biology and ecology topics became prominent in the 1970s and 1980s, while articles on techniques and fisheries management have grown steadily through 2020. Ecology, fisheries management, and techniques were the most published topics in the three international catfish symposia. Future research and management efforts will continue similar work but also seek to address the expanding role of catfish as invasive species and a better understanding of the ecology and conservation of small‐bodied native catfish. Among the greatest challenges will be adapting current tools and identifying future knowledge gaps as we experience a changing climate. This will require an enhanced understanding of transforming ecosystems and advanced adaptive management applications. The decadal occurrence of a dedicated symposium has served to summarize progress and focus future efforts to advance catfish science.}, number={S1}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, publisher={Wiley}, author={Porath, Mark T. and Kwak, Thomas J. and Neely, Ben C. and Shoup, Daniel E.}, year={2021}, month={Sep} }
 @article{cope_kwak_black_pacifici_harris_miller_raley_hallerman_2021, title={Genetic Structure and Diversity of the Endemic Carolina Madtom and Conservation Implications}, volume={41}, ISSN={["1548-8675"]}, url={https://doi.org/10.1002/nafm.10589}, DOI={10.1002/nafm.10589}, abstractNote={AbstractIdentification and conservation of genetic diversity within and among freshwater fish populations are important to better manage and conserve imperiled species. The Carolina Madtom Noturus furiosus is a small, nongame catfish that is endemic to the Tar and Neuse River basins of North Carolina. Genetic structure has not been studied in the species, and given recent population declines in both basins, identification of remaining genetic diversity within the species is vital for informing conservation efforts. To assess the status and trends of Carolina Madtom genetic structure, we analyzed genetic markers from 173 individuals to (1) define population genetic structure, (2) assess intra‐ and interbasin genetic differentiation in the Tar and Neuse River basins, and (3) present management implications to guide conservation efforts. Using 10 microsatellite primers developed for the related Yellowfin Madtom N. flavipinnis, we observed low genetic diversity in Carolina Madtoms. Genotype frequencies within samples were not in Hardy–Weinberg equilibrium, with a deficit of heterozygotes that could be due to family structure, inbreeding, or segregation of null alleles. Mean (±SD) M‐ratios for the Tar River (0.414 ± 0.117) and Neuse River (0.117 ± 0.102) basin collections indicated that both populations have experienced recent demographic bottlenecks, with that in the Neuse River basin population being more severe. Effective population size estimates for the respective populations were small, on the order of tens of individuals, driving low genetic diversity within populations. However, the multilocus population differentiation metrics  (mean ± SE = 0.135 ± 0.031) and DEST (0.125 ± 0.029) were significantly different from zero (P < 0.001), indicating significant genetic differentiation between the Tar and Neuse River basin populations. Our findings will inform managers on the status of genetic variation in the Carolina Madtom and will guide conservation toward protective listing and management decisions to maintain the viability of this important endemic species.}, number={S1}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, publisher={Wiley}, author={Cope, W. Robert and Kwak, Thomas J. and Black, Tyler R. and Pacifici, Krishna and Harris, Sheila C. and Miller, Caitlin M. and Raley, Morgan E. and Hallerman, Eric M.}, year={2021}, month={Oct}, pages={S27–S41} }
 @article{grieshaber_cope_kwak_penland_heise_mac law_2021, title={Survival and Contaminants in Imperiled and Common Riverine Fishes Assessed with an In Situ Bioassay Approach}, volume={40}, DOI={10.1002/etc.5104}, abstractNote={AbstractAn in situ bioassay approach was used to determine whether aquatic contaminant stressors in a large Atlantic river ecosystem affect the survival of 3 fish species: the largemouth bass (Micropterus salmoides, juveniles), the fathead minnow (Pimephales promelas, adults), and the robust redhorse (Moxostoma robustum, juveniles). Hatchery‐propagated fish were placed into cages to assess site‐specific survival in the Yadkin‐Pee Dee River of North Carolina and South Carolina, USA. Contaminants were measured in caged fish and sediment and surface water at each site. No apparent longitudinal trends in fish survival were detected, and contaminant concentrations varied among sites. Juvenile largemouth bass and robust redhorse did not survive past 13 and 23 d, with corresponding Kaplan‐Meier median survival estimates of 9.7 and 12.1 d, respectively. Survival of adult fathead minnows deployed in cages alongside the juvenile fish averaged 43% at the end of the 28‐d exposure, with a 22‐d median survival estimate. The intersex condition, an indicator of endocrine disruption, was not observed in any adult fathead minnow. Contaminant accumulation in surviving fathead minnows was apparent, with highest accumulated concentrations of polychlorinated biphenyls (34.6–93.4 ng/g dry wt), organochlorine pesticides (19.9–66.1 ng/g dry wt), and mercury (0.17–0.63 μg/g dry wt). Contaminants and other water quality stressors in this river system appear to detrimentally impact juvenile fish survival, with presumed effects at the fish assemblage and community levels. Environ Toxicol Chem 2021;40:2206–2219. © 2021 SETAC}, number={8}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Grieshaber, Casey A. and Cope, W. Gregory and Kwak, Thomas J. and Penland, Tiffany N. and Heise, Ryan J. and Mac Law, J.}, year={2021}, month={Jun}, pages={2206–2219} }
 @article{krabbenhoft_myers_wong_chu_tingley_falke_kwak_paukert_lynch_2020, title={FiCli, the Fish and Climate Change Database, informs climate adaptation and management for freshwater fishes}, volume={7}, ISSN={["2052-4463"]}, DOI={10.1038/s41597-020-0465-z}, abstractNote={AbstractInland fishes provide important ecosystem services to communities worldwide and are especially vulnerable to the impacts of climate change. Fish respond to climate change in diverse and nuanced ways, which creates challenges for practitioners of fish conservation, climate change adaptation, and management. Although climate change is known to affect fish globally, a comprehensive online, public database of how climate change has impacted inland fishes worldwide and adaptation or management practices that may address these impacts does not exist. We conducted an extensive, systematic primary literature review to identify peer-reviewed journal publications describing projected and documented examples of climate change impacts on inland fishes. From this standardized Fish and Climate Change database, FiCli (pronounced fick-lee), researchers and managers can query fish families, species, response types, or geographic locations to obtain summary information on inland fish responses to climate change and recommended management actions. The FiCli database is updatable and provides access to comprehensive published information to inform inland fish conservation and adaptation planning in a changing climate.}, number={1}, journal={SCIENTIFIC DATA}, author={Krabbenhoft, Trevor J. and Myers, Bonnie J. E. and Wong, Jesse P. and Chu, Cindy and Tingley, Ralph W., III and Falke, Jeffrey A. and Kwak, Thomas J. and Paukert, Craig P. and Lynch, Abigail J.}, year={2020}, month={Apr} }
 @article{penland_cope_kwak_strynar_grieshaber_heise_sessions_2020, title={Trophodynamics of Per- and Polyfluoroalkyl Substances in the Food Web of a Large Atlantic Slope River}, volume={54}, url={https://doi.org/10.1021/acs.est.9b05007}, DOI={10.1021/acs.est.9b05007}, abstractNote={Per- and polyfluoroalkyl substances (PFASs) have attracted scientific and regulatory attention due to their persistence, bioaccumulative potential, toxicity, and global distribution. We determined the accumulation and trophic transfer of 14 PFASs within the food web of the Yadkin-Pee Dee River of North Carolina and South Carolina, USA. Food web components and pathways were determined by stable isotope analyses of producers, consumers, and organic matter. Analyses of water, sediment, organic matter, and aquatic biota revealed that PFASs were prevalent in all food web compartments, with most detections and greatest concentrations in aquatic insects. All 14 PFASs were detected in individual aquatic insect samples (range, < limit of detection [<LOD] - 1,670 ng/g wet weight [WW]) and individual fish tissue samples (range, <LOD - 797 ng/g WW). Perfluorooctane sulfonate (PFOS) was the dominant PFAS among all samples (64%). The ova of an imperiled fish, the Robust Redhorse (Moxostoma robustum), had concentrations of 10 PFASs (range, <LOD - 483 ng/g WW) and PFOS concentration was exceptionally high (483 ng/g WW), indicating likely maternal transfer. Our findings demonstrate the prevalence of PFASs in a freshwater food web with potential implications for ecological and human health.}, number={11}, journal={Environmental Science & Technology}, publisher={American Chemical Society (ACS)}, author={Penland, Tiffany N. and Cope, W. Gregory and Kwak, Thomas J. and Strynar, Mark J. and Grieshaber, Casey A. and Heise, Ryan J. and Sessions, Forrest W.}, year={2020}, month={Jun}, pages={6800–6811} }
 @article{cope_kwak_black_pacifici_2019, title={Evaluation of Artificial Cover Units as a Sampling Technique and Habitat Enhancement for Madtoms in Rivers}, volume={39}, ISSN={["1548-8675"]}, url={https://doi.org/10.1002/nafm.10317}, DOI={10.1002/nafm.10317}, abstractNote={AbstractInstream habitat degradation and loss are major threats to freshwater fishes and critical conservation issues among nongame species due to a lack of research and knowledge concerning their habitat requirements. Instream physical cover is an important component of fish habitat, especially for benthic species that require cover for reproduction and shelter from predators. One such species is the Carolina Madtom Noturus furiosus, a small, imperiled, nongame catfish that is endemic to the Neuse and Tar River basins of North Carolina. To enhance understanding of instream cover dynamics, we constructed artificial cover units from terra cotta materials and deployed them in rivers to (1) evaluate whether they could be an effective passive‐sampling technique to estimate detection and occupancy of the Carolina Madtom and (2) determine their potential to enhance habitat in systems where instream cover has been lost. Artificial cover units were deployed at eight sites in the Neuse and Tar River basins, and the units collected 30 Carolina Madtoms at two sites in the Tar River basin. Occupancy modeling estimated a Carolina Madtom detection probability of 0.92 using artificial cover units. Compared to other standardized sampling methods, artificial cover units were an efficient passive‐sampling technique for detecting Carolina Madtoms. Observations also revealed that artificial cover units were occupied by Carolina Madtoms for reproduction. These findings provide an additional means by which natural resource managers can assess the status of this imperiled species via an inexpensive passive‐sampling device that can provide spawning habitat and protection from predators as well as helping to mitigate the effects of instream habitat degradation.}, number={4}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, publisher={Wiley}, author={Cope, W. Robert and Kwak, Thomas J. and Black, Tyler R. and Pacifici, Krishna}, year={2019}, month={Aug}, pages={778–787} }
 @article{engman_kwak_fischer_lilyestrom_2019, title={Fish Assemblages and Fisheries Resources in Puerto Rico's Riverine Estuaries}, volume={11}, ISSN={["1942-5120"]}, DOI={10.1002/mcf2.10072}, abstractNote={AbstractTropical estuaries are diverse and productive habitats with respect to their fish assemblages and associated fisheries, but these ecosystems and fisheries are imperiled by multiple anthropogenic threats. Despite the economic, social, and biodiversity value of tropical estuarine fish assemblages, they are poorly understood, especially those on Caribbean islands. We sampled the fish assemblages of four estuaries that were broadly representative of riverine estuaries in Puerto Rico, including the Río Grande de Arecibo, Río Espiritu Santo, Río Mameyes, and Río Sabana. We used a combination of passive (gill nets) and active (seine) gears at locations that spanned the salinity gradient of each estuary during July–October 2013–2014 (rainy season) and March 2015 (dry season). Fish species richness among the riverine estuaries varied from 18 to 29 and was highest in the Río Espiritu Santo estuary. Nonmetric multidimensional scaling differentiated fish assemblages among estuaries but not by season or consistently by location within an estuary. Spearman's rank correlation analysis also revealed dissimilarity among each estuary's fish assemblage, as most pairwise correlations between the species compositions were not significant. We identified common and widespread species among estuaries, including sport fishes, such as the Tarpon Megalops atlanticus and Common Snook Centropomus undecimalis. As the only multi‐river assessment of riverine estuary fish assemblages in Puerto Rico, our results provide the best available information about the spatial variability of assemblages and fisheries resources. This information will benefit future conservation and fisheries management efforts, which are needed due to increasing anthropogenic impacts, such as illegal harvest, invasive species, and water diversions.}, number={2}, journal={MARINE AND COASTAL FISHERIES}, author={Engman, Augustin C. and Kwak, Thomas J. and Fischer, Jesse R. and Lilyestrom, Craig G.}, year={2019}, month={Apr}, pages={189–201} }
 @article{fischer_kwak_flowers_cope_rash_besler_2019, title={Growth, Condition, and Trophic Relations of Stocked Trout in Southern Appalachian Mountain Streams}, volume={148}, ISSN={["1548-8659"]}, url={https://doi.org/10.1002/tafs.10170}, DOI={10.1002/tafs.10170}, abstractNote={AbstractStream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatchery‐reared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012–June 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic position with stable isotope analysis. Relative weights (Wr) of stocked trout were inversely associated with their stream residence time but were consistently higher than those of wild trout. Weight loss of harvested stocked trout was similar among species and sizes, but fish stocked earlier lost more weight. Overall, 40% of 141 stomachs from stocked trout were empty compared to 15% of wild trout stomachs (N = 26). We identified a much higher rate of piscivory in wild trout (18 times that of stocked trout), and wild trout were 4.3 times more likely to consume gastropods relative to stocked trout. Hatchery‐reared trout were isotopically similar to co‐occurring wild fish for both δ13C and δ15N values but were less variable than wild trout. Differences in sulfur isotope ratios (δ34S) between wild and hatchery‐reared trout indicated that the diets of wild fish were enriched in δ34S relative to the diets of hatchery‐reared fish. Although hatchery‐reared trout consumed prey items similar to those of wild fish, differences in consumption or behavior (e.g., reduced feeding) may have resulted in lower condition and negative growth. These findings provide critical insight on the trophic dynamics of stocked trout and may assist in developing and enhancing stream trout fisheries.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, publisher={Wiley}, author={Fischer, Jesse R. and Kwak, Thomas J. and Flowers, H. Jared and Cope, W. Gregory and Rash, Jacob M. and Besler, Douglas A.}, year={2019}, month={Jul}, pages={771–784} }
 @article{engman_hogue_starnes_raley_kwak_2019, title={Puerto Rico Sicydium goby diversity: species-specific insights on population structures and distributions}, volume={5}, ISSN={["2376-6808"]}, DOI={10.1080/23766808.2019.1606669}, abstractNote={ABSTRACT Sicydiine gobies are major contributors to Caribbean stream fish biodiversity, and ecosystem functions and services. In the Caribbean, Sicydiine gobies are represented by a single genus, Sicydium, but species-level Sicydium taxonomy and distributions remain unresolved in this region. A previous study posited that four species of Sicydium are present in Puerto Rico, including the recently described Sicydium gilberti; however, that study relied solely on morphological characters, and samples from a limited number of locations. Identification of Sicydium to species in studies with more comprehensive sampling has not occurred due to the impracticality of field identification. In our study, we employed morphological data and Mitochondrial Cytochrome C Oxidase I (mtCOI) genetic sequence data, collected from over 500 Sicydium spp. individuals at 16 broadly distributed sites, to provide an inventory of the species of Sicydium that occur in Puerto Rico. Additionally, we reveal new information on the spatial patterns of distribution, relative abundance, population structure, and observed molecular diversity among Sicydium taxa in Puerto Rico’s river systems. This information is essential to advance ecological and evolutionary knowledge of Caribbean fish assemblages, guide stream fish conservation, and to effectively manage fisheries.}, number={1}, journal={NEOTROPICAL BIODIVERSITY}, author={Engman, Augustin C. and Hogue, Gabriela M. and Starnes, Wayne C. and Raley, Morgan E. and Kwak, Thomas J.}, year={2019}, month={Apr}, pages={22–29} }
 @article{popp_cope_mcgregor_kwak_augspurger_levine_koch_2018, title={A Comparison of the chemical sensitivities between in vitro and in vivo propagated juvenile freshwater mussels: Implications for standard toxicity testing}, volume={37}, ISSN={0730-7268}, url={http://dx.doi.org/10.1002/etc.4270}, DOI={10.1002/etc.4270}, abstractNote={AbstractUnionid mussels are ecologically important and are globally imperiled. Toxicants contribute to mussel declines, and toxicity tests using juvenile mussels—a sensitive life stage—are valuable in determining thresholds used to set water quality criteria. In vitro culture methods provide an efficient way to propagate juveniles for toxicity testing, but their relative chemical sensitivity compared with in vivo propagated juveniles is unknown. Current testing guidelines caution against using in vitro cultured juveniles until this sensitivity is described. Our objective was to evaluate the relative sensitivity of juvenile mussels produced from both in vitro and in vivo propagation methods to selected chemicals. We conducted 96‐h acute toxicity tests according to ASTM International guidelines with 3 mussel species and 6 toxicants: chloride, nickel, ammonia, and 3 copper‐based compounds. Statistically significant differences between in vitro and in vivo juvenile 96‐h median effect concentrations were observed in 8 of 17 tests, and in vitro juveniles were more sensitive in 6 of the 8 significant differences. At 96 h, 4 of the 8 statistically different tests for a given chemical were within a factor of 2, which is the intralaboratory variation demonstrated in a recent evaluation of mussel toxicity tests. We found that although differences in chemical sensitivity exist between in vitro and in vivo propagated juvenile mussels, they are within normal toxicity test variation. Therefore, in vitro propagated juvenile mussels may be appropriate for use in ASTM International‐based toxicity testing. Environ Toxicol Chem 2018;37:3077–3085. © 2018 SETAC}, number={12}, journal={Environmental Toxicology and Chemistry}, publisher={Wiley}, author={Popp, Anakela and Cope, W. Gregory and McGregor, Monte A. and Kwak, Thomas J. and Augspurger, Tom and Levine, Jay F. and Koch, Leroy}, year={2018}, month={Nov}, pages={3077–3085} }
