@article{dunn_schumann_colvin_sleezer_wagner_jones-farrand_rivenbark_mcrae_evans_2024, title={Using resiliency, redundancy, and representation in a Bayesian belief network to assess imperilment of riverine fishes}, volume={15}, ISSN={["2150-8925"]}, url={http://dx.doi.org/10.1002/ecs2.4738}, DOI={10.1002/ecs2.4738}, abstractNote={AbstractConservation prioritization frameworks are used worldwide to identify species at greatest risk of extinction and to allocate limited resources across regions, species, and populations. Conservation prioritization can be impeded by ecological knowledge gaps and data deficiency, especially in freshwater species inhabiting highly complex aquatic ecosystems. Therefore, we developed a flexible approach that calculates a species' imperilment risk based on the conservation principles of resiliency, redundancy, and representation (i.e., the “three R's”). Our approach organizes data on species traits, distributions, population connectivity, and threats within a Bayesian belief network capable of predicting resiliency and redundancy within representative ecological settings. Empirical data and expert judgment inform the model to provide robust and repeatable risk assessments for rare and data‐deficient species. The model calculates resiliency at hierarchical spatial scales from distributional trends and population strength. Redundancy is estimated from the connectivity and quantities of extant populations. Resiliency, redundancy, and species' inherent vulnerability based on species traits collectively estimate extirpation risk within each unique ecological setting. Extirpation risks across ecological settings characterize representation and are aggregated to estimate global imperilment risk. We demonstrate the model's utility with Piebald Madtom (Noturus gladiator), a species petitioned for listing under the U.S. Endangered Species Act. Our results revealed that resiliency, redundancy, and extirpation risks can vary spatially across the species' range while identifying populations where additional sampling could disproportionally reduce uncertainty in estimated global imperilment risk. Our approach could standardize and expedite conservation status assessments, identify opportunities for early management intervention of at‐risk species and populations, and strategically reduce uncertainty by focusing monitoring and research on priority information gaps.}, number={1}, journal={ECOSPHERE}, author={Dunn, Corey G. and Schumann, David A. and Colvin, Michael E. and Sleezer, Logan J. and Wagner, Matthew and Jones-Farrand, D. Todd and Rivenbark, Erin and Mcrae, Sarah and Evans, Kristine}, year={2024}, month={Jan} }
 @article{bouska_healy_moore_dunn_spurgeon_paukert_2023, title={Diverse portfolios: Investing in tributaries for restoration of large river fishes in the Anthropocene}, volume={11}, url={http://dx.doi.org/10.3389/fenvs.2023.1151315}, DOI={10.3389/fenvs.2023.1151315}, abstractNote={Rehabilitation of large Anthropocene rivers requires engagement of diverse stakeholders across a broad range of sociopolitical boundaries. Competing objectives often constrain options for ecological restoration of large rivers whereas fewer competing objectives may exist in a subset of tributaries. Further, tributaries contribute toward building a “portfolio” of river ecosystem assets through physical and biological processes that may present opportunities to enhance the resilience of large river fishes. Our goal is to review roles of tributaries in enhancing mainstem large river fish populations. We present case histories from two greatly altered and distinct large-river tributary systems that highlight how tributaries contribute four portfolio assets to support large-river fish populations: 1) habitat diversity, 2) connectivity, 3) ecological asynchrony, and 4) density-dependent processes. Finally, we identify future research directions to advance our understanding of tributary roles and inform conservation actions. In the Missouri River United States, we focus on conservation efforts for the state endangered lake sturgeon, which inhabits large rivers and tributaries in the Midwest and Eastern United States. In the Colorado River, Grand Canyon United States, we focus on conservation efforts for recovery of the federally threatened humpback chub. In the Missouri River, habitat diversity focused on physical habitats such as substrate for reproduction, and deep-water habitats for refuge, whereas augmenting habitat diversity for Colorado River fishes focused on managing populations in tributaries with minimally impaired thermal and flow regimes. Connectivity enhancements in the Missouri River focused on increasing habitat accessibility that may require removal of physical structures like low-head dams; whereas in the Colorado River, the lack of connectivity may benefit native fishes as the disconnection provides refuge from non-native fish predation. Hydrologic variability among tributaries was present in both systems, likely underscoring ecological asynchrony. These case studies also described density dependent processes that could influence success of restoration actions. Although actions to restore populations varied by river system, these examples show that these four portfolio assets can help guide restoration activities across a diverse range of mainstem rivers and their tributaries. Using these assets as a guide, we suggest these can be transferable to other large river-tributary systems.}, journal={Frontiers in Environmental Science}, publisher={Frontiers Media SA}, author={Bouska, Kristen L. and Healy, Brian D. and Moore, Michael J. and Dunn, Corey G. and Spurgeon, Jonathan J. and Paukert, Craig P.}, year={2023}, month={Mar} }
 @article{besson_neary_stafford_dunn_miranda_2023, title={Fish functional gradients along a reservoir cascade}, volume={68}, url={http://dx.doi.org/10.1111/fwb.14087}, DOI={10.1111/fwb.14087}, abstractNote={Abstract


The transformations of fish assemblages caused by reservoir cascades can be severe at the reach scale, but basin‐scale effects are less clear. However, prevailing river concepts provide a framework for predicting basin‐scale effects.