 @article{favrot_kwak_2018, title={Behavior and Reproductive Ecology of the Sicklefin Redhorse: An Imperiled Southern Appalachian Mountain Fish}, volume={147}, ISSN={["1548-8659"]}, DOI={10.1002/tafs.10010}, abstractNote={AbstractMany nongame fishes are poorly understood but are essential to maintaining healthy aquatic ecosystems globally. The undescribed Sicklefin Redhorse Moxostoma sp. is a rare, imperiled, nongame fish endemic to two southern Appalachian Mountain river basins. Little is known of its behavior and ecology, but this information is urgently needed for conservation planning. We assessed the spatial and temporal bounds of spawning migration, quantified seasonal weekly movement patterns, and characterized seasonal and spawning behavior using radiotelemetry and weir sampling in the Hiwassee River basin, North Carolina–Georgia, during 2006 and 2007. Hiwassee River tributaries were occupied predominantly during the fish's spawning season, lower reaches of the tributaries and the Hiwassee River were primarily occupied during the postspawning season (i.e., summer and fall), and lower lotic reaches of Hiwassee River (upstream from Hiwassee Lake) were occupied during winter. Adults occupied Hiwassee Lake only as a movement corridor during spawning migrations. Both sexes conducted upstream spawning migrations simultaneously, but males occupied spawning tributaries longer than females. Sicklefin Redhorse exhibited interannual spawning‐area and tributary fidelity. Cold water temperatures associated with hypolimnetic releases from reservoirs and meteorological conditions influenced spawning migration distance and timing. During 2007, decreased discharges during the spawning season were associated with decreases in migration distance and spawning tributary occupancy duration. Foraging was the dominant behavior observed annually, followed by reproductive behaviors (courting and spawning) during the spawning season. No agonistic reproductive behavior was observed, but females exhibited a repetitious postspawning digging behavior that may be unique in the family Catostomidae. Our findings suggest that protection and restoration of river continuity, natural flow regimes, seasonally appropriate water temperatures, and geographic range expansion are critical components to include in Sicklefin Redhorse conservation planning. Fisheries and ecosystem managers can use our findings to justify sensitive management decisions that conserve and restore critical streams and rivers occupied by this imperiled species.}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Favrot, Scott D. and Kwak, Thomas J.}, year={2018}, month={Jan}, pages={204–222} }
 @article{flowers_kwak_fischer_cope_rash_besler_2019, title={Behavior and Survival of Stocked Trout in Southern Appalachian Mountain Streams}, volume={148}, ISSN={["1548-8659"]}, DOI={10.1002/tafs.10113}, abstractNote={AbstractStocking of trout to support recreational fisheries is a common practice among state and federal agencies to meet angling and harvest demands. Success of stocking efforts relies upon fish behavior and survival to maximize the availability of fish to anglers. We quantitatively described the movement behavior and survival of stocked Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss in three southern Appalachian Mountain streams in western North Carolina, USA, that were managed under delayed harvest regulations. Hatchery trout were tagged with a combination of PIT tags and radio transmitters (radio tags); stocked into “Delayed Harvest Trout Waters” of the North Toe, East Prong Roaring, and Little rivers; and monitored during the catch‐and‐release season from October to June. Assessed according to river and species, 19–65% of trout emigrated from the delayed harvest study reaches, while 1–29% died within the reaches. The majority of radio‐tagged fish (71%; 59–85% by river) remained within 2 km of the stocking location, whereas 6% migrated over 10 km from the stocking location. Few trout stocked during fall (October and November) were available to anglers the following June due to a combination of migration and mortality. Emigration from delayed harvest study reaches was associated with stocking and high‐flow events. Multi‐state modeling detailed these observations with weekly estimates of migration and survival rates. River‐specific differences in emigration and mortality suggested that emigration was a greater source of trout loss than mortality in all rivers; no pattern related to river size was apparent in emigration, but mortality was greater in small streams. Brook Trout mortality rates were highest among the three species, and large fish of most species showed higher emigration and mortality than catchable‐sized trout. Fisheries managers can apply our results to alter stocking regimes so as to enhance the efficiency of stocking and the acclimation of stocked trout to instream environments.}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Flowers, H. Jared and Kwak, Thomas J. and Fischer, Jesse R. and Cope, W. Gregory and Rash, Jacob M. and Besler, Douglas A.}, year={2019}, month={Jan}, pages={3–20} }
 @article{archambault_cope_kwak_2018, title={Chasing a changing climate: Reproductive and dispersal traits predict how sessile species respond to global warming}, volume={24}, ISSN={["1472-4642"]}, url={https://doi.org/10.1111/ddi.12740}, DOI={10.1111/ddi.12740}, abstractNote={AbstractAimStudies of species' range shifts have become increasingly relevant for understanding ecology and biogeography in the face of accelerated global change. The combination of limited mobility and imperilled status places some species at a potentially greater risk of range loss, extirpation or extinction due to climate change. To assess the ability of organisms with limited movement and dispersal capabilities to track shifts associated with climate change, we evaluated reproductive and dispersal traits of freshwater mussels (Unionida), sessile invertebrates that require species‐specific fish for larval dispersal.LocationNorth American Atlantic Slope rivers.MethodsTo understand how unionid mussels may cope with and adapt to current and future warming trends, we identified mechanisms that facilitated their colonization of the northern Atlantic Slope river basins in North America after the Last Glacial Maximum. We compiled species occurrence and life history trait information for each of 55 species, and then selected life history traits for which ample data were available (larval brooding duration, host fish specificity, host infection strategy, and body size) and analysed whether the trait state for each was related to mussel distribution in Atlantic Slope rivers.ResultsBrooding duration (p < .01) and host fish specificity (p = .02) were significantly related to mussel species distribution. Long‐term brooders were more likely than short‐term brooders to colonize formerly glaciated rivers, as were host generalists compared to specialists. Body size and host infection strategy were not predictive of movement into formerly glaciated rivers (p > .10).Main conclusionsOur results are potentially applicable to many species for which life history traits have not been well‐documented, because reproductive and dispersal traits in unionid mussels typically follow phylogenetic relationships. These findings may help resource managers prioritize species according to climate change vulnerability and predict which species might become further imperilled with climate warming. Finally, we suggest that similar trait‐based decision support frameworks may be applicable for other movement limited taxa.}, number={7}, journal={DIVERSITY AND DISTRIBUTIONS}, publisher={Wiley}, author={Archambault, Jennifer M. and Cope, W. Gregory and Kwak, Thomas J.}, editor={Ricciardi, AnthonyEditor}, year={2018}, month={Jul}, pages={880–891} }
 @article{engman_kwak_cope_2018, title={Do postlarval amphidromous fishes transport marine-derived nutrients and pollutants to Caribbean streams?}, volume={27}, url={https://doi.org/10.1111/eff.12397}, DOI={10.1111/eff.12397}, abstractNote={AbstractDiadromous fishes are known biotransport vectors that can move nutrients, energy and contaminants in an upstream direction in lotic ecosystems. This function has been demonstrated repeatedly in anadromous salmonids, but the role of other diadromous species, especially tropical taxa, as biotransport vectors is less studied. Amphidromous fish species exhibit potential to act as upstream vectors of nutrients and contaminants in their postlarval and juvenile stages, but this role is largely unknown because of limited understanding of larval growth habitats. Moreover, because some species are harvested in artisanal fisheries as postlarvae, and postlarvae are consumed by riverine and estuarine predators, heavy contaminant loads may present a human or wildlife health concern. This research incorporates stable isotope and contaminant analyses to infer larval habitats and contaminant accumulation of amphidromous fishes on the Caribbean island of Puerto Rico. The isotopic signatures of postlarval amphidromous fishes indicated marine basal sources and food web components, rather than those from riverine habitats. Additionally, postlarvae did not contain concentrations of anthropogenic pollutants that would be of ecological or human health concern. These findings are the first and strongest evidence that amphidromous fish postlarvae function as biotransport vectors of marine nutrients into and up river ecosystems without posing a health threat to the receiving food web or human consumers.}, number={3}, journal={Ecology of Freshwater Fish}, publisher={Wiley}, author={Engman, A. C. and Kwak, T. J. and Cope, W. G.}, year={2018}, month={Jul}, pages={847–856} }
 @article{kwak_engman_lilyestrom_2019, title={Ecology and conservation of the American eel in the Caribbean region}, volume={26}, ISSN={["1365-2400"]}, DOI={10.1111/fme.12300}, abstractNote={AbstractThe majority of American eel, Anguilla rostrata LeSueur, knowledge is derived from temperate regions in the United States and Canada, with little known from its tropical Caribbean distribution. Findings of original research on American eel distribution, abundance, population biology, habitat ecology and threats from the Caribbean island of Puerto Rico were synthesised. American eel were captured from 48 of 116 sites (41.4%) in 26 of 49 river basins (53.1%) during 2005–2016, and it was extirpated upstream of dams and migration barriers >3.0 m high (38.9% of habitat). Mean density and biomass were 438.9 fish/ha and 23.44 kg/ha, respectively. Upstream habitats favoured larger individuals, and females were larger than males. The swim‐bladder parasite Anguillicoloides crassus Kuwahara, Niimi & Hagaki was not found in 120 eels examined. Realised threats include dams and other migratory barriers, habitat loss and alteration and pollution; exotic species and commercial fishing are impending threats; and the least understood is climate change.}, number={1}, journal={FISHERIES MANAGEMENT AND ECOLOGY}, author={Kwak, Thomas J. and Engman, Augustin C. and Lilyestrom, Craig G.}, year={2019}, month={Feb}, pages={42–52} }
 @article{buczek_cope_mclaughlin_kwak_2018, title={Effects of Turbidity, Sediment, and Polyacrylamide on Native Freshwater Mussels}, volume={54}, ISSN={["1752-1688"]}, url={https://doi.org/10.1111/1752-1688.12639}, DOI={10.1111/1752-1688.12639}, abstractNote={AbstractTurbidity is a ubiquitous pollutant adversely affecting water quality and aquatic life in waterways globally. Anionic polyacrylamide (PAM) is widely used as an effective chemical flocculent to reduce suspended sediment (SS) and turbidity. However, no information exists on the toxicity of PAM‐flocculated sediments to imperiled, but ecologically important, freshwater mussels (Unionidae). Thus, we conducted acute (96 h) and chronic (24 day) laboratory tests with juvenile fatmucket (Lampsilis siliquoidea) and three exposure conditions (nonflocculated settled sediment, SS, and PAM‐flocculated settled sediment) over a range of turbidity levels (50, 250, 1,250, and 3,500 nephelometric turbidity units). Survival and sublethal endpoints of protein oxidation, adenosine triphosphate (ATP) production, and protein concentration were used as measures of toxicity. We found no effect of turbidity levels or exposure condition on mussel survival in acute or chronic tests. However, we found significant reductions in protein concentration, ATP production, and oxidized proteins in mussels acutely exposed to the SS condition, which required water movement to maintain sediment in suspension, indicating responses that are symptoms of physiological stress. Our results suggest anionic PAM applied to reduce SS may minimize adverse effects of short‐term turbidity exposure on juvenile freshwater mussels without eliciting additional lethal or sublethal toxicity.}, number={3}, journal={JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION}, author={Buczek, Sean B. and Cope, W. Gregory and McLaughlin, Richard A. and Kwak, Thomas J.}, year={2018}, month={Jun}, pages={631–643} }
 @article{penland_grieshaber_kwak_cope_heise_sessions_2018, title={Food web contaminant dynamics of a large Atlantic Slope river: Implications for common and imperiled species}, volume={633}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2018.03.251}, abstractNote={Persistent and bioaccumulative contaminants often reach concentrations that threaten aquatic life by causing alterations in organism behavior and development, disruption of biological processes, reproductive abnormalities, and mortality. The objectives of this research were to determine the aquatic food web structure and trophic transfer and accumulation of contaminants within a riverine ecosystem and identify potential stressors to the health of an imperiled fish, the robust redhorse (Moxostoma robustum) and other species of conservation concern in a large Atlantic Slope (USA) river. Trophic position was determined for food web taxa by stable isotope analyses of representative producers, consumers, and organic matter of the Yadkin-Pee Dee River of North Carolina and South Carolina. Contaminant analyses were performed on water, sediment, organic matter, and aquatic biota to assess the prevalence and accumulation of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), current use pesticides (CUPs), polycyclic aromatic hydrocarbons (PAHs), and selected metals. Contaminants were prevalent in the environment and food web components of the river. PCBs were detected in 32% of biotic samples (mean 0.24μg/g dry weight [DW], range 0.01-3.33μg/g DW), and DDTs (legacy OCPs and metabolites) were detected in 90% (mean 0.014μg/g DW, range 0.0004-0.29μg/g DW). The trace metals manganese and cadmium exceeded published threshold effect concentrations in sediment (460 and 0.99μg/g DW, respectively). Mercury was detected in all food web samples exhibiting a mean of 0.61μg/g DW and range 0.006-2.35μg/g DW (mean 0.13μg/g wet weight [WW], range 0.001-0.6μg/g WW). Concentrations exceeded the 0.2μg/g WW aquatic life criterion for mercury in 38% of fish samples. Fish trophic magnification factors (TMFs; range 0.33-3.75) indicated that contaminant accumulation occurred from both water and dietary sources. The combination of analytical approaches applied here provides new insight into contaminant dynamics with conservation implications.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Penland, Tiffany N. and Grieshaber, Casey A. and Kwak, Thomas J. and Cope, W. Gregory and Heise, Ryan J. and Sessions, Forrest W.}, year={2018}, month={Aug}, pages={1062–1077} }
 @article{drew_eddy_kwak_cope_augspurger_2018, title={Hydrologic characteristics of freshwater mussel habitat: novel insights from modeled flows}, volume={37}, ISSN={["2161-9565"]}, DOI={10.1086/697947}, abstractNote={The ability to model freshwater stream habitat and species distributions is limited by the spatially sparse flow data available from long-term gauging stations. Flow data beyond the immediate vicinity of gauging stations would enhance our ability to explore and characterize hydrologic habitat suitability. The southeastern USA supports high aquatic biodiversity, but threats, such as landuse alteration, climate change, conflicting water-resource demands, and pollution, have led to the imperilment and legal protection of many species. The ability to distinguish suitable from unsuitable habitat conditions, including hydrologic suitability, is a key criterion for successful conservation and restoration of aquatic species. We used the example of the critically endangered Tar River Spinymussel (Parvaspina steinstansana) and associated species to demonstrate the value of modeled flow data (WaterFALL™) to generate novel insights into population structure and testable hypotheses regarding hydrologic suitability. With ordination models, we: 1) identified all catchments with potentially suitable hydrology, 2) identified 2 distinct hydrologic environments occupied by the Tar River Spinymussel, and 3) estimated greater hydrological habitat niche breadth of assumed surrogate species associates at the catchment scale. Our findings provide the first demonstrated application of complete, continuous, regional modeled hydrologic data to freshwater mussel distribution and management. This research highlights the utility of modeling and data-mining methods to facilitate further exploration and application of such modeled environmental conditions to inform aquatic species management. We conclude that such an approach can support landscape-scale management decisions that require spatial information at fine resolution (e.g., enhanced National Hydrology Dataset catchments) and broad extent (e.g., multiple river basins).}, number={2}, journal={FRESHWATER SCIENCE}, author={Drew, C. Ashton and Eddy, Michele and Kwak, Thomas J. and Cope, W. Gregory and Augspurger, Tom}, year={2018}, month={Jun}, pages={343–356} }
 @article{grieshaber_penland_kwak_cope_heise_law_shea_aday_rice_kullman_et al._2018, title={Relation of contaminants to fish intersex in riverine sport fishes}, volume={643}, ISSN={0048-9697}, url={http://dx.doi.org/10.1016/J.SCITOTENV.2018.06.071}, DOI={10.1016/j.scitotenv.2018.06.071}, abstractNote={Endocrine active compounds (EACs) are pollutants that have been recognized as an emerging and widespread threat to aquatic ecosystems globally. Intersex, the presence of female germ cells within a predominantly male gonad, is considered a biomarker of endocrine disruption caused by EACs. We measured a suite of EACs and assessed their associated impacts on fish intersex occurrence and severity in a large, regulated river system in North Carolina and South Carolina, USA. Our specific objective was to determine the relationship of contaminants in water, sediment, and fish tissue with the occurrence and severity of the intersex condition in wild, adult black bass (Micropterus), sunfish (Lepomis), and catfish (Ictaluridae) species at 11 sites located on the Yadkin-Pee Dee River. Polycyclic aromatic hydrocarbons (PAHs), ethinylestradiol (EE2), and heavy metals were the most prevalent contaminants that exceeded effect levels for the protection of aquatic organisms. Fish intersex condition was most frequently observed and most severe in black basses and was less frequently detected and less severe in sunfishes and catfishes. The occurrence of the intersex condition in fish showed site-related effects, rather than increasing longitudinal trends from upstream to downstream. Mean black bass and catfish tissue contaminant concentrations were higher than that of sunfish, likely because of the latter's lower trophic position in the food web. Principal component analysis identified waterborne PAHs as the most correlated environmental contaminant with intersex occurrence and severity in black bass and sunfish. As indicated by the intersex condition, EACs have adverse but often variable effects on the health of wild sport fishes in this river, likely due to fluctuations in EAC inputs and the dynamic nature of the riverine system. These findings enhance the understanding of the relationship between contaminants and fish health and provide information to guide ecologically comprehensive conservation and management decisions.}, journal={Science of The Total Environment}, publisher={Elsevier BV}, author={Grieshaber, C.A. and Penland, T.N. and Kwak, T.J. and Cope, W.G. and Heise, R.J. and Law, J.M. and Shea, Damian and Aday, D.D. and Rice, J.A. and Kullman, S.W. and et al.}, year={2018}, month={Dec}, pages={73–89} }
 @article{johnson_leprevost_kwak_cope_2018, title={Selenium, Mercury, and Their Molar Ratio in Sportfish from Drinking Water Reservoirs}, volume={15}, ISSN={1660-4601}, url={http://dx.doi.org/10.3390/ijerph15091864}, DOI={10.3390/ijerph15091864}, abstractNote={Mercury (Hg) bioaccumulates in aquatic ecosystems and may pose a risk to humans who consume fish. Selenium (Se) has the ability to reduce Hg toxicity, but the current guidance for human consumption of fish is based on Hg concentration alone. The purpose of the present study was to examine the relationship between Se and Hg in freshwater sportfish, for which there is a paucity of existing data. We collected three species of fish from different trophic positions from two drinking water reservoirs in central North Carolina, USA, to assess Hg and Se concentrations in relation to fish total length and to compare two measures of the protective ability of Se, the Se:Hg molar ratio and Se health benefit value (HBVSe), to current guidance for Hg. According to the Se:Hg molar ratio, all of the low trophic position fish sampled and the middle trophic position fish sampled from one of the reservoirs were safe for consumption. The same number of fish were considered safe using the HBVSe. More fish were deemed unsafe when using the Se:Hg molar ratio and HBVSe than were considered unsafe when using the U.S. Environmental Protection Agency (USEPA) Hg threshold. These findings suggest that the measures of Se protection may be unnecessarily conservative or that the USEPA Hg threshold may not be sufficiently protective of human health, especially the health of sensitive populations like pregnant or nursing mothers and young children. Future examination of the Se:Hg molar ratio and HBVSe from a variety of fish tissue samples would help refine the accuracy of these measures so that they may be appropriately utilized in ecological and human health risk assessment.}, number={9}, journal={International Journal of Environmental Research and Public Health}, publisher={MDPI AG}, author={Johnson, Tara and LePrevost, Catherine and Kwak, Thomas and Cope, W.}, year={2018}, month={Aug}, pages={1864} }
 @article{collazo_terando_engman_fackler_kwak_2019, title={Toward a Resilience-Based Conservation Strategy for Wetlands in Puerto Rico: Meeting Challenges Posed by Environmental Change}, volume={39}, ISSN={["1943-6246"]}, url={https://doi.org/10.1007/s13157-018-1080-z}, DOI={10.1007/s13157-018-1080-z}, number={6}, journal={WETLANDS}, publisher={Springer Science and Business Media LLC}, author={Collazo, Jaime A. and Terando, Adam J. and Engman, Augustin C. and Fackler, Paul F. and Kwak, Thomas J.}, year={2019}, month={Dec}, pages={1255–1269} }
 @article{buczek_cope_mclaughlin_kwak_2017, title={ACUTE TOXICITY OF POLYACRYLAMIDE FLOCCULANTS TO EARLY LIFE STAGES OF FRESHWATER MUSSELS}, volume={36}, ISSN={["1552-8618"]}, DOI={10.1002/etc.3821}, abstractNote={AbstractPolyacrylamide has become an effective tool for reducing construction‐related suspended sediment and turbidity, which are considered to have significant adverse impacts on aquatic ecosystems and are a leading cause of the degradation of North American streams and rivers. However, little is known about the effects of polyacrylamide on many freshwater organisms, and prior to the present study, no information existed on the toxicity of polyacrylamide compounds to native freshwater mussels (family Unionidae), one of the most imperiled faunal groups globally. Following standard test guidelines, we exposed juvenile mussels (test duration 96 h) and glochidia larvae (test duration 24 h) to 5 different anionic polyacrylamide compounds and 1 non‐ionic compound. Species tested included the yellow lampmussel (Lampsilis cariosa), an Atlantic Slope species that is listed as endangered in North Carolina; the Appalachian elktoe (Alasmidonta raveneliana), a federally endangered Interior Basin species; and the washboard (Megalonaias nervosa), a common Interior Basin species. We found that median lethal concentrations (LC50s) of polyacrylamide ranged from 411.7 to >1000 mg/L for glochidia and from 126.8 to >1000 mg/L for juveniles. All LC50s were orders of magnitude greater (2–3) than concentrations typically recommended for turbidity control (1–5 mg/L), regardless of their molecular weight or charge density. The results demonstrate that the polyacrylamide compounds tested were not acutely toxic to the mussel species and life stages tested, indicating minimal risk of short‐term exposure from polyacrylamide applications in the environment. However, other potential uses of polyacrylamide in the environment (e.g., wastewater treatment, paper processing, mining, algae removal) and their chronic or sublethal effects remain uncertain and warrant additional investigation. Environ Toxicol Chem 2017;36:2715–2721. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.}, number={10}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, publisher={Wiley-Blackwell}, author={Buczek, Sean B. and Cope, W. Gregory and McLaughlin, Richard A. and Kwak, Thomas J.}, year={2017}, month={Oct}, pages={2715–2721} }
 @article{buttermore_cope_kwak_cooney_shea_lazaro_2018, title={Contaminants in tropical island streams and their biota}, volume={161}, ISSN={["1096-0953"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85038027709&partnerID=MN8TOARS}, DOI={10.1016/j.envres.2017.11.053}, abstractNote={Environmental contamination is problematic for tropical islands due to their typically dense human populations and competing land and water uses. The Caribbean island of Puerto Rico (USA) has a long history of anthropogenic chemical use, and its human population density is among the highest globally, providing a model environment to study contaminant impacts on tropical island stream ecosystems. Polycyclic Aromatic Hydrocarbons, historic-use chlorinated pesticides, current-use pesticides, Polychlorinated Biphenyls (PCBs), and metals (mercury, cadmium, copper, lead, nickel, zinc, and selenium) were quantified in the habitat and biota of Puerto Rico streams and assessed in relation to land-use patterns and toxicological thresholds. Water, sediment, and native fish and shrimp species were sampled in 13 rivers spanning broad watershed land-use characteristics during 2009–2010. Contrary to expectations, freshwater stream ecosystems in Puerto Rico were not severely polluted, likely due to frequent flushing flows and reduced deposition associated with recurring flood events. Notable exceptions of contamination were nickel in sediment within three agricultural watersheds (range 123–336 ppm dry weight) and organic contaminants (PCBs, organochlorine pesticides) and mercury in urban landscapes. At an urban site, PCBs in several fish species (Mountain Mullet Agonostomus monticola [range 0.019–0.030 ppm wet weight] and American Eel Anguilla rostrata [0.019–0.031 ppm wet weight]) may pose human health hazards, with concentrations exceeding the U.S. Environmental Protection Agency (EPA) consumption limit for 1 meal/month. American Eel at the urban site also contained dieldrin (range < detection-0.024 ppm wet weight) that exceeded the EPA maximum allowable consumption limit. The Bigmouth Sleeper Gobiomorous dormitor, an important piscivorus sport fish, accumulated low levels of organic contaminants in edible muscle tissue (due to its low lipid content) and may be most suitable for human consumption island-wide; only mercury at one site (an urban location) exceeded EPA's consumption limit of 3 meals/month for this species. These results comprise the first comprehensive island-wide contaminant assessment of Puerto Rico streams and biota and provide natural resource and public health agencies here and in similar tropical islands elsewhere with information needed to guide ecosystem and fisheries conservation and management and human health risk assessment.}, journal={ENVIRONMENTAL RESEARCH}, author={Buttermore, Elissa N. and Cope, W. Gregory and Kwak, Thomas J. and Cooney, Patrick B. and Shea, Damian and Lazaro, Peter R.}, year={2018}, month={Feb}, pages={615–623} }
 @article{myers_lynch_bunnell_chu_falke_kovach_krabbenhoft_kwak_paukert_2017, title={Global synthesis of the documented and projected effects of climate change on inland fishes}, volume={27}, ISSN={["1573-5184"]}, DOI={10.1007/s11160-017-9476-z}, number={2}, journal={REVIEWS IN FISH BIOLOGY AND FISHERIES}, author={Myers, Bonnie J. E. and Lynch, Abigail J. and Bunnell, David B. and Chu, Cindy and Falke, Jeffrey A. and Kovach, Ryan P. and Krabbenhoft, Trevor J. and Kwak, Thomas J. and Paukert, Craig P.}, year={2017}, month={Jun}, pages={339–361} }
 @article{engman_kwak_fischer_2017, title={Recruitment phenology and pelagic larval duration in Caribbean amphidromous fishes}, volume={36}, ISSN={["2161-9565"]}, DOI={10.1086/694176}, abstractNote={Amphidromous fishes are major components of oceanic tropical island stream ecosystems, such as those of the Caribbean island, Puerto Rico. Fishes with this life history face threats related to the requirement for connectivity between freshwater and marine environments during early life stages. Pelagic larval duration and recruitment phenology are 2 early life-history processes that are crucial for the biology, ecology, conservation, and management of amphidromous fishes. However, these processes are understudied in the Caribbean in general and have never been quantified in Puerto Rico. We quantified recruit abundance, recruitment phenology, and pelagic larval duration of several Caribbean amphidromous fish species in multiple rivers in Puerto Rico and explored the effects of environmental variables on recruit abundances. Two fish taxa—sirajo goby (Sicydium spp.) and River Goby (Awaous banana)—were exceptionally abundant as postlarvae and recruited to Caribbean rivers in pulsed migration episodes that were periodic at annual and lunar scales. Sirajo goby and River Goby recruit abundances varied among rivers, were greater at sunrise than at sunset, and were positively related to river discharge. The pelagic larval duration of 4 fish taxa ranged from a minimum of 28 d to a maximum of 103 d with means between 43 ± 7 d (SD) and 65 ± 11 d. We identified the last-quarter moon phase during the months of June through January as periods of maximum amphidromous fish recruitment to freshwater streams. The results and conclusions of our study can be applied to identify critical times to maintain river–ocean connectivity and stream flow for the benefit of the amphidromous fish population dynamics, stream ecology, and natural resources of the Caribbean.}, number={4}, journal={FRESHWATER SCIENCE}, author={Engman, Augustin C. and Kwak, Thomas J. and Fischer, Jesse R.}, year={2017}, month={Dec}, pages={851–865} }
 @article{lee pow_tilahun_creech_law_cope_kwak_rice_aday_kullman_2017, title={Windows of Susceptibility and Consequences of Early Life Exposures to 17β–estradiol on Medaka (Oryzias latipes) Reproductive Success}, volume={51}, ISSN={0013-936X 1520-5851}, url={http://dx.doi.org/10.1021/ACS.EST.7B01568}, DOI={10.1021/acs.est.7b01568}, abstractNote={Estrogens and estrogen mimics are commonly found in surface waters and are associated with deleterious effects in fish populations. Impaired fertility and fecundity in fish following chronic exposures to estrogens and estrogen mimics during critical windows in development are well documented. However, information regarding differential reproductive effects of exposure within defined developmental stages remains sparse. In this study, reproductive capacity was assessed in Japanese medaka (Oryzias latipes) after exposure to two concentrations of 17β-estradiol (E2β; 2 ng/L and 50 ng/L) during four distinct stages of development: gonad development, gonad differentiation, development of secondary sex characteristics (SSC) and gametogenesis. Exposure to E2β did not adversely impact survival, hatch success, growth, or genotypic ratios. In contrast, exposure to 50 ng/L E2β during SSC development altered phenotypic ratios and SSC. Exposure to both E2β treatments reduced reproductive capacity (fertility, fecundity) by 7.3-57.4% in adult medaka breeding pairs, with hindrance of SSC development resulting in the largest disruption in breeding capacity (51.6-57.4% decrease) in the high concentration. This study documents differential effects among four critical stages of development and provides insight into factors (window of exposure, exposure concentration and duration of exposure period) contributing to reproductive disruption in fish.}, number={9}, journal={Environmental Science & Technology}, publisher={American Chemical Society (ACS)}, author={Lee Pow, Crystal S.D. and Tilahun, Kedamawit and Creech, Kari and Law, J. Mac and Cope, W. Gregory and Kwak, Thomas J. and Rice, James A. and Aday, D. Derek and Kullman, Seth W.}, year={2017}, month={Apr}, pages={5296–5305} }
 @article{lynch_myers_chu_eby_falke_kovach_krabbenhoft_kwak_lyons_paukert_et al._2016, title={Climate Change Effects on North American Inland Fish Populations and Assemblages}, volume={41}, ISSN={["1548-8446"]}, DOI={10.1080/03632415.2016.1186016}, abstractNote={Climate is a critical driver of many fish populations, assemblages, and aquatic communities. However, direct observational studies of climate change impacts on North American inland fishes are rare. In this synthesis, we (1) summarize climate trends that may influence North American inland fish populations and assemblages, (2) compile 31 peer‐reviewed studies of documented climate change effects on North American inland fish populations and assemblages, and (3) highlight four case studies representing a variety of observed responses ranging from warmwater systems in the southwestern and southeastern United States to coldwater systems along the Pacific Coast and Canadian Shield. We conclude by identifying key data gaps and research needs to inform adaptive, ecosystem‐based approaches to managing North American inland fishes and fisheries in a changing climate.}, number={7}, journal={FISHERIES}, author={Lynch, Abigail J. and Myers, Bonnie J. E. and Chu, Cindy and Eby, Lisa A. and Falke, Jeffrey A. and Kovach, Ryan P. and Krabbenhoft, Trevor J. and Kwak, Thomas J. and Lyons, John and Paukert, Craig P. and et al.}, year={2016}, month={Jul}, pages={346–361} }
 @inproceedings{kwak_engman_fischer_lilyestrom_2016, title={Drivers of Caribbean freshwater ecosystems and fisheries}, booktitle={Freshwater, Fish and the Future: Proceedings of the Global Cross-Sectoral Conference}, author={Kwak, T. J. and Engman, A. C. and Fischer, J. R. and Lilyestrom, C. G.}, year={2016}, pages={219–232} }
 @article{favrot_kwak_2016, title={Efficiency of Two-Way Weirs and Prepositioned Electrofishing for Sampling Potamodromous Fish Migrations}, volume={36}, ISSN={["1548-8675"]}, DOI={10.1080/02755947.2015.1114537}, abstractNote={AbstractPotamodromy (i.e., migration entirely in freshwater) is a common life history strategy of North American lotic fishes, and efficient sampling methods for potamodromous fishes are needed to formulate conservation and management decisions. Many potamodromous fishes inhabit medium‐sized rivers and are mobile during spawning migrations, which complicates sampling with conventional gears (e.g., nets and electrofishing). We compared the efficiency of a passive migration technique (resistance board weirs) and an active technique (prepositioned areal electrofishers; [PAEs]) for sampling migrating potamodromous fishes in Valley River, a southern Appalachian Mountain river, from March through July 2006 and 2007. A total of 35 fish species from 10 families were collected, 32 species by PAE and 19 species by weir. Species richness and diversity were higher for PAE catch, and species dominance (i.e., proportion of assemblage composed of the three most abundant species) was higher for weir catch. Prepositioned areal electrofisher catch by number was considerably higher than weir catch, but biomass was lower for PAE catch. Weir catch decreased following the spawning migration, while PAEs continued to collect fish. Sampling bias associated with water velocity was detected for PAEs, but not weirs, and neither gear demonstrated depth bias in wadeable reaches. Mean fish mortality from PAEs was five times greater than that from weirs. Catch efficiency and composition comparisons indicated that weirs were effective at documenting migration chronology, sampling nocturnal migration, and yielding samples unbiased by water velocity or habitat, with low mortality. Prepositioned areal electrofishers are an appropriate sampling technique for seasonal fish occupancy objectives, while weirs are more suitable for quantitatively describing spawning migrations. Our comparative results may guide fisheries scientists in selecting an appropriate sampling gear and regime for research, monitoring, conservation, and management of potamodromous fishes.}, number={1}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Favrot, Scott D. and Kwak, Thomas J.}, year={2016}, pages={167–182} }
 @article{fisk_kwak_heise_2015, title={Effects of Regulated River Flows on Habitat Suitability for the Robust Redhorse}, volume={144}, ISSN={["1548-8659"]}, DOI={10.1080/00028487.2015.1042557}, abstractNote={AbstractThe Robust Redhorse Moxostoma robustum is a rare and imperiled fish, with wild populations occurring in three drainages from North Carolina to Georgia. Hydroelectric dams have altered the species' habitat and restricted its range. An augmented minimum‐flow regime that will affect Robust Redhorse habitat was recently prescribed for Blewett Falls Dam, a hydroelectric facility on the Pee Dee River, North Carolina. Our objective was to quantify suitable spawning and nonspawning habitat under current and proposed minimum‐flow regimes. We implanted radio transmitters into 27 adult Robust Redhorses and relocated the fish from spring 2008 to summer 2009, and we described habitat at 15 spawning capture locations. Nonspawning habitat consisted of deep, slow‐moving pools (mean depth = 2.3 m; mean velocity = 0.23 m/s), bedrock and sand substrates, and boulders or coarse woody debris as cover. Spawning habitat was characterized as shallower, faster‐moving water (mean depth = 0.84 m; mean velocity = 0.61 m/s) with gravel and cobble as substrates and boulders as cover associated with shoals. Telemetry relocations revealed two behavioral subgroups: a resident subgroup (linear range [mean ± SE] = 7.9 ± 3.7 river kilometers [rkm]) that remained near spawning areas in the Piedmont region throughout the year; and a migratory subgroup (linear range = 64.3 ± 8.4 rkm) that migrated extensively downstream into the Coastal Plain region. Spawning and nonspawning habitat suitability indices were developed based on field microhabitat measurements and were applied to model suitable available habitat (weighted usable area) for current and proposed augmented minimum flows. Suitable habitat (both spawning and nonspawning) increased for each proposed seasonal minimum flow relative to former minimum flows, with substantial increases for spawning sites. Our results contribute to an understanding of how regulated flows affect available habitats for imperiled species. Flow managers can use these findings to regulate discharge more effectively and to create and maintain important habitats during critical periods for priority species.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Fisk, J. Michael, II and Kwak, Thomas J. and Heise, Ryan J.}, year={2015}, pages={792–806} }