To determine if predictions made by the River Continuum Concept relative to the function of fish assemblages are sustained in a temperate river transformed into a reservoir cascade, we examined longitudinal trends in the distribution of fish functional traits over 23 reservoirs of the Tennessee River, U.S.A.

In all, 115 species were recorded representing 62 traits, with trait richness increasing longitudinally in a downstream direction. Trophic, reproductive, and habitat traits showed various increasing and decreasing patterns up and down the reservoir cascade. The observed gradients in trait richness and trait distributions were generally consistent with those expected in unregulated rivers, with few unexpected results.

The transformation of lotic systems into lentic ones has changed habitats and sources of food and encouraged the proliferation of certain feeding (e.g., detritivores, planktivores, invertivores, piscivores), reproduction (e.g., nest spawners polyphils, broadcast spawners phytolithophils), and habitat (slow current, lacustrine, large river) traits. In essence, reservoirs have expanded downstream habitats in an upstream direction, and thus allowed upstream expansion of species and traits that would have normally not been well represented in upper reaches of the Tennessee River basin. Nevertheless, the impounded Tennessee River has maintained much of its functional integrity, despite extensive alterations to the riverscape.

We suggest that, while reservoirs have been shown to have major local‐scale effects on riverine fish assemblages, with access to riverine habitats, and with proactive conservation strategies, fish functional richness can remain remarkably high at the basin scale.

}, number={6}, journal={Freshwater Biology}, publisher={Wiley}, author={Besson, Jordan C. and Neary, Joshua J. and Stafford, Joshua D. and Dunn, Corey and Miranda, Leandro}, year={2023}, month={Jun}, pages={1079–1091} }
 @article{miranda_tompkins_dunn_morris_combs_2023, title={Patterns of zero and nonzero counts indicate spatiotemporal distributions, aggregation, and dispersion of invasive carp}, volume={14}, url={http://dx.doi.org/10.3391/mbi.2023.14.2.12}, DOI={10.3391/mbi.2023.14.2.12}, abstractNote={.}, number={2}, journal={Management of Biological Invasions}, publisher={Regional Euro-Asian Biological Invasions Centre Oy (REABIC)}, author={Miranda, Leandro and Tompkins, Joshua and Dunn, Corey and Morris, Jessica and Combs, Matthew}, year={2023}, pages={363–377} }
 @article{dunn_paukert_2021, title={Accounting for dispersal and local habitat when evaluating tributary use by riverine fishes}, volume={12}, url={http://dx.doi.org/10.1002/ecs2.3711}, DOI={10.1002/ecs2.3711}, abstractNote={AbstractConservation practitioners increasingly recognize the conservation value of tributaries for supporting mainstem, large‐river specialist fishes. A tributary’s discharge at its mouth is a coarse indicator of the richness of large‐river specialists found within the tributary, but the relative influences of regional dispersal and local habitat underpinning this species–discharge relationship are often unknown. We sampled large‐river specialist fishes at sites within two nonwadeable tributaries of the Missouri and Mississippi rivers with contrasting prairie (Grand River) vs. upland (Meramec River) habitats to address four research questions: (1) Do alpha diversity (mean site‐level species richness) and beta diversity (among‐site species compositional differences) vary between tributaries? (2) Does mean annual discharge correlate with local habitat and downstream distance to mainstem rivers (i.e., mainstem connectivity)? (3) Are slopes of species–discharge relationships consistent between tributaries? And (4) Do local habitat and downstream distance explain residual richness at sites beyond variation already explained by species–discharge relationships? We detected 30 of 42 potential large‐river specialist fishes, demonstrating most mainstem species use tributaries. Mean site richness was higher in the Grand River (12.5 species vs. 9.8 species in Meramec River), but partitioning of lower reaches (sites < 116 km from river mouth) and dispersal limitation in upper reaches (sites ≥ 145 km from river mouth) caused Meramec River beta diversity to be three times higher. Mean annual discharge correlated with habitat availability at sites and downstream distance to a mainstem. Although site‐level alpha richness generally increased with discharge in both tributaries, slopes of species–discharge relationships varied between tributaries. Analyzing species–discharge residuals revealed downstream distance explained additional variation in site‐level richness not accounted for by local discharge. For example, discharge alone underrepresented richness in lower‐discharge sites accessible to dispersers (maximum underestimate = 8.7 species) and overrepresented richness in isolated sites (maximum overestimate = 5.8 species). Thus, predictive performance of species–discharge relationships can be improved by accounting for varying habitats among tributaries and downstream distance of sites to mainstems when valuing tributaries for fishes with dispersal‐dependent life cycles.}, number={8}, journal={Ecosphere}, publisher={Wiley}, author={Dunn, Corey G. and Paukert, Craig P.}, year={2021}, month={Aug} }