 @article{smith_kwak_2015, title={Tropical insular fish assemblages are resilient to flood disturbance}, volume={6}, ISSN={["2150-8925"]}, DOI={10.1890/es15-00224.1}, abstractNote={Periods of stable environmental conditions, favoring development of ecological communities regulated by density‐dependent processes, are interrupted by random periods of disturbance that may restructure communities. Disturbance may affect populations via habitat alteration, mortality, or displacement. We quantified fish habitat conditions, density, and movement before and after a major flood disturbance in a Caribbean island tropical river using habitat surveys, fish sampling and population estimates, radio telemetry, and passively monitored PIT tags. Native stream fish populations showed evidence of acute mortality and downstream displacement of surviving fish. All fish species were reduced in number at most life stages after the disturbance, but populations responded with recruitment and migration into vacated upstream habitats. Changes in density were uneven among size classes for most species, indicating altered size structures. Rapid recovery processes at the population level appeared to dampen effects at the assemblage level, as fish assemblage parameters (species richness and diversity) were unchanged by the flooding. The native fish assemblage appeared resilient to flood disturbance, rapidly compensating for mortality and displacement with increased recruitment and recolonization of upstream habitats.}, number={12}, journal={ECOSPHERE}, author={Smith, William E. and Kwak, Thomas J.}, year={2015}, month={Dec} }
 @article{smith_kwak_2014, title={A capture-recapture model of amphidromous fish dispersal}, volume={84}, ISSN={["1095-8649"]}, DOI={10.1111/jfb.12316}, abstractNote={Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio‐telemetry. Large numbers of fishes were tagged in Río Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2·5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack–Jolly–Seber model. A sub‐set of fishes were tagged with radio‐transmitters and tracked at weekly intervals to estimate fine‐scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Río Mameyes during two consecutive reproductive periods, thus demonstrating that both species follow an amphidromous, rather than catadromous, migratory strategy. Further, both species were relatively sedentary, with restricted linear ranges. While substantial dispersal of these species occurs at the larval stage during recruitment to fresh water, the results indicate minimal dispersal in spawning adults. Successful conservation of diadromous fauna on tropical islands requires management at both broad basin and localized spatial scales.}, number={4}, journal={JOURNAL OF FISH BIOLOGY}, author={Smith, W. E. and Kwak, T. J.}, year={2014}, month={Apr}, pages={897–912} }
 @article{archambault_cope_kwak_2014, title={Influence of sediment presence on freshwater mussel thermal tolerance}, volume={33}, ISSN={["2161-9565"]}, DOI={10.1086/674141}, abstractNote={Abstract: 
 Median lethal temperature (LT50) data from water-only exposures with the early life stages of freshwater mussels suggest that some species may be living near their upper thermal tolerances. However, evaluation of thermal sensitivity has never been conducted in sediment. Mussels live most of their lives burrowed in sediment, so understanding the effect of sediment on thermal sensitivity is a necessary step in evaluating the effectiveness of the water-only standard method, on which the regulatory framework for potential thermal criteria currently is based, as a test of thermal sensitivity. We developed a method for testing thermal sensitivity of juvenile mussels in sediment and used the method to assess thermal tolerance of 4 species across a range of temperatures common during summer. Stream beds may provide a thermal refuge in the wild, but we hypothesized that the presence of sediment alone does not alter thermal sensitivity. We also evaluated the effects of 2 temperature acclimation levels (22 and 27°C) and 2 water levels (watered and dewatered treatments). We then compared results from the sediment tests to those conducted using the water-only standard methods. We also conducted water-only LT tests with mussel larvae (glochidia) for comparison with the juvenile life stage. We found few consistent differences in thermal tolerance between sediment and water-only treatments, between acclimation temperatures, between waterlevel treatments, among species, or between juvenile and glochidial life stages (LT50 range = 33.3–37.2°C; mean = 35.6°C), supporting our hypothesis that the presence of sediment alone does not alter thermal sensitivity. The method we developed has potential for evaluating the role of other stressors (e.g., contaminants) in a more natural and complex environment.}, number={1}, journal={FRESHWATER SCIENCE}, author={Archambault, Jennifer M. and Cope, W. Gregory and Kwak, Thomas J.}, year={2014}, month={Mar}, pages={56–65} }
 @article{smith_kwak_2014, title={Otolith microchemistry of tropical diadromous fishes: spatial and migratory dynamics}, volume={84}, ISSN={["1095-8649"]}, DOI={10.1111/jfb.12317}, abstractNote={Otolith microchemistry was applied to quantify migratory variation and the proportion of native Caribbean stream fishes that undergo full or partial marine migration. Strontium and barium water chemistry in four Puerto Rico, U.S.A., rivers was clearly related to a salinity gradient; however, variation in water barium, and thus fish otoliths, was also dependent on river basin. Strontium was the most accurate index of longitudinal migration in tropical diadromous fish otoliths. Among the four species examined, bigmouth sleeper Gobiomorus dormitor, mountain mullet Agonostomus monticola, sirajo goby Sicydium spp. and river goby Awaous banana, most individuals were fully amphidromous, but 9–12% were semi‐amphidromous as recruits, having never experienced marine or estuarine conditions in early life stages and showing no evidence of marine elemental signatures in their otolith core. Populations of one species, G. dormitor, may have contained a small contingent of semi‐amphidromous adults, migratory individuals that periodically occupied marine or estuarine habitats (4%); however, adult migratory elemental signatures may have been confounded with those related to diet and physiology. These findings indicate the plasticity of migratory strategies of tropical diadromous fishes, which may be more variable than simple categorization might suggest.}, number={4}, journal={JOURNAL OF FISH BIOLOGY}, author={Smith, W. E. and Kwak, T. J.}, year={2014}, month={Apr}, pages={913–928} }
 @article{derolph_nelson_kwak_hain_2015, title={Predicting fine-scale distributions of peripheral aquatic species in headwater streams}, volume={5}, ISSN={["2045-7758"]}, DOI={10.1002/ece3.1331}, abstractNote={AbstractHeadwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.}, number={1}, journal={ECOLOGY AND EVOLUTION}, author={DeRolph, Christopher R. and Nelson, Stacy A. C. and Kwak, Thomas J. and Hain, Ernie F.}, year={2015}, month={Jan}, pages={152–163} }
 @article{weaver_kwak_pollock_2014, title={Sampling Characteristics and Calibration of Snorkel Counts to Estimate Stream Fish Populations}, volume={34}, ISSN={0275-5947 1548-8675}, url={http://dx.doi.org/10.1080/02755947.2014.951808}, DOI={10.1080/02755947.2014.951808}, abstractNote={AbstractSnorkeling is a versatile technique for estimating lotic fish population characteristics; however, few investigators have evaluated its accuracy at population or assemblage levels. We evaluated the accuracy of snorkeling using prepositioned areal electrofishing (PAE) for estimating fish populations in a medium‐sized Appalachian Mountain river during fall 2008 and summer 2009. Strip‐transect snorkel counts were calibrated with PAE counts in identical locations among macrohabitats, fish species or taxa, and seasons. Mean snorkeling efficiency (i.e., the proportion of individuals counted from the true population) among all taxa and seasons was 14.7% (SE, 2.5%), and the highest efficiencies were for River Chub Nocomis micropogon at 21.1% (SE, 5.9%), Central Stoneroller Campostoma anomalum at 20.3% (SE, 9.6%), and darters (Percidae) at 17.1% (SE, 3.7%), whereas efficiencies were lower for shiners (Notropis spp., Cyprinella spp., Luxilus spp.) at 8.2% (SE, 2.2%) and suckers (Catostomidae) at 6.6% (SE, 3.2%). Macrohabitat type, fish taxon, or sampling season did not significantly explain variance in snorkeling efficiency. Mean snorkeling detection probability (i.e., probability of detecting at least one individual of a taxon) among fish taxa and seasons was 58.4% (SE, 6.1%). We applied the efficiencies from our calibration study to adjust snorkel counts from an intensive snorkeling survey conducted in a nearby reach. Total fish density estimates from strip‐transect counts adjusted for snorkeling efficiency were 7,288 fish/ha (SE, 1,564) during summer and 15,805 fish/ha (SE, 4,947) during fall. Precision of fish density estimates is influenced by variation in snorkeling efficiency and sample size and may be increased with additional sampling effort. These results demonstrate the sampling properties and utility of snorkeling to characterize lotic fish assemblages with acceptable efficiency and detection probability, less effort, and no mortality, compared with traditional sampling methods.Received April 29, 2014; accepted July 23, 2014}, number={6}, journal={North American Journal of Fisheries Management}, publisher={Wiley}, author={Weaver, Daniel M. and Kwak, Thomas J. and Pollock, Kenneth H.}, year={2014}, month={Nov}, pages={1159–1166} }
 @article{sackett_pow_rubino_aday_cope_kullman_rice_kwak_law_2015, title={Sources of endocrine-disrupting compounds in North Carolina waterways: A geographic information systems approach}, volume={34}, ISSN={0730-7268}, url={http://dx.doi.org/10.1002/ETC.2797}, DOI={10.1002/etc.2797}, abstractNote={AbstractThe presence of endocrine‐disrupting compounds (EDCs), particularly estrogenic compounds, in the environment has drawn public attention across the globe, yet a clear understanding of the extent and distribution of estrogenic EDCs in surface waters and their relationship to potential sources is lacking. The objective of the present study was to identify and examine the potential input of estrogenic EDC sources in North Carolina water bodies using a geographic information system (GIS) mapping and analysis approach. Existing data from state and federal agencies were used to create point and nonpoint source maps depicting the cumulative contribution of potential sources of estrogenic EDCs to North Carolina surface waters. Water was collected from 33 sites (12 associated with potential point sources, 12 associated with potential nonpoint sources, and 9 reference), to validate the predictive results of the GIS analysis. Estrogenicity (measured as 17β‐estradiol equivalence) ranged from 0.06 ng/L to 56.9 ng/L. However, the majority of sites (88%) had water 17β‐estradiol concentrations below 1 ng/L. Sites associated with point and nonpoint sources had significantly higher 17β‐estradiol levels than reference sites. The results suggested that water 17β‐estradiol was reflective of GIS predictions, confirming the relevance of landscape‐level influences on water quality and validating the GIS approach to characterize such relationships. Environ Toxicol Chem 2014;9999:1–9. © 2014 SETAC}, number={2}, journal={Environmental Toxicology and Chemistry}, publisher={Wiley}, author={Sackett, Dana K. and Pow, Crystal Lee and Rubino, Matthew J. and Aday, D. Derek and Cope, W. Gregory and Kullman, Seth and Rice, James A. and Kwak, Thomas J. and Law, Mac}, year={2015}, month={Jan}, pages={437–445} }
 @article{weaver_kwak_2013, title={Assessing Effects of Stocked Trout on Nongame Fish Assemblages in Southern Appalachian Mountain Streams}, volume={142}, ISSN={["1548-8659"]}, DOI={10.1080/00028487.2013.815662}, abstractNote={AbstractFisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before–after, control–impact (BACI) experimental design to detect short‐term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long‐term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery‐reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream management, and conservation of native fishes.}, number={6}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Weaver, Daniel M. and Kwak, Thomas J.}, year={2013}, month={Nov}, pages={1495–1507} }
 @article{archambault_cope_kwak_2013, title={Burrowing, byssus, and biomarkers: behavioral and physiological indicators of sublethal thermal stress in freshwater mussels (Unionidae)}, volume={46}, ISSN={["1029-0362"]}, DOI={10.1080/10236244.2013.805891}, abstractNote={Recent research has elucidated the acute lethal effects of elevated water temperatures to glochidia (larvae), juvenile, and adult life stages of freshwater mussels (Order Unionida), but few studies have focused on sublethal effects of thermal stress. We evaluated the sublethal effects of elevated temperature on burrowing behavior and byssus production in juveniles, and on enzymatic biomarkers of stress in adults in acute (96 h) laboratory experiments in sediment, with two acclimation temperatures (22 and 27 °C) and two experimental water levels (watered and dewatered) as proxies for flow regime. Increasing temperature significantly reduced burrowing in all five species tested, and the dewatered treatment (a proxy for drought conditions) reduced burrowing in all but Amblema plicata. Production of byssal threads was affected most drastically by flow regime, with the probability of byssus presence reduced by 93–99% in the dewatered treatment, compared to the watered treatment (a proxy for low flow conditions); increasing temperature alone reduced byssus by 18–35%. Alanine aminotransferase and aspartate aminotransferase were significantly affected by treatment temperature in the 27 °C acclimation, watered test (p = 0.04 and 0.02, respectively). Our results are important in the context of climate change, because stream temperature and flow are expected to change with increasing air temperature and altered precipitation patterns.}, number={4}, journal={MARINE AND FRESHWATER BEHAVIOUR AND PHYSIOLOGY}, author={Archambault, Jennifer M. and Cope, W. Gregory and Kwak, Thomas J.}, year={2013}, month={Jul}, pages={229–250} }
 @article{fisk_kwak_heise_2014, title={Modelling riverine habitat for robust redhorse: assessment for reintroduction of an imperilled species}, volume={21}, ISSN={["1365-2400"]}, DOI={10.1111/fme.12050}, abstractNote={AbstractA critical component of a species reintroduction is assessment of contemporary habitat suitability. The robust redhorse, Moxostoma robustum (Cope), is an imperilled catostomid that occupies a restricted range in the south‐eastern USA. A remnant population persists downstream of Blewett Falls Dam, the terminal dam in the Pee Dee River, North Carolina. Reintroduction upstream of Blewett Falls Dam may promote long‐term survival of this population. Tillery Dam is the next hydroelectric facility upstream, which includes a 30 rkm lotic reach. Habitat suitability indices developed in the Pee Dee River were applied to model suitable habitat for proposed minimum flows downstream of Tillery Dam. Modelling results indicate that the Tillery reach provides suitable robust redhorse habitat, with spawning habitat more abundant than non‐spawning habitat. Sensitivity analyses suggested that suitable water depth and substrate were limiting physical habitat variables. These results can inform decisions on flow regulation and guide planning for reintroduction of the robust redhorse and other species.}, number={1}, journal={FISHERIES MANAGEMENT AND ECOLOGY}, author={Fisk, J. M., II and Kwak, T. J. and Heise, R. J.}, year={2014}, month={Feb}, pages={57–67} }
 @article{cooney_kwak_2013, title={Spatial Extent and Dynamics of Dam Impacts on Tropical Island Freshwater Fish Assemblages}, volume={63}, ISSN={["1525-3244"]}, DOI={10.1525/bio.2013.63.3.6}, abstractNote={Habitat connectivity is vital to the persistence of migratory fishes. Native tropical island stream fish assemblages composed of diadromous species require intact corridors between ocean and riverine habitats. High dams block fish migration, but low-head artificial barriers are more widespread and are rarely assessed for impacts. Among all 46 drainages in Puerto Rico, we identified and surveyed 335 artificial barriers that hinder fish migration to 74.5% of the upstream habitat. We also surveyed occupancy of native diadromous fishes (Anguillidae, Eleotridae, Gobiidae, and Mugilidae) in 118 river reaches. Occupancy models demonstrated that barriers 2 meters (m) high restricted nongoby fish migration and extirpated those fish upstream of 4-m barriers. Gobies are adapted to climbing and are restricted by 12-m barriers and extirpated upstream of 32-m barriers. Our findings quantitatively illustrate the extensive impact of low-head structures on island stream fauna and provide guidance for natural resource management, habitat restoration, and water development strategies.}, number={3}, journal={BIOSCIENCE}, author={Cooney, Patrick B. and Kwak, Thomas J.}, year={2013}, month={Mar}, pages={176–190} }
 @article{archambault_cope_kwak_2014, title={Survival and behaviour of juvenile unionid mussels exposed to thermal stress and dewatering in the presence of a sediment temperature gradient}, volume={59}, ISSN={["1365-2427"]}, DOI={10.1111/fwb.12290}, abstractNote={Summary


Freshwater mussels (Unionidae) are a highly imperilled faunal group. One critical threat is thermal sensitivity, because global climate change and other anthropogenic activities contribute to increasing stream temperature and altered hydrologic flow that may be detrimental to freshwater mussels.

We incorporated four benthic environmental components – temperature, sediment, water level (a surrogate for flow) and a vertical thermal gradient in the sediment column – in laboratory mesocosm experiments with juveniles of two species of freshwater mussels (Lampsilis abrupta and Lampsilis radiata) and tested their effects on survival, burrowing behaviour and byssus production.

Increasing temperature diminished burrowing behaviour significantly in both species (P < 0.01), and the dewatered treatment significantly reduced burrowing in L. radiata, compared with that in the watered treatment. Increasing temperature also significantly reduced byssus production in both species (P < 0.01). Median lethal temperatures (LT50) ranged from 29.9 to 35.6 °C. Mussels did not burrow beneath the top stratum of sediment (0–2.5 cm) and thus did not use the available thermal refuge.

Our findings suggest that rising stream water temperature and dewatering may directly impact freshwater mussel abundance by causing mortality and may have indirect impacts via sublethal effects. Reduced burrowing capacity may hamper ability to escape predation or unfavourably high or low flows, and decreased byssus production may inhibit attachment and dispersal capabilities in juveniles.

}, number={3}, journal={FRESHWATER BIOLOGY}, author={Archambault, Jennifer M. and Cope, W. Gregory and Kwak, Thomas J.}, year={2014}, month={Mar}, pages={601–613} }
 @article{fisk_kwak_heise_sessions_2013, title={REDD DEWATERING EFFECTS ON HATCHING AND LARVAL SURVIVAL OF THE ROBUST REDHORSE}, volume={29}, ISSN={["1535-1467"]}, DOI={10.1002/rra.2561}, abstractNote={ABSTRACTRiverine habitats have been altered and fragmented from hydroelectric dams and change spatially and temporally with hydropower flow releases. Hydropeaking flow regimes for electrical power production inundate areas that create temporary suitable habitat for fish that may be rapidly drained. Robust redhorse Moxostoma robustum, an imperiled, rare fish species, uses such temporary habitats to spawn, but when power generation ceases, these areas are dewatered until the next pulse of water is released. We experimentally simulated the effects of dewatering periods on the survival of robust redhorse eggs and larvae in the laboratory. Robust redhorse eggs were placed in gravel in eyeing‐hatching jars (three jars per treatment) and subjected to one of four dewatering periods (6, 12, 24 and 48 h), followed by 12 h of inundation for each treatment, and a control treatment was never dewatered. Egg desiccation was observed in some eggs in the 24‐ and 48‐h treatments after one dewatering period. For all treatments except the control, the subsequent dewatering period after eggs hatched was lethal. Larval emergence for the control treatment was observed on day 5 post‐hatching and continued until the end of the experiment (day 21). Larval survival was significantly different between the control and all dewatering treatments for individuals in the gravel. These findings support the need for hydropower facilities to set minimum flows to maintain inundation of spawning areas for robust redhorse and other species to reduce dewatering mortality. Copyright © 2012 John Wiley & Sons, Ltd.}, number={5}, journal={RIVER RESEARCH AND APPLICATIONS}, author={Fisk, J. M., II and Kwak, T. J. and Heise, R. J. and Sessions, F. W.}, year={2013}, month={Jun}, pages={574–581} }
 @article{quinn_kwak_2011, title={Movement and Survival of Brown Trout and Rainbow Trout in an Ozark Tailwater River}, volume={31}, ISSN={["0275-5947"]}, DOI={10.1080/02755947.2011.576204}, abstractNote={AbstractWe evaluated the movement of adult brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss in relation to a catch‐and‐release area in the White River downstream from Beaver Dam, Arkansas. Nine fish of each species were implanted with radio transmitters and monitored from July 1996 to July 1997. The 1.5‐km river length of a catch‐and‐release area (closed to angler harvest) was greater than the total linear range of 72% of the trout (13 of 18 fish), but it did not include two brown trout spawning riffles, suggesting that it effectively protects resident fish within the catch‐and‐release area except during spawning. The total detected linear range of movement varied from 172 to 3,559 m for brown trout and from 205 to 3,023 m for rainbow trout. The movements of both species appeared to be generally similar to that in unregulated river systems. The annual apparent survival of both trout species was less than 0.40, and exploitation was 44%. Management to protect fish on spawning riffles may be considered if management for wild brown trout becomes a priority.Received August 31, 2010; accepted January 20, 2011}, number={2}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Quinn, Jeffrey W. and Kwak, Thomas J.}, year={2011}, pages={299–304} }
 @article{baumann_kwak_2011, title={Trophic Relations of Introduced Flathead Catfish in an Atlantic River}, volume={140}, ISSN={["1548-8659"]}, DOI={10.1080/00028487.2011.607046}, abstractNote={AbstractThe flathead catfish Pylodictis olivaris is a large piscivore that is native to the Mississippi and Rio Grande river drainages but that has been widely introduced across the United States. River ecologists and fisheries managers are concerned about introduced flathead catfish populations because of the negative impacts on native fish communities or imperiled species associated with direct predation and indirect competition from this apex predator. We studied the trophic relations of introduced flathead catfish in an Atlantic river to further understand the effects on native fish communities. Crayfish (Astacidea) occurred most frequently in the flathead catfish diet, while sunfish Lepomis spp. comprised the greatest percentage by weight. Neither of two sympatric imperiled fish species (the federally endangered Cape Fear shiner Notropis mekistocholas and the Carolina redhorse Moxostoma sp., a federal species of concern) was found in any diet sample. An ontogenetic shift in diet was evident when flathead catfish reached about 300 mm, and length significantly explained the variation in the percent composition by weight of sunfish and darters Etheostoma and Percina spp. Flathead catfish showed positive prey selectivity for taxa that occupied similar benthic microhabitat, highlighting the importance of opportunistic feeding and prey encounter rates. Flathead catfish displayed a highly variable diel feeding chronology during July, when they had a mean stomach fullness of 0.32%, but then showed a single midday feeding peak during August (mean fullness = 0.52%). The gastric evacuation rate increased between July (0.40/h) and August (0.59/h), as did daily ration, which more than doubled between the 2 months (3.06% versus 7.37%). Our findings increase the understanding of introduced flathead catfish trophic relations and the degree of vulnerability among prey taxa, which resource managers may consider in fisheries management and conservation of native fish populations and imperiled species.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Baumann, Jessica R. and Kwak, Thomas J.}, year={2011}, month={Jul}, pages={1120–1134} }
 @article{cope_holliman_kwak_oakley_lazaro_shea_augspurger_law_henne_ware_et al._2011, title={Assessing water quality suitability for shortnose sturgeon in the Roanoke River, North Carolina, USA with an in situ bioassay approach}, volume={27}, ISSN={["0175-8659"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78751690460&partnerID=MN8TOARS}, DOI={10.1111/j.1439-0426.2010.01570.x}, abstractNote={Summary 
 
The aim of this study was to determine the suitability of water quality in the Roanoke River of North Carolina for supporting shortnose sturgeon Acipenser brevirostrum, an endangered species in the United States. Fathead minnows Pimephales promelas were also evaluated alongside the sturgeon as a comparative species to measure potential differences in fish survival, growth, contaminant accumulation, and histopathology in a 28-day in situ toxicity test. Captively propagated juvenile shortnose sturgeon (total length 49 ± 8 mm, mean ± SD) and fathead minnows (total length 39 ± 3 mm, mean ± SD) were used in the test and their outcomes were compared to simultaneous measurements of water quality (temperature, dissolved oxygen, pH, conductivity, total ammonia nitrogen, hardness, alkalinity, turbidity) and contaminant chemistry (metals, polycyclic aromatic hydrocarbons, organochlorine pesticides, current use pesticides, polychlorinated biphenyls) in river water and sediment. In the in situ test, there were three non-riverine control sites and eight riverine test sites with three replicate cages (25 × 15-cm (OD) clear plexiglass with 200-μm tear-resistant Nitex® screen over each end) of 20 shortnose sturgeon per cage at each site. There was a single cage of fathead minnows also deployed at each site alongside the sturgeon cages. Survival of caged shortnose sturgeon among the riverine sites averaged 9% (range 1.7–25%) on day 22 of the 28-day study, whereas sturgeon survival at the non-riverine control sites averaged 64% (range 33–98%). In contrast to sturgeon, only one riverine deployed fathead minnow died (average 99.4% survival) over the 28-day test period and none of the control fathead minnows died. Although chemical analyses revealed the presence of retene (7-isopropyl-1-methylphenanthrene), a pulp and paper mill derived compound with known dioxin-like toxicity to early life stages of fish, in significant quantities in the water (251–603 ng L−1) and sediment (up to 5000 ng g−1 dry weight) at several river sites, no correlation was detected of adverse water quality conditions or measured contaminant concentrations to the poor survival of sturgeon among riverine test sites. Histopathology analysis determined that the mortality of the river deployed shortnose sturgeon was likely due to liver and kidney lesions from an unknown agent(s). Given the poor survival of shortnose sturgeon (9%) and high survival of fathead minnows (99.4%) at the riverine test sites, our study indicates that conditions in the Roanoke River are incongruous with the needs of juvenile shortnose sturgeon and that fathead minnows, commonly used standard toxicity test organisms, do not adequately predict the sensitivity of shortnose sturgeon. Therefore, additional research is needed to help identify specific limiting factors and management actions for the enhancement and recovery of this imperiled fish species.}, number={1}, journal={JOURNAL OF APPLIED ICHTHYOLOGY}, author={Cope, W.G. and Holliman, F.M. and Kwak, T.J. and Oakley, N.C. and Lazaro, P.R. and Shea, Damian and Augspurger, T. and Law, J.M. and Henne, J.P. and Ware, K.M. and et al.}, year={2011}, month={Feb}, pages={1–12} }
 @article{midway_aday_kwak_gross_2010, title={Cover Preference of the Carolina Madtom (Noturus furiosus), an Imperiled, Endemic Southeastern Stream Fish}, volume={25}, ISSN={0270-5060 2156-6941}, url={http://dx.doi.org/10.1080/02705060.2010.9664368}, DOI={10.1080/02705060.2010.9664368}, abstractNote={ABSTRACT In a laboratory setting, we investigated cover preference of the Carolina madtom (Noturus furiosus), an imperiled, endemic southeastern USA stream fish. Fish were tested individually and given 24 hours to make a selection from four cover options, including rock, leaf pack, mussel shell, and an artificial cover unit. Among 30 trials, Carolina madtom preferred the artificial cover unit, selecting it 63% of the time. Rock was selected 23% of the time, and leaf pack 13%. Mussel shells were not selected during any trial.}, number={1}, journal={Journal of Freshwater Ecology}, publisher={Informa UK Limited}, author={Midway, S. R. and Aday, D. D. and Kwak, T. J. and Gross, K.}, year={2010}, month={Mar}, pages={151–154} }
 @article{cooney_kwak_2010, title={Development of Standard Weight Equations for Caribbean and Gulf of Mexico Amphidromous Fishes}, volume={30}, ISSN={["1548-8675"]}, DOI={10.1577/m10-058.1}, abstractNote={AbstractWe collected and compiled length and weight information from four countries and one commonwealth to develop standard weight (Ws) equations for three amphidromous fish species native to the Caribbean and Gulf of Mexico regions: mountain mullet Agonostomus monticola (N = 9,768 individuals, 52 populations), river goby Awaous banana (N = 1,847 individuals, 62 populations), and bigmouth sleeper Gobiomorus dormitor (N = 2,983 individuals, 53 populations). Linear and quadratic Ws equations for three quartiles (25%, median, 75%) are presented for these three species. The length–weight relationship from eight lentic bigmouth sleeper populations was significantly different from that of lotic populations, reflecting higher weights of juvenile fish (<70 mm total length) in lentic environments. Thus, independent Ws equations were developed for lotic populations of bigmouth sleepers. Ws equations were not developed from lentic bigmouth sleeper populations alone due to the low number of applicable populations caused by life history constraints; the equation from combined lentic and lotic populations is suggested for application to lentic bigmouth sleeper populations. These morphometric relationships for amphidromous fishes may improve the ability to assess existing and potential sport fisheries and allow ecological assessment based on fish condition.}, number={5}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Cooney, Patrick B. and Kwak, Thomas J.}, year={2010}, month={Oct}, pages={1203–1209} }
 @article{mosher_cope_weber_shea_kwak_2012, title={Effects of lead on Na+, K+-ATPase and hemolymph ion concentrations in the freshwater mussel Elliptio complanata}, volume={27}, ISSN={1520-4081}, url={http://dx.doi.org/10.1002/tox.20639}, DOI={10.1002/tox.20639}, abstractNote={AbstractFreshwater mussels are an imperiled fauna exposed to a variety of environmental toxicants such as lead (Pb) and studies are urgently needed to assess their health and condition to guide conservation efforts. A 28‐day laboratory toxicity test with Pb and adult Eastern elliptio mussels (Elliptio complanata) was conducted to determine uptake kinetics and to assess the toxicological effects of Pb exposure. Test mussels were collected from a relatively uncontaminated reference site and exposed to a water‐only control and five concentrations of Pb (as lead nitrate) ranging from 1 to 245 μg/L in a static renewal test with a water hardness of 42 mg/L. Endpoints included tissue Pb concentrations, hemolymph Pb and ion (Na+, K+, Cl−, Ca2+) concentrations, and Na+, K+‐ATPase enzyme activity in gill tissue. Mussels accumulated Pb rapidly, with tissue concentrations increasing at an exposure‐dependent rate for the first 2 weeks, but with no significant increase from 2 to 4 weeks. Mussel tissue Pb concentrations ranged from 0.34 to 898 μg/g dry weight, were strongly related to Pb in test water at every time interval (7, 14, 21, and 28 days), and did not significantly increase after day 14. Hemolymph Pb concentration was variable, dependent on exposure concentration, and showed no appreciable change with time beyond day 7, except for mussels in the greatest exposure concentration (245 μg/L), which showed a significant reduction in Pb by 28 days, suggesting a threshold for Pb binding or elimination in hemolymph at concentrations near 1000 μg/g. The Na+, K+‐ATPase activity in the gill tissue of mussels was significantly reduced by Pb on day 28 and was highly correlated with tissue Pb concentration (R2 = 0.92; P = 0.013). The Na+, K+‐ATPase activity was correlated with reduced hemolymph Na+ concentration at the greatest Pb exposure when enzyme activity was at 30% of controls. Hemolymph Ca2+ concentration increased significantly in mussels from the greatest Pb exposure and may be due to remobilization from the shell in an attempt to buffer the hemolymph against Pb uptake and toxicity. We conclude that Na+, K+‐ATPase activity in mussels was adversely affected by Pb exposure, however, because the effects on activity were variable at the lower test concentrations, additional research is warranted over this range of exposures. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.}, number={5}, journal={Environmental Toxicology}, publisher={Wiley}, author={Mosher, Shad and Cope, W. Gregory and Weber, Frank X. and Shea, Damian and Kwak, Thomas J.}, year={2012}, month={May}, pages={268–276} }
 @article{midway_kwak_aday_2010, title={Habitat Suitability of the Carolina Madtom, an Imperiled, Endemic Stream Fish}, volume={139}, ISSN={["1548-8659"]}, DOI={10.1577/t08-238.1}, abstractNote={AbstractThe Carolina madtom Noturus furiosus is an imperiled stream ictalurid that is endemic to the Tar and Neuse River basins in North Carolina. The Carolina madtom is listed as a threatened species by the state of North Carolina, and whereas recent distribution surveys have found that the Tar River basin population occupies a range similar to its historical range, the Neuse River basin population has shown recent significant decline. Quantification of habitat requirements and availability is critical for effective management and subsequent survival of the species. We investigated six reaches (three in each basin) to (1) quantify Carolina madtom microhabitat use, availability, and suitability; (2) compare suitable microhabitat availability between the two basins; and (3) examine use of an instream artificial cover unit. Carolina madtoms were located and their habitat was quantified at four of the six survey reaches. They most frequently occupied shallow to moderate depths of swift moving water over a sand substrate and used cobble for cover. Univariate and principal components analyses both showed that Carolina madtom use of instream habitat was selective (i.e., nonrandom). Interbasin comparisons suggested that suitable microhabitats were more prevalent in the impacted Neuse River basin than in the Tar River basin. We suggest that other physical or biotic effects may be responsible for the decline in the Neuse River basin population. We designed instream artificial cover units that were occupied by Carolina madtoms (25% of the time) and occasionally by other organisms. Carolina madtom abundance among all areas treated with the artificial cover unit was statistically higher than that in the control areas, demonstrating use of artificial cover when available. Microhabitat characteristics of occupied artificial cover units closely resembled those of natural instream microhabitat used by Carolina madtoms; these units present an option for conservation and restoration if increased management is deemed necessary. Results from our study provide habitat suitability criteria and artificial cover information that can inform management and conservation of the Carolina madtom.}, number={2}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Midway, Stephen R. and Kwak, Thomas J. and Aday, D. Derek}, year={2010}, month={Mar}, pages={325–338} }
 @article{craven_peterson_freeman_kwak_irwin_2010, title={Modeling the Relations Between Flow Regime Components, Species Traits, and Spawning Success of Fishes in Warmwater Streams}, volume={46}, ISSN={["1432-1009"]}, DOI={10.1007/s00267-010-9511-5}, abstractNote={Modifications to stream hydrologic regimes can have a profound influence on the dynamics of their fish populations. Using hierarchical linear models, we examined the relations between flow regime and young-of-year fish density using fish sampling and discharge data from three different warmwater streams in Illinois, Alabama, and Georgia. We used an information theoretic approach to evaluate the relative support for models describing hypothesized influences of five flow regime components representing: short-term high and low flows; short-term flow stability; and long-term mean flows and flow stability on fish reproductive success during fish spawning and rearing periods. We also evaluated the influence of ten fish species traits on fish reproductive success. Species traits included spawning duration, reproductive strategy, egg incubation rate, swimming locomotion morphology, general habitat preference, and food habits. Model selection results indicated that young-of-year fish density was positively related to short-term high flows during the spawning period and negatively related to flow variability during the rearing period. However, the effect of the flow regime components varied substantially among species, but was related to species traits. The effect of short-term high flows on the reproductive success was lower for species that broadcast their eggs during spawning. Species with cruiser swimming locomotion morphologies (e.g., Micropterus) also were more vulnerable to variable flows during the rearing period. Our models provide insight into the conditions and timing of flows that influence the reproductive success of warmwater stream fishes and may guide decisions related to stream regulation and management.}, number={2}, journal={ENVIRONMENTAL MANAGEMENT}, author={Craven, Scott W. and Peterson, James T. and Freeman, Mary C. and Kwak, Thomas J. and Irwin, Elise}, year={2010}, month={Aug}, pages={181–194} }