 @article{dunn_moore_sievert_paukert_distefano_2021, title={Co-occurring lotic crayfishes exhibit variable long-term responses to extreme-flow events and temperature}, volume={11}, url={http://dx.doi.org/10.1086/717486}, DOI={10.1086/717486}, abstractNote={Crayfish serve critical roles in aquatic ecosystems as engineers, omnivores, and prey. It is unclear how increasingly frequent extreme-flow events and warming air temperatures will affect crayfish populations, partly because there are few long-term crayfish monitoring datasets. Using a unique 10-y dataset, we asked 1) whether recruitment of crayfishes in summer responded to extreme-flow events and air temperature during spring brooding and summer growing periods and 2) whether responses were similar among 3 co-occurring crayfish species. Golden (Faxonius luteus [Creaser, 1933]), Ozark (Faxonius ozarkae [Williams, 1952]), and Spothand (Faxonius punctimanus [Creaser, 1933]) crayfishes were sampled in quadrats at 2 sites each in the Big Piney (1993–2000) and Jacks Fork (1992–2001) rivers (Missouri, USA; n = 3355 1-m2 quadrats). We used zero-inflated generalized linear models to relate variability in quadrat-level age-0 counts to mean daily maximum air temperatures and flow metrics (variability, magnitude, and frequency of extreme high- and low-flow events). Species ranged from a small-bodied, abundant habitat generalist (Golden Crayfish) to large-bodied, uncommon habitat specialists (Ozark and Spothand crayfishes). Golden Crayfish occurred in higher-velocity habitats (riffles, runs) and had variable recruitment that increased during years with few spring and summer high-flow events and summers with lower flows and warmer temperatures. In contrast, annual recruitment variability of Ozark and Spothand crayfishes was low and explained by positive effects of cooler summers and by different flow metrics. Spothand Crayfish recruitment decreased in years with frequent spring and summer high-flow events, whereas lower summer minimum flow was the only flow metric that explained slight increases in Ozark Crayfish recruitment. Relationships with the preceding year’s recruitment were quadratic for Ozark and Spothand crayfishes, suggesting potential density dependence at higher recruitment levels. Species-specific responses suggest that closely related crayfishes could respond idiosyncratically to changes in temperature and flow. Temperature- and flow-related disturbances may be key mechanisms mediating competition and, thus, may help maintain crayfish diversity. However, warming air temperatures and increasingly frequent extreme-flow events could disadvantage some species, thereby altering future crayfish assemblages.}, journal={Freshwater Science}, publisher={University of Chicago Press}, author={Dunn, Corey G. and Moore, Michael J. and Sievert, Nicholas A. and Paukert, Craig P. and DiStefano, Robert J.}, year={2021}, month={Nov}, pages={000–000} }
 @article{dunn_paukert_2020, title={A flexible survey design for monitoring spatiotemporal fish richness in nonwadeable rivers: optimizing efficiency by integrating gears}, volume={77}, url={http://dx.doi.org/10.1139/cjfas-2019-0315}, DOI={10.1139/cjfas-2019-0315}, abstractNote={ We designed a flexible protocol for monitoring fish species richness in nonwadeable rivers. Nine sites were sampled seasonally with six gears in two physiographic regions in Missouri (USA). Using resampling procedures and mixed-effects modeling, we quantified richness and compositional overlap among gears, identified efficient gear combinations, and evaluated protocol performance across regions and seasons. We detected 25–75 species per sample and 89 185 fish. On average, no single gear detected >62% of observed species, but an optimized, integrated-gear protocol with four complementary gears on average detected 90% of species while only requiring 51.9% of initial sampling effort. Neither season nor physiographic region explained low spatiotemporal variation in percent richness detected by the integrated-gear protocol. In contrast, equivalent effort with an electrofishing-only protocol was 53.5% less efficient, seasonally biased and imprecise (36.1%–82.3% of richness), and on average detected 15.9% less of observed richness. Altogether, riverine fish richness is likely underestimated with single-gear survey designs. When paired with existing wadeable-stream inventories, our customizable approach could benefit regional monitoring by comprehensively documenting riverine contributions to riverscape biodiversity. }, number={6}, journal={Canadian Journal of Fisheries and Aquatic Sciences}, publisher={Canadian Science Publishing}, author={Dunn, Corey G. and Paukert, Craig P.}, year={2020}, month={Jun}, pages={978–990} }