 @article{neal_lilyestrom_kwak_2009, title={Factors Influencing Tropical Island Freshwater Fishes: Species, Status, and Management Implications in Puerto Rico}, volume={34}, ISSN={["1548-8446"]}, DOI={10.1577/1548-8446-34.11.546}, abstractNote={AbstractAnthropogenic effects including river regulation, watershed development, contamination, and fish introductions have substantially affected the majority of freshwater habitats in Europe and North America. This pattern of resource development and degradation is widespread in the tropics, and often little is known about the resources before they are lost. This article describes the freshwater resources of Puerto Rico and identifies factors that threaten conservation of native fishes. The fishes found in freshwater habitats of Puerto Rico represent a moderately diverse assemblage composed of 14 orders, 29 families, and 82 species. There are fewer than 10 species of native peripherally‐freshwater fish that require a link to marine systems. Introductions of nonindigenous species have greatly expanded fish diversity in freshwater systems, and native estuarine and marine species (18 families) also commonly enter lowland rivers and brackish lagoons. Environmental alterations, including land use and development, stream channelization, pollution, and the impoundment of rivers, combined with nonnative species introductions threaten the health and sustainability of aquatic resources in Puerto Rico. Six principal areas for attention that are important influences on the current and future status of the freshwater fish resources of Puerto Rico are identified and discussed.}, number={11}, journal={FISHERIES}, author={Neal, J. Wesley and Lilyestrom, Craig G. and Kwak, Thomas J.}, year={2009}, month={Nov}, pages={546–554} }
 @article{berkson_hunt_whitehead_murie_kwak_boreman_2009, title={Is There a Shortage of Fisheries Stock Assessment Scientists?}, volume={34}, ISSN={["1548-8446"]}, DOI={10.1577/1548-8446-34.5.217}, abstractNote={FisheriesVolume 34, Issue 5 p. 217-219 Essay: Education Is There a Shortage of Fisheries Stock Assessment Scientists? J. Berkson, J. Berkson Jim.Berkson@NOAA.gov Search for more papers by this authorK. M. Hunt, K. M. HuntSearch for more papers by this authorJ. C. Whitehead, J. C. WhiteheadSearch for more papers by this authorD. J. Murie, D. J. MurieSearch for more papers by this authorT. J. Kwak, T. J. KwakSearch for more papers by this authorJ. Boreman, J. BoremanSearch for more papers by this author J. Berkson, J. Berkson Jim.Berkson@NOAA.gov Search for more papers by this authorK. M. Hunt, K. M. HuntSearch for more papers by this authorJ. C. Whitehead, J. C. WhiteheadSearch for more papers by this authorD. J. Murie, D. J. MurieSearch for more papers by this authorT. J. Kwak, T. J. KwakSearch for more papers by this authorJ. Boreman, J. BoremanSearch for more papers by this author First published: 09 January 2011 https://doi.org/10.1577/1548-8446-34.5.217Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume34, Issue5May 2009Pages 217-219 RelatedInformation}, number={5}, journal={FISHERIES}, author={Berkson, J. and Hunt, K. M. and Whitehead, J. C. and Murie, D. J. and Kwak, T. J. and Boreman, J.}, year={2009}, month={May}, pages={217–219} }
 @article{hewitt_kwak_cope_pollock_2009, title={Population Density and Instream Habitat Suitability of the Endangered Cape Fear Shiner}, volume={138}, ISSN={["1548-8659"]}, DOI={10.1577/t08-038.1}, abstractNote={AbstractThe Cape Fear shinerNotropis mekistocholasis an endangered minnow endemic to the Cape Fear River basin of North Carolina; only five populations remain, all of which are declining. Determining the population densities and habitat requirements of the species is critical to its survival and restoration planning. We conducted population surveys (four sites) and instream microhabitat suitability analyses (six sites) on the Rocky and Deep rivers to (1) estimate the population density of Cape Fear shiners, (2) quantify the use, availability, and suitability of microhabitats, and (3) determine whether physical habitat alterations were a likely cause of local extirpations and whether instream habitat limits the occurrence and density of this species. Density ranged from 795 fish/ha to 1,393 fish/ha (4,768–7,392 fish/km) at three of the sites surveyed and was too low to be estimated at the fourth site. The fish most frequently occupied riffles and velocity breaks at moderate depths over gravel substrates. It occupied microhabitats nonrandomly with respect to availability; the microhabitats occupied were similar between spawning and postspawning seasons but shallower during spawning. Comparisons of suitable habitat among sites where the fish is extant, rare, or extirpated suggest that suitable substrate (gravel) is lacking where the fish is rare and that suitable microhabitat combinations, especially with respect to water velocity, are rare at all sites. Potential reintroduction sites where the species is rare or extirpated were shallower than extant sites, and one site where the fish is extirpated contained suitable physical habitat but lacked adequate water quality. Another site where the species is rare would require substrate alteration to improve conditions. The survival and recovery of the Cape Fear shiner is dependent on the protection of remaining suitable physical habitat with approaches that consider instream habitat, water quality, and biotic interactions as well as human uses and alterations of the river, riparian zone, and watershed.}, number={6}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Hewitt, Amanda H. and Kwak, Thomas J. and Cope, W. Gregory and Pollock, Kenneth H.}, year={2009}, month={Nov}, pages={1439–1457} }
 @article{holliman_davis_bogan_kwak_cope_levine_2008, title={Magnetic resonance imaging of live freshwater mussels (Unionidae)}, volume={127}, ISSN={["1744-7410"]}, DOI={10.1111/j.1744-7410.2008.00143.x}, abstractNote={Abstract.  We examined the soft tissues of live freshwater mussels, Eastern elliptio Elliptio complanata, via magnetic resonance imaging (MRI), acquiring data with a widely available human whole‐body MRI system. Anatomical features depicted in the profile images included the foot, stomach, intestine, anterior and posterior adductor muscles, and pericardial cavity. Noteworthy observations on soft tissue morphology included a concentration of lipids at the most posterior aspect of the foot, the presence of hemolymph‐filled fissures in the posterior adductor muscle, the presence of a relatively large hemolymph‐filled sinus adjacent to the posterior adductor muscle (at the ventral‐anterior aspect), and segmentation of the intestine (a diagnostic description not reported previously in Unionidae). Relatively little is known about the basic biology and ecological physiology of freshwater mussels. Traditional approaches for studying anatomy and tissue processes, and for measuring sub‐lethal physiological stress, are destructive or invasive. Our study, the first to evaluate freshwater mussel soft tissues by MRI, clarifies the body plan of unionid mussels and demonstrates the efficacy of this technology for in vivo evaluation of the structure, function, and integrity of mussel soft tissues.}, number={4}, journal={INVERTEBRATE BIOLOGY}, author={Holliman, F. Michael and Davis, Denise and Bogan, Arthur E. and Kwak, Thomas J. and Cope, W. Gregory and Levine, Jay F.}, year={2008}, pages={396–402} }
 @inbook{hayes_bence_kwak_thompson_2007, title={Abundance, biomass, and production estimation}, ISBN={1888569778}, booktitle={Analysis and interpretation of freshwater fisheries data}, publisher={Bethesda, MD: American Fisheries Society}, author={Hayes, D. B. and Bence, J. R. and Kwak, T. J. and Thompson, B. E.}, editor={Guy, C. S. and Brown, M. L.Editors}, year={2007}, pages={327–374} }
 @inbook{kwak_peterson_2007, title={Community indices, parameters, and comparisons}, ISBN={1888569778}, booktitle={Analysis and interpretation of freshwater fisheries data}, publisher={Bethesda, MD: American Fisheries Society}, author={Kwak, T. J. and Peterson, J. T.}, editor={Guy, C. S. and Brown, M. L.Editors}, year={2007}, pages={677–763} }
 @article{holliman_kwak_cope_levine_2007, title={Exposure of Unionid Mussels to Electric Current: Assessing Risks Associated with Electrofishing}, volume={136}, ISSN={0002-8487 1548-8659}, url={http://dx.doi.org/10.1577/T07-006.1}, DOI={10.1577/T07-006.1}, abstractNote={AbstractElectric current is routinely applied in freshwater for scientific sampling of fish populations (i.e., electrofishing). Freshwater mussels (families Margaritiferidae and Unionidae) are distributed worldwide, but their recent declines in diversity and abundance constitute an imperilment of global significance. Freshwater mussels are not targeted for capture by electrofishing, and any exposure to electric current is unintentional. The effects of electric shock are not fully understood for mussels but could disrupt vital physiological processes and represent an additional threat to their survival. In a controlled laboratory environment, we examined the consequences of exposure to two typical electrofishing currents, 60‐Hz pulsed DC and 60‐Hz AC, for the survival of adult and early life stages of three unionid species; we included fish as a quality control measure. The outcomes suggest that electrical exposure associated with typical electrofishing poses little direct risk to freshwater mussels. That is, adult mussel survival and righting behaviors (indicators of sublethal stress) were not adversely affected by electrical exposure. Glochidia (larvae that attach to and become parasites on fish gills or fins) showed minimal immediate reduction in viability after exposure. Metamorphosis from glochidia to free‐living juvenile mussels was not impaired after electric current simulated capture‐prone behaviors (stunning) in infested host fish. In addition, the short‐term survival of juvenile mussels was not adversely influenced by exposure to electric current. Any minimal risk to imperiled mussels must be weighed at the population level against the benefits gained by using the gear for scientific sampling of fish in the same waters. However, scientists sampling fish by electrofishing should be aware of mussel reproductive periods and processes in order to minimize the harmful effects to host fish, especially in areas where mussel conservation is a concern.}, number={6}, journal={Transactions of the American Fisheries Society}, publisher={Wiley}, author={Holliman, F. Michael and Kwak, Thomas J. and Cope, W. Gregory and Levine, Jay F.}, year={2007}, month={Nov}, pages={1593–1606} }
 @article{pine_kwak_rice_2007, title={Modeling management scenarios and the effects of an introduced apex predator on a coastal riverine fish community}, volume={136}, ISSN={["1548-8659"]}, DOI={10.1577/T05-249.1}, abstractNote={AbstractThe flathead catfishPylodictis olivaris, a carnivorous fish species native to most of the central interior basin of North America, has been introduced into at least 13 U.S. states and 1 Canadian province. Concurrent declines in abundance of native fishes have been reported in aquatic systems where flathead catfish have been introduced. To evaluate the potential impact of this invasive species on the native fish community we developed an ecosystem simulation model (including flathead catfish) based on empirical data collected from a North Carolina coastal river. The model results suggest that flathead catfish suppress native fish community biomass by 5–50% through both predatory and competitive interactions. However, our model suggests these reductions could be mitigated through sustained exploitation of flathead catfish by recreational or commercial fishers at rates equivalent to those for native flathead catfish populations (annual exploitation = 6–25%). These findings demonstrate the potential for using directed harvest of an invasive species to assist in restoring native communities.}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Pine, William E., III and Kwak, Thomas J. and Rice, James A.}, year={2007}, month={Jan}, pages={105–120} }
 @misc{kwak_pine_waters_2006, title={Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations}, volume={26}, ISSN={["1548-8675"]}, DOI={10.1577/M04-144.1}, abstractNote={AbstractKnowledge of individual growth and mortality rates of an introduced fish population is required to determine the success and degree of establishment as well as to predict the fish's impact on native fauna. The age and growth of flathead catfish Pylodictis olivaris have been studied extensively in the species' native and introduced ranges, and estimates have varied widely. We quantified individual growth rates and age structure of three introduced flathead catfish populations in North Carolina's Atlantic slope rivers using sagittal otoliths, determined trends in growth rates over time, compared these estimates among rivers in native and introduced ranges, and determined total mortality rates for each population. Growth was significantly faster in the Northeast Cape Fear River (NECFR) than in the Lumber and Neuse rivers. Fish in the NECFR grew to a total length of 700 mm by age 7, whereas fish in the Neuse and Lumber river populations reached this length by 8 and 10 years, respectively. The growth rates of fish in all three rivers were consistently higher than those of native riverine populations, similar to those of native reservoir populations, and slower than those of other introduced riverine populations. In general, recent cohorts (1998–2001 year‐classes) in these three rivers exhibited slower growth among all ages than did cohorts previous to the 1998 year‐class. The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations. Overall, flathead catfish populations in reservoirs grow faster than those in rivers, the growth rates of introduced populations exceed those of native populations, and eastern United States populations grow faster than those in western states. Such trends constitute critical information for understanding and managing local populations.}, number={1}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Kwak, TJ and Pine, WE and Waters, DS}, year={2006}, month={Feb}, pages={73–87} }
 @article{hewitt_cope_kwak_augspurger_lazaro_shea_2006, title={Influence of water quality and associated contaminants on survival and growth of the endangered Cape Fear shiner (Notropis mekistocholas)}, volume={25}, ISSN={["0730-7268"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33750596805&partnerID=MN8TOARS}, DOI={10.1897/05-569r.1}, abstractNote={AbstractThe Cape Fear shiner (Notropis mekistocholas) is a recently described cyprinid species endemic to the Cape Fear River Basin of North Carolina, USA. Only five populations of the fish remain; thus, it is listed as endangered by the U.S. Government. Determining habitat requirements of the Cape Fear shiner, including water quality and physical habitat, is critical to the survival and future restoration of the species. To assess water quality in the best remaining and in the historical habitats, we conducted a 28‐d in situ bioassay with captively propagated Cape Fear shiners. Fish were deployed at 10 sites in three rivers, with three cages per site and 20 fish per cage. Water and sediment samples were collected and analyzed for selected metals and organic contaminants. Passive sampling devices also were deployed at each site and analyzed for organic contaminants at test termination. Fish survival, growth (as measured by an increase in total length), and contaminant accumulation were measured on completion of the bioassay. Survival of caged fish averaged 76% (range, 53–100%) and varied significantly among sites and rivers. Caged fish accumulated quantities of cadmium, mercury, polychlorinated biphenyls, and other persistent contaminants over the test duration and grew significantly at only four sites. No apparent relations were observed between exposure to or accumulation of a specific contaminant and reduced growth or survival of fish among all the sites. However, a generalized hazard assessment showed that certain sites exhibited trends in cumulative contaminant presence with reduced fish survival and growth, thereby enabling the identification of the existing riverine habitat most suitable for reintroduction or population augmentation of this endangered fish.}, number={9}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Hewitt, Amanda H. and Cope, W. Gregory and Kwak, Thomas J. and Augspurger, Tom and Lazaro, Peter R. and Shea, Damian}, year={2006}, month={Sep}, pages={2288–2298} }
 @article{gustafson_showers_kwak_levine_stoskopf_2007, title={Temporal and spatial variability in stable isotope compositions of a freshwater mussel: implications for biomonitoring and ecological studies}, volume={152}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-006-0633-7}, abstractNote={Stable isotopes can be used to elucidate ecological relationships in community and trophic studies. Findings are calibrated against baselines, e.g. from a producer or primary consumer, assumed to act as a reference to the isotopic context created by spatio-temporal attributes such as geography, climate, nutrient, and energy sources. The ability of an organism to accurately represent a community base depends on how, and over what time-scale, it assimilates ambient materials. Freshwater mussels have served as references for trophic studies of freshwater communities and as indicators of change in nutrient pollution load or source. Their suitability as reference animals has not yet been fully explored, however. We conducted a series of studies examining the suitability of freshwater mussels as isotopic baselines, using their ability to reflect variation in ambient nutrient loads as a case scenario. (1) We analyzed bivalve foot tissue delta(15)N and delta(13)C from 22 stream reaches in the Piedmont region of North Carolina, USA to show that compositions varied substantially among locations. Site mean bivalve delta(13)C values correlated with site ambient particulate organic matter (POM) delta(13)C values, and site mean bivalve delta(15)N values correlated with site ambient water dissolved delta(15)N-NO(3) values. (2) Similarity of results among sample types demonstrated that the minimally invasive hemolymph sample is a suitable substitute for foot tissue in delta(15)N analyses, and that small sample sizes generate means representative of a larger population. Both findings can help minimize the impact of sampling on imperiled freshwater mussel populations. (3) In a bivalve transplantation study we showed that hemolymph delta(15)N compositions responded to a shift in ambient dissolved delta(15)N-NO(3), although slowly. The tissue turnover time for bivalve hemolymph was 113 days. We conclude that bivalves serve best as biomonitors of chronic, rather than acute, fluctuations in stream nutrient loads, and provide initial evidence of their suitability as time-integrated isotopic baselines for community studies.}, number={1}, journal={OECOLOGIA}, author={Gustafson, Lori and Showers, William and Kwak, Thomas and Levine, Jay and Stoskopf, Michael}, year={2007}, month={May}, pages={140–150} }
 @article{radwell_kwak_2005, title={Assessing ecological integrity of Ozark rivers to determine suitability for protective status}, volume={35}, ISSN={["1432-1009"]}, DOI={10.1007/s00267-004-0136-4}, abstractNote={Preservation of extraordinary natural resources, protection of water quality, and restoration of impaired waters require a strategy to identify and protect least-disturbed streams and rivers. We applied two objective, quantitative methods to determine stream ecological integrity of headwater reaches of 10 Ozark rivers, 5 with Wild and Scenic River federal protective status. Thirty-four variables representing macroinvertebrate and fish assemblage characteristics, in-stream habitat, riparian vegetation, water quality, and watershed attributes were quantified for each river and analyzed using two multivariate approaches. The first approach, cluster and discriminant analyses, identified two groups of river with only one variable (% forested watershed) reliably distinguishing groups. Our second approach employed ordinal scaling to compare variables for each river to conceptually ideal conditions that were developed as a composite of optimal attributes among the 10 rivers. The composite distance of each river from ideal was then calculated using a unidimensional ranking technique. Two rivers without Wild and Scenic River designation ranked highest relative to ideal (highest ecological integrity), and two others, also without designation, ranked most distant from ideal (lowest ecological integrity). Fish density, number of intolerant fish species, and invertebrate density were influential biotic variables for scaling. Contributing physical variables included riparian forest cover, water nitrate concentration, water turbidity, percentage of forested watershed, percentage of private land ownership, and road density. These methods provide a framework for refinement and application in other regions to facilitate the process of establishing least-disturbed reference conditions and identifying rivers for protection and restoration.}, number={6}, journal={ENVIRONMENTAL MANAGEMENT}, author={Radwell, AJ and Kwak, TJ}, year={2005}, month={Jun}, pages={799–810} }
 @article{heltsley_cope_shea_bringolf_kwak_malindzak_2005, title={Assessing organic contaminants in fish: Comparison of a nonlethal tissue sampling technique to mobile and stationary passive sampling devices}, volume={39}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-26044466979&partnerID=MN8TOARS}, DOI={10.1021/es051037s}, abstractNote={As concerns mount over the human health risks associated with consumption of fish contaminated with persistent organic pollutants, there exists a need to better evaluate fish body burdens without lethally sampling many of the important commercial and sport species of interest. The aim of this study was to investigate two novel methods for estimating organic contaminants in fish that are a concern for both fish and human health. The removal of fish adipose fins, commonly done in mark-recapture studies with salmonid species, was evaluated as a nonlethal sampling technique to estimate concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in flathead catfish (Pylodictis olivaris), relative to those found in muscle fillets of the same fish. We also assessed the efficacy of using poly(dimethylsiloxane) (PDMS) as a mobile passive sampling device (PSD) attached directly to wild flathead catfish for assessing location-specific exposure of the fish to waterborne contaminants. The results of this study have demonstrated for the first time that organic contaminant concentrations in adipose fin were highly correlated (R2 = 0.87) with muscle fillet concentrations, indicating that the adipose fin of certain fishes may be used to accurately estimate tissue concentrations without the need for lethal sampling. Moreover, mobile PSDs attached directly to fish and used here for the first time accurately estimated ultratrace concentrations of waterborne PCBs and OCPs without any apparent harm to the fish, indicating that there are no practical or physical barriers to the use of mobile passive samplers attached to aquatic organisms. Among the many practical implications of this research, two potential priority items include the analysis of organic contaminants in farm-raised and sport fish intended for human consumption, without the economic and population losses associated with lethally sampling fish to obtain tissues, and identifying specific areas where fish may be accumulating large portions of their contaminant burden.}, number={19}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Heltsley, RM and Cope, WG and Shea, D and Bringolf, RB and Kwak, TJ and Malindzak, EG}, year={2005}, month={Oct}, pages={7601–7608} }
 @article{pine_kwak_waters_rice_2005, title={Diet selectivity of introduced flathead catfish in coastal rivers}, volume={134}, ISSN={["1548-8659"]}, DOI={10.1577/T04-166.1}, abstractNote={AbstractIn two coastal North Carolina rivers (Contentnea Creek and the Northeast Cape Fear River), we found the food habits of introduced flathead catfish Pylodictis olivaris to be primarily piscivorous, which could restructure or suppress native fish communities through direct predation. Fish or crayfish contributed more than 50% of the stomach contents by percent occurrence, percent by number, and percent by weight in both rivers during each of 2 years. Significant differences in diet composition (percent by number) were found between rivers and between years in the Northeast Cape Fear River but not between years within Contentnea Creek. Chesson's selectivity index values and trends in relative abundances of fish availability relative to those occurring in the diet suggest that flathead catfish feeding is generally random, indicating that these introduced flathead catfish do not selectively feed on prey species with which they did not coevolve. Our research represents the first assessment of prey selectivity by an introduced ictalurid population and provides evidence of the potential impact on native fish communities through their piscivorous food habits.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Pine, WE and Kwak, TJ and Waters, DS and Rice, JA}, year={2005}, month={Jul}, pages={901–909} }
 @article{gustafson_stoskopf_bogan_showers_kwak_hanlon_levine_2005, title={Evaluation of a nonlethal technique for hemolymph collection in Elliptio complanata, a freshwater bivalve (Mollusca: Unionidae)}, volume={65}, ISSN={0177-5103 1616-1580}, url={http://dx.doi.org/10.3354/dao065159}, DOI={10.3354/dao065159}, abstractNote={Hemolymph, the circulatory fluid of bivalves, transports nutrients, respiratory gases, enzymes, metabolic wastes, and toxicants throughout the body. Hemolymph can provide information pertinent to health assessment of animals or populations, but is not commonly used in freshwater bivalves partly because of the lack of tested, practical techniques for its nonlethal collection. The objective of this study was to evaluate the effect of hemolymph collection on the growth and survival of Elliptio complanata, a freshwater bivalve (Unionidae). We describe a simple technique for the collection of hemolymph from the anterior adductor muscle sinus of E. complanata. To evaluate the effect of hemolymph sampling on mussel survival and growth, 30 mussels sampled using the technique and 30 unsampled controls were followed for 3 mo post collection. Nine animals were sampled 3 times over 7 mo to monitor effects of repeated sampling. No negative impacts on survival or growth were observed in either the singly or repeatedly sampled animals. We also compared the composition of hemolymph collected from the adductor muscle sinus with that collected from the ventricle of the heart. Calcium levels and cell count of hemolymph obtained from the adductor sinus and ventricle were significantly different. There was no significant difference between collection sites for magnesium, phosphorus, ammonia, protein, sodium, potassium, or chloride. We conclude that collection of hemolymph from the adductor sinus is safe for sampled E. complanata and should be explored as a relatively non-invasive, and potentially useful, approach to the evaluation of freshwater mussel health.}, number={2}, journal={Diseases of Aquatic Organisms}, publisher={Inter-Research Science Center}, author={Gustafson, LL and Stoskopf, MK and Bogan, AE and Showers, W and Kwak, TJ and Hanlon, S and Levine, JF}, year={2005}, pages={159–165} }
 @article{brown_perillo_kwak_horwitz_2005, title={Implications of Pylodictis olivaris (flathead catfish) introduction into the Delaware and Susquehanna drainages}, volume={12}, ISSN={["1938-5307"]}, DOI={10.1656/1092-6194(2005)012[0473:IOPOFC]2.0.CO;2}, abstractNote={Abstract Pylodictis olivaris (flathead catfish) is a large, obligate carnivore native to drainages of the central United States that has been introduced widely beyond its native range. We report on the introduction of flathead catfish into the Delaware and Susquehanna River drainages, which represents the northernmost occurrences among Atlantic drainages. In the Delaware Basin, flathead catfish have been found in the Schuylkill River and the mainstem of the Delaware River. Recent sampling activities in the Schuylkill River suggest successful reproduction and establishment of a viable population there. In the Susquehanna basin, the fish has been found in the lower and central portion of the river mainstem. As in the Delaware Basin, recent sampling indicates that reproduction is occurring in the Susquehanna River. The introduction of this species has the potential to adversely affect ongoing anadromous fish restoration programs and native fish conservation efforts in the Delaware and Susquehanna basins. A cooperative effort will be required to mitigate the effects of this introduction.}, number={4}, journal={NORTHEASTERN NATURALIST}, author={Brown, JJ and Perillo, J and Kwak, TJ and Horwitz, RJ}, year={2005}, pages={473–484} }
 @article{gustafson_stoskopf_showers_cope_eads_linnehan_kwak_andersen_levine_2005, title={Reference ranges for hemolymph chemistries from Elliptio complanata of North Carolina}, volume={65}, ISSN={["1616-1580"]}, DOI={10.3354/dao065167}, abstractNote={Hemolymph chemistries may be useful nonlethal measures of bivalve health. The prognostic value of hemolymph, however, depends on a comparison of chemistry results to reference ranges from healthy individuals. Currently, knowledge of expected hemolymph values in healthy and unhealthy freshwater mussels is extremely limited. The purpose of this study was to develop a set of reference ranges for clinical evaluation of hemolymph from a freshwater mussel species common to southeastern USA. We collected hemolymph from 380 Elliptio complanata from 19 apparently healthy populations from northwest of Raleigh, North Carolina, during May through July 2001. We present reference ranges for hemolymph parameters ammonia, glucose, calcium, magnesium, phosphorus, aspartate aminotransferase (AST), bicarbonate, protein and cell count, and for tissue glycogen. We compare the subpopulations of mussels from regions with an agricultural riparian buffer to those surrounded predominantly by forested lands. We further present correlations noted between hemolymph chemistries and physical or physiologic parameters. The only statistically significant differences between populations contiguous to agricultural and forested lands were in hemolymph calcium and glucose concentrations. Other statistically significant correlations identified were between gravidity and hemolymph protein concentration and tissue glycogen content, as well as between gravidity and parasite burden, and between shell length and hemolymph glucose, AST, calcium and bicarbonate concentrations. The results of this study will aid the interpretation of health measures from populations of E. complanata of similar geographic and seasonal origin.}, number={2}, journal={DISEASES OF AQUATIC ORGANISMS}, author={Gustafson, LL and Stoskopf, MK and Showers, W and Cope, G and Eads, C and Linnehan, R and Kwak, TJ and Andersen, B and Levine, JF}, year={2005}, month={Jun}, pages={167–176} }
 @article{bringolf_kwak_cope_larimore_2005, title={Salinity tolerance of flathead catfish: Implications for dispersal of introduced populations}, volume={134}, ISSN={["0002-8487"]}, DOI={10.1577/T04-195.1}, abstractNote={AbstractThe flathead catfish Pylodictis olivaris is a large predatory fish that has been introduced widely beyond its indigenous range to the detriment of many native fish communities. It disperses rapidly within and among river systems, but its potential to use saltwater or brackish waters for migration and exploitation of marine prey resources is unknown. We evaluated the salinity tolerance of juvenile flathead catfish exposed to NaCl and synthetic seawater (0–34‰) in direct‐transfer acute toxicity tests. The 96‐h median lethal concentration (LC50) for fish exposed to NaCl at 18°C was a salinity of 10.0‰ with a 95% confidence interval (CI) of 9.0–11.1‰, whereas the 96‐h LC50 for fish in synthetic seawater (Instant Ocean) at 18°C was 14.5‰ (95% CI, 13.7–15.5‰). To determine whether fish could survive the transition from freshwater to brackish water and then back to freshwater, fish were transferred from freshwater at 18°C to water with a salinity of 8, 11, or 14‰ for 24 h and then returned to freshwater for 48 h. Fish exposed to synthetic seawater with a salinity of 8 or 11‰ for 24 h had more than 95% survival for 48 h after transfer to freshwater; however, no fish transferred directly to synthetic seawater with a salinity of 14‰ survived the 24‐h exposure period. Additional acclimation tests with fish that were exposed to synthetic seawater in which salinity was increased daily by 4‰ yielded an LC50 of 15.8‰. Our results provide evidence that flathead catfish could tolerate exposure to many brackish waters along the Atlantic and Gulf of Mexico coasts of the United States and that the dispersal of introduced flathead catfish populations among rivers may not be limited by estuarine salinities.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Bringolf, RB and Kwak, TJ and Cope, WG and Larimore, MS}, year={2005}, month={Jul}, pages={927–936} }
 @article{waters_kwak_arnott_pine_2004, title={Evaluation of stomach tubes and gastric lavage for sampling diets from blue catfish and flathead catfish}, volume={24}, ISSN={["0275-5947"]}, DOI={10.1577/M02-156}, abstractNote={Abstract We compared the ability to extract all stomach contents by using stomach tubes or gastric lavage to sample diets from blue catfish Ictalurus furcatus and flathead catfish Pylodictis olivaris. Pulsed gastric lavage (PGL) removed a significantly greater proportion of stomach content mass (95.6%) from blue catfish than did stomach tubes (14.6%). Percent mass of flathead catfish contents removed with PGL (96.0%) was not significantly different from that removed with stomach tubes (86.9%). Based on the greater effectiveness of PGL for blue catfish, combined with a shorter mean time required per sample (69 versus 118 s) and the better preservation of extracted diet material, we recommend using PGL as a nonlethal technique to collect diet samples from large catfishes.}, number={1}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Waters, DS and Kwak, TJ and Arnott, JB and Pine, WE}, year={2004}, month={Feb}, pages={258–261} }
 @article{barwick_kwak_noble_barwick_2004, title={Fish populations associated with habitat-modified piers and natural woody debris in Piedmont Carolina reservoirs}, volume={24}, ISSN={["1548-8675"]}, DOI={10.1577/m03-094.1}, abstractNote={Abstract A primary concern associated with reservoir shoreline residential development is reduction of littoral habitat complexity and diversity. One potential approach to compensate for this is the deployment of artificial-habitat modules under existing piers, but the benefit of this practice has not been demonstrated. To evaluate the effect of pier habitat modifications on fish populations in two Piedmont Carolina reservoirs, we studied 77 piers located on forty-seven, 100-m transects that were modified using plastic “fish hab” modules augmented with brush (brushed habs), hab modules alone (habs), or left unaltered for reference purposes. We sampled fish from all piers and transects during April, July, and October 2001 using a boat-mounted electrofisher. With few exceptions, catch rates were higher at brushed-hab piers and piers with habs than at reference piers during all seasons. Similarly, during spring and summer, fish abundance was generally higher on transects containing natural woody debris, brus...}, number={4}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Barwick, RD and Kwak, TJ and Noble, RL and Barwick, DH}, year={2004}, month={Nov}, pages={1120–1133} }
 @article{holliman_reynolds_kwak_2003, title={A predictive risk model for electroshock-induced mortality of the endangered cape fear shiner}, volume={23}, ISSN={["0275-5947"]}, DOI={10.1577/M02-009}, abstractNote={Abstract We evaluated the effects of a single electroshock on injury and mortality of hatchery-reared Cape Fear shiners Notropis mekistocholas (N = 517), an endangered cyprinid. Groups of 18-22 Cape Fear shiners were exposed to DC, 120-Hz pulsed DC (PDC), or 60-Hz PDC at voltage gradients of 1.1, 1.9, or 2.7 V/cm for 3 s. Mortality occurred only among fish exposed to 120-Hz PDC (25%) and DC (38%) applied at 2.7 V/cm. Because no mortality occurred in Cape Fear shiners exposed to 60-Hz PDC, this waveform was selected for further study of electroshock duration (3, 6, 12, 24, or 48 s) and voltage gradient (0.9, 1.6, or 2.3 V/cm). Most fish electroshocked in the experiments were immobilized (ceased swimming motion). No physical injury was detected by necropsy or radiography in any fish. Electroshock-induced mortality of Cape Fear shiners showed a strong multivariable relationship to voltage gradient, electroshock duration, and fish length. Fish subjected to 60-Hz PDC at 0.9 or 1.6 V/cm for 6 s experienced low ...}, number={3}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Holliman, FM and Reynolds, JB and Kwak, TJ}, year={2003}, month={Aug}, pages={905–912} }
 @misc{pine_pollock_hightower_kwak_rice_2003, title={A review of tagging methods for estimating fish population size and components of mortality}, volume={28}, ISSN={["1548-8446"]}, DOI={10.1577/1548-8446(2003)28[10:AROTMF]2.0.CO;2}, abstractNote={Abstract Techniques to improve estimation of animal population size and mortality from tagging studies have received substantial attention from terrestrial biologists and statisticians during the last 20 years. However, these techniques have received little notice from fisheries biologists, despite the widespread applicability to fisheries research, the wide variety of tag types used in fisheries research (from traditional fin clips to telemetry tags), and the development of new computer software to assist with analyses. We present a brief review of population models based on recaptures, returns, or telemetry relocations of tagged fish that can be used to estimate population size, total mortality, and components of mortality (i.e., fishing and natural) that are frequently of interest to fisheries biologists. Recommended strategies include (1) use closed population models (e.g., Lincoln-Peterson) to estimate population size for short term studies where closure assumption can be met, (2) use the robust desi...}, number={10}, journal={FISHERIES}, author={Pine, WE and Pollock, KH and Hightower, JE and Kwak, TJ and Rice, JA}, year={2003}, month={Oct}, pages={10–23} }
 @article{holliman_reynolds_kwak_2003, title={Electroshock-induced injury and mortality in the spotfin chub, a threatened minnow}, volume={23}, ISSN={["0275-5947"]}, DOI={10.1577/M02-052}, abstractNote={Abstract The effects of AC and pulsed DC (PDC) electroshock on mortality and injury (vertebral damage and hemorrhage) of spotfin chub Cyprinella monacha, a threatened minnow, were evaluated in a laboratory experiment. Groups of 18-20 captive-reared fish were either designated as a control or exposed for 3 s to one of five electrical treatments (60-Hz AC at a peak-to-peak voltage gradient of 1.7, 2.5, or 3.3 V/cm or 60-Hz PDC at a peak voltage gradient of 2.5 or 5.0 V/cm). Immobilization, which renders fish susceptible to capture during electrofishing, was the predominant response evoked in the groups exposed to electroshock, with the exception of the 1.7-V/cm AC group. No injury was detected in any fish in the experiment. Mortality was 10% or less in groups exposed to AC, regardless of voltage gradient. There was no significant variation in mortality among the groups exposed to AC (P = 0.487-1.00). Mortality varied significantly in the groups exposed to 60-Hz PDC (2.5 V/cm (0%) versus 5.0 V/cm (25%); P = ...}, number={3}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Holliman, FM and Reynolds, JB and Kwak, TJ}, year={2003}, month={Aug}, pages={962–966} }
 @article{quinn_kwak_2003, title={Fish assemblage changes in an Ozark river after impoundment: A long-term perspective}, volume={132}, ISSN={["0002-8487"]}, DOI={10.1577/1548-8659(2003)132<0110:FACIAO>2.0.CO;2}, abstractNote={Abstract We conducted an intensive fish survey in the tailwater reach of a large Ozark river 30 years after its impoundment and compared the recent fish assemblage with those prior to impoundment and shortly (4 years) after impoundment. Our primary objective was to assess whether relatively short-term monitoring following dam construction can adequately quantify the long-term effects of impoundment on downstream riverine fishes. The preimpoundment survey (1962–1963) described a fish assemblage composed of warmwater fish species, predominantly Cyprinidae, Ictaluridae, Centrarchidae, and Percidae. Yoke darter Etheostoma juliae (34%), central stoneroller Campostoma anomalum (24%), and Ozark madtom Noturus albater (7%) were the most abundant species. The postimpoundment surveys of 1965–1966 and 1968 documented immediate changes in the fish assemblage. No Ozark madtoms and only four yoke darters were collected shortly after impoundment. Central stonerollers accounted for 45–50% of the fish collected, and both ...}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Quinn, JW and Kwak, TJ}, year={2003}, month={Jan}, pages={110–119} }
 @misc{pender_kwak_2002, title={Factors influencing brown trout reproductive success in Ozark tailwater rivers}, volume={131}, ISSN={["1548-8659"]}, DOI={10.1577/1548-8659(2002)131<0698:FIBTRS>2.0.CO;2}, abstractNote={Abstract The reproductive success of brown trout Salmo trutta in White River, Arkansas, tailwater reaches is highly variable, resulting in the need for supplemental stocking. A better understanding of the physical and biotic factors affecting reproduction and survival would enhance the contribution of wild fish. We compared fecundity, reproductive chronology, physical habitat, water quality, trout density, food availability, diet, predation, and competitive interactions among four tailwater reaches to identify factors influencing brown trout reproductive success. The fecundity and condition factor of prespawning brown trout were significantly lower at Beaver Tailwater, a reach known for reproductive failure, than at other sites, among which no differences were found. Brown trout spawning was observed from 11 October to 23 November 1996, and juvenile emergence began on 28 February 1997. Significant among-site differences were detected for spawning and juvenile microhabitat variables, but the variables fell...}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Pender, DR and Kwak, TJ}, year={2002}, month={Jul}, pages={698–717} }
 @article{quinn_kwak_2000, title={Use of rehabilitated habitat by brown trout and rainbow trout in an Ozark tailwater river}, volume={20}, DOI={10.1577/1548-8675(2000)020<0737:uorhbb>2.3.co;2}, abstractNote={Abstract We evaluated instream and riparian habitat rehabilitation that was completed following catastrophic flooding in the White River, below Beaver Dam, Arkansas. Most rehabilitation structures were designed to stabilize the river banks and increase cover for trout (Salmonidae) during high flows associated with hydroelectric power generation. We quantified trout response to rehabilitation at two spatial scales—microhabitat and river reach. At the microhabitat scale, brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss occupied the deepest habitats available and were randomly associated with cover at low flow (about 1 m3/s). Principal-component scores describing physical characteristics of brown trout and rainbow trout microhabitats were significantly different from available-habitat scores at high flow (about 215 m3/s), when trout were strongly associated with velocity refugia near the river margins—habitats similar to those created by rehabilitation structures. At the reach scale, trout popu...}, journal={North American Journal of Fisheries Management}, author={Quinn, J. W. and Kwak, Thomas}, year={2000}, pages={737–751} }
 @article{peterson_kwak_1999, title={Modeling the effects of land use and climate change on riverine smallmouth bass}, volume={9}, ISSN={["1051-0761"]}, DOI={10.1890/1051-0761(1999)009[1391:mteolu]2.0.co;2}, abstractNote={Anthropogenic changes in temperature and stream flow, associated with watershed land use and climate change, are critical influences on the distribution and abundance of riverine fishes. To project the effects of changing land use and climate, we modeled a smallmouth bass (Micropterus dolomieu) population in a midwestern USA, large river–floodplain ecosystem under historical (1915–1925), present (1977–1990), and future (2060, influenced by climate change) temperature and flow regimes. The age-structured model included parameters for temperature and river discharge during critical seasonal periods, fish population dynamics, and fishing harvest. Model relationships were developed from empirical field data collected over a 13-yr period. Sensitivity analyses indicated that discharge during the spawning/rearing period had a greater effect on adult density and fishing yield than did spawning/rearing temperature or winter discharge. Simulations for 100 years projected a 139% greater mean fish density under a historical flow regime (64.9 fish/ha) than that estimated for the present (27.1 fish/ha) with a sustainable fishing harvest under both flow regimes. Simulations under future climate-change-induced temperature and flow regimes with present land use projected a 69% decrease in mean fish density (8.5 fish/ha) from present and an unstable population that went extinct during 56% of the simulations. However, when simulated under a future climate-altered temperature and flow regime with historical land use, the population increased by 66% (45.0 fish/ha) from present and sustained a harvest. Our findings suggest that land-use changes may be a greater detriment to riverine fishes than projected climate change and that the combined effects of both factors may lead to local species extinction. However, the negative effects of increased temperature and precipitation associated with future global warming could be mitigated by river channel, floodplain, and watershed restoration.}, number={4}, journal={ECOLOGICAL APPLICATIONS}, author={Peterson, JT and Kwak, TJ}, year={1999}, month={Nov}, pages={1391–1404} }
 @article{kwak_zedler_1997, title={Food web analysis of southern California coastal wetlands using multiple stable isotopes}, volume={110}, ISSN={["0029-8549"]}, DOI={10.1007/s004420050159}, abstractNote={Carbon, nitrogen, and sulfur stable isotopes were used to characterize the food webs (i.e., sources of carbon and trophic status of consumers) in Tijuana Estuary and San Dieguito Lagoon. Producer groups were most clearly differentiated by carbon, then by sulfur, and least clearly by nitrogen isotope measurements. Consumer 15N isotopic enrichment suggested that there are four trophic levels in the Tijuana Estuary food web and three in San Dieguito Lagoon. A significant difference in multiple isotope ratio distributions of fishes between wetlands suggested that the food web of San Dieguito Lagoon is less complex than that of Tijuana Estuary. Associations among sources and consumers indicated that inputs from intertidal macroalgae, marsh microalgae, and Spartina foliosa provide the organic matter that supports invertebrates, fishes, and the light-footed clapper rail (Rallus longirostris levipes). These three producers occupy tidal channels, low salt marsh, and mid salt marsh habitats. The only consumer sampled that appears dependent upon primary productivity from high salt marsh habitat is the sora (Porzana carolina). Two- and three-source mixing models identified Spartina as the major organic matter source for fishes, and macroalgae for invertebrates and the light-footed clapper rail in Tijuana Estuary. In San Dieguito Lagoon, a system lacking Spartina, inputs of macroalgae and microalgae support fishes. Salicornia virginica, S. subterminalis, Monanthochloe littoralis, sewage- derived organic matter, and suspended particulate organic matter were deductively excluded as dominant, direct influences on the food web. The demonstration of a salt marsh–channel linkage in these systems affirms that these habitats should be managed as a single ecosystem and that the restoration of intertidal marshes for endangered birds and other biota is compatible with enhancement of coastal fish populations; heretofore, these have been considered to be competing objectives.}, number={2}, journal={OECOLOGIA}, author={Kwak, TJ and Zedler, JB}, year={1997}, month={Apr}, pages={262–277} }
 @article{kwak_waters_1997, title={Trout production dynamics and water quality in Minnesota streams}, volume={126}, ISSN={["1548-8659"]}, DOI={10.1577/1548-8659(1997)126<0035:TPDAWQ>2.3.CO;2}, abstractNote={Abstract We sampled fish assemblages and quantified production dynamics of brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss in 13 southeastern Minnesota streams during 1988–1990 to examine the influence of water quality on fish populations in fertile trout streams. Fish assemblages in 15 stream reaches were abundant, but low in diversity; 13 species were collected. Parameter means (ranges) over the reaches were species richness, 4.1 (1–8); density, 29,490 (1,247–110,602) fish/ha; and biomass, 253.5 (49.6–568.6) kg/ha. Means (ranges) for salmonids were annual mean density, 2,279 (343–8,096) fish/ha; annual mean biomass, 162.0 (32.5–355.5) kg/ha; and annual production, 155.6 (36.7–279.6) kg/ha. Salmonid production and mean biomass were greater during the spring-fall interval than during fall-spring; young cohorts (ages 0–1) contributed the greatest proportion to population biomass and production. Salmonid annual production-to-mean-biomass ratio (P/B) average...}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Kwak, TJ and Waters, TF}, year={1997}, month={Jan}, pages={35–48} }
 @article{largemouth bass mortality and related causal factors during live-release fishing tournaments on a large minnesota lake_1995, volume={15}, DOI={10.1577/1548-8675(1995)015<0621:lbmarc>2.3.co;2}, abstractNote={Abstract We quantified initial and delayed mortality of largemouth bass Micropterus salmoides during live-release fishing tournaments and identified probable causes of death in order to provide a biological basis for refining tournament guidelines and regulation. Mean estimates for two tournaments on Lake Minnetonka, Minnesota, were 1.42% weigh-in mortality, 3.35% 3-d delayed mortality, and 4.72% total mortality. Catch and total mortality rates during a May tournament were both over 1.5 times those of a September tournament, the difference presumably being related to reproductive behavior and condition. Tournament mortality of the population was minimal relative to other causes of mortality; total tournament mortality estimates for 1992 (11 tournaments) represented 2.3–6.3% of angling mortality and 1.3–3.0% of total mortality in Lake Minnetonka. Means of all water quality variables measured in live wells were significantly different from those of lake water, and relative differences were greatest for ammo...}, journal={North American Journal of Fisheries Management}, year={1995}, pages={621–630} }
 @article{waters_kaehler_polomis_kwak_1993, title={PRODUCTION DYNAMICS OF SMALLMOUTH BASS IN A SMALL MINNESOTA STREAM}, volume={122}, ISSN={["1548-8659"]}, DOI={10.1577/1548-8659(1993)122<0588:PDOSBI>2.3.CO;2}, abstractNote={Abstract Annual production by smallmouth bass Micropterus dolomieu in Bear Creek, Minnesota, was 43.8 and 24.1 kg wet weight per hectare in 1985–1986 and 1987–1988, respectively. Corresponding annual production/biomass ratios were 1.6 and 0.9. Densities and standing stocks changed little between years. Twenty-five additional fish species were present in Bear Creek. Age-0 smallmouth bass (shorter than 11 cm total length) fed most heavily on corixids, whereas older, larger fish fed most heavily on other fishes. Annual production by smallmouth bass was much lower than trout production in similarly fertile streams in southern Minnesota and Wisconsin. This lower production may be attributable to the many more coexisting fishes with which the smallmouth bass must share the food resources of its habitat. More-restrictive creel regulations may be needed for smallmouth bass than for trout, even in streams of similar basic productivity.}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={WATERS, TF and KAEHLER, JP and POLOMIS, TJ and KWAK, TJ}, year={1993}, month={Jul}, pages={588–598} }
 @inbook{kwak_1993, title={The Kankakee River: a case study and management recommendations for a stream diverse in habitat, fauna, and human values}, booktitle={Restoration planning for the rivers of the Mississippi River ecosystem}, publisher={Washington, DC: U.S. National Biological Survey}, author={Kwak, T. J.}, editor={L. W. Hesse, C. B. Stalnaker and N. G. Benson and Zuboy, J. R.Editors}, year={1993}, pages={123–141} }
 @article{kwak_wiley_osborne_larimore_1992, title={APPLICATION OF DIEL FEEDING CHRONOLOGY TO HABITAT SUITABILITY ANALYSIS OF WARMWATER STREAM FISHES}, volume={49}, ISSN={["0706-652X"]}, DOI={10.1139/f92-157}, abstractNote={ Diel feeding chronology and daily ration were determined from stomach or foregut contents of common carp (Cyprinus carpio), golden redhorse (Moxostoma erythrurum), channel catfish (Ictalurus punctatus), smallmouth bass (Micropterus dolomieu), and longear sunfish (Lepomis megalotis) in the Vermilion River, Illinois. Feeding was highly variable among individuals, hours, and months for each species. Discontinuous feeding was detected in common carp, golden redhorse, and channel catfish. Common carp and the two centrarchid species fed with greatest intensity near sunrise and sunset; golden redhorse and channel catfish feeding was highest at night. Daily ration estimates were higher for fishes with stomachs than those for stomachless species. Microhabitats occupied by fish over the diel period were identified using nondisruptive techniques: direct observation, prepositioned electrofishing, and radiotelemetry. Microhabitat use during high-feeding periods was significantly different [Formula: see text] than that during low feeding for at least one habitat variable in each species examined. Association with cover also varied between feeding regimes. Our findings suggest that realism of instream flow assessments may be improved if habitat suitability criteria are stratified by feeding regime. }, number={7}, journal={CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES}, author={KWAK, TJ and WILEY, MJ and OSBORNE, LL and LARIMORE, RW}, year={1992}, month={Jul}, pages={1417–1430} }
 @article{kwak_1992, title={Modular microcomputer software to estimate fish population parameters, production rates and associated variance}, volume={1}, DOI={10.1111/j.1600-0633.1992.tb00009.x}, abstractNote={Abstract– Microcomputer software to estimate fish population parameters, production rates, and associated variances was developed using established procedures. Pop/Pro Modular Statistical Software is a series of portable programs written in English that run on Macintosh(R) or IBM(R) (and compatible) computers. Population parameters can be estimated using either a single‐census mark‐recapture method or a removal method. Production and component parameters can be estimated with either the instantaneous growth rate method or the increment summation method. Output may be stratified by fish length, age or sampling interval and includes variance estimates for all parameters. The software was developed for use with fish data but may be applicable to other taxa.}, journal={Ecology of Freshwater Fish}, author={Kwak, Thomas}, year={1992}, pages={73–75} }
 @article{kwak_skelly_1992, title={SPAWNING HABITAT, BEHAVIOR, AND MORPHOLOGY AS ISOLATING MECHANISMS OF THE GOLDEN REDHORSE, MOXOSTOMA-ERYTHRURUM, AND THE BLACK REDHORSE, M-DUQUESNEI, 2 SYNTOPIC FISHES}, volume={34}, ISSN={["0378-1909"]}, DOI={10.1007/BF00002388}, abstractNote={Golden redhorse, Moxostoma erythrurum, and black redhorse, M. duquesnei, were observed spawning during the springs of 1984 through 1987 in Stony Creek, Illinois, at water temperatures ranging from 15–21°C. Both species spawned simultaneously within the same stream reach in 1987. Male golden redhorse aggressively defended territories on shoals and were joined by females from an adjacent pool. Black redhorse also spawned in riffles and displayed no agonistic behavior. Both species spawned throughout daylight hours in groups of two to five, and golden redhorse also spawned at night. Habitat utilization curves indicate that black redhorse spawned in habitat that was slightly deeper, much swifter, and over coarser substrate than that of the golden redhorse. Males of both species exhibited nuptial body color and breeding tubercles on anal and caudal fins, while only golden redhorse males had head tubercles. We suggest that these differences in spawning habitat, behavior, and morphology act as reproductive isolating mechanisms between the species and that the dichotomy in habitat and behavior may be due to competitive interactions.}, number={2}, journal={ENVIRONMENTAL BIOLOGY OF FISHES}, author={KWAK, TJ and SKELLY, TM}, year={1992}, month={Jun}, pages={127–137} }
 @article{kwak_1991, title={ECOLOGICAL CHARACTERISTICS OF A NORTHERN POPULATION OF THE PALLID SHINER}, volume={120}, ISSN={["1548-8659"]}, DOI={10.1577/1548-8659(1991)120<0106:ECOANP>2.3.CO;2}, abstractNote={Abstract The pallid shiner Notropis amnis, a rare minnow with an unknown life history, was collected from the Kankakee River, Illinois, over a 9-year period (1978–1986). The total length (L, mm)-weight (W, g) relationship for 88 specimens was log10 W = –4.97 + 2.87(log10 L). Condition factors (K = 105 W/L 3; mean, 0.69; range, 0.53–0.83) for specimens collected in July and August showed no trend by size and were lower than those of specimens collected in November. The annual catch per unit effort of juvenile pallid shiners (≤36 mm TL) was positively correlated with minimum flows in May and June, and negatively correlated with March air temperatures. The total catch was positively related to March maximum flow. Habitat suitability curves indicate that this species occurs in shallow areas with little or no current velocity and in moderately clear waters that are average in pH and warm and well oxygenated in summer. Juvenile pallid shiners occurred in shallower and more turbid waters than adults. Pallid shin...}, number={1}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={KWAK, TJ}, year={1991}, month={Jan}, pages={106–115} }
 @article{kwak_1988, title={LATERAL MOVEMENT AND USE OF FLOODPLAIN HABITAT BY FISHES OF THE KANKAKEE RIVER, ILLINOIS}, volume={120}, ISSN={["0003-0031"]}, DOI={10.2307/2425995}, abstractNote={-Fishes were trapped moving between the river channel and two distinct floodplain habitats: an ephemeral ditch and a permanent pool. Twenty-five fish species were sampled by one-way traps and seine; dominant species were grass pickerel (Esox americanus), green sunfish (Lepomis cyanellus), pirate perch (Aphredoderus sayanus) and orangespotted sunfish (L. humilis). Numbers of fish trapped per day were positively correlated with river discharge yielding a significant exponential relationship. Recaptures of marked fish were rare indicating seasonal use of the floodplain. Juveniles made up 54.7% of the fish collected, revealing the value of floodplains as nursery areas. No significant migration trends of size or taxon occurred by date or discharge. Samples of fish leaving the ephemeral ditch and samples of those entering the permanent pool showed the highest similarity index value. These data suggest that flood-exploitative fishes, those species adapted to flooding, continue to seek favorable backwater habitat when forced off the floodplain.}, number={2}, journal={AMERICAN MIDLAND NATURALIST}, author={KWAK, TJ}, year={1988}, month={Oct}, pages={241–249} }