 @article{dunn_brooke_hrabik_paukert_2018, title={Intensive Sampling Reveals Underreported Use of Great-River Tributaries by Large-River Fishes in Missouri}, volume={17}, url={http://dx.doi.org/10.1656/058.017.0316}, DOI={10.1656/058.017.0316}, abstractNote={Abstract Large tributaries may help sustain large-river fish populations by mitigating fish-habitat losses within the highly modified great rivers of the Mississippi River basin. These tributaries are likely most beneficial for fish species specializing on non-degraded large-river habitat for some portion of their life histories. Few great-river tributaries, however, have been surveyed using methods that comprehensively target all fish species, resulting in uncertainty or bias in the reported composition of many tributary fish assemblages. We report important distributional records, including 23 new accounts, for 12 large-river specialist fishes in Missouri—Alosa alabamae (Alabama Shad), Cycleptus elongatus (Blue Sucker), Pimephales vigilax (Bullhead Minnow), Notropis wickliffi (Channel Shiner), Polyodon spathula (Paddlefish), Hybognathus placitus (Plains Minnow), N. blennius (River Shiner), Macrhybopsis hyostoma (Shoal Chub), Scaphirhynchus platorynchus (Shovelnose Sturgeon), M. storeriana (Silver Chub), Ichthyomyzon unicuspis (Silver Lamprey), and Alosa chrysochloris (Skipjack Herring)—following 38 comprehensive fish surveys in tributaries of the Missouri and Mississippi rivers. New accounts collectively demonstrate tributaries support more large-river specialists than historically documented and thus may be currently undervalued sources of habitat for large-river fishes.}, number={3}, journal={Southeastern Naturalist}, author={Dunn, C.G. and Brooke, B.L. and Hrabik, R.A. and Paukert, C.P.}, year={2018}, month={Sep}, pages={512–520} }
 @article{dunn_angermeier_2019, title={Remaining populations of an upland stream fish persist in refugia defined by habitat features at multiple scales}, volume={25}, url={http://dx.doi.org/10.1111/ddi.12866}, DOI={10.1111/ddi.12866}, abstractNote={AbstractAimConserving stream biota could require strategies that preserve habitats conveying resistance to ecological impacts of changing land use and climate. Retrospective analyses of species’ responses to anthropogenic disturbances can inform such strategies. We developed a hierarchical framework to contrast environmental conditions underlying persistence versus extirpation of an imperilled stream fish, Candy Darter (Etheostoma osburni), over decades of changing land use. The decline of E. osburni may broadly represent the challenge of conserving sensitive freshwater species in intensively used upland environments.LocationNew River drainage, Appalachian Mountains, USA.MethodsWe surveyed fish and habitat in historically occupied sites to identify population refugia, and used multivariate and spatial analyses to address three questions: (a) what are the environmental correlates of refugia? (b) are the pathways by which land use impacts instream habitat constrained by catchment‐ and/or segment‐scale features? and (c) are E. osburni distributional dynamics spatially structured and explained by fine sediment and warm stream temperatures?ResultsWe confirmed a recently localized distribution similar to other upland species, marked by at least seven extirpations from streams throughout E. osburni's southern range. Catchment‐scale features primarily constrained land use and finer‐scale habitat, leading to either extirpations or population‐supporting refugia defined by features at multiple scales. Refugium habitats contained cooler temperatures and less fine sediment. Rare mismatches between persistence and habitat suitability were explained by network location, suggesting unmeasured environmental gradients and/or dispersal contributed to distributional dynamics.Main conclusionsWe provided insight at multiple spatial scales into how aquatic species’ distributions become fragmented and localized. Our results demonstrate that natural landscape heterogeneity imparts spatially variable resistance of sensitive species to intensive land uses. By recognizing the scale‐specific features that buffer populations from extirpation, conservation strategies could be tailored to protect naturally occurring refugium habitats and focus restoration in systems where such habitats are broadly lacking.}, number={3}, journal={Diversity and Distributions}, author={Dunn, C.G. and Angermeier, P.L.}, year={2019}, month={Mar}, pages={385–399} }
 @article{dunn_angermeier_2016, title={Development of Habitat Suitability Indices for the Candy Darter, with Cross-Scale Validation across Representative Populations}, volume={145}, url={http://dx.doi.org/10.1080/00028487.2016.1217929}, DOI={10.1080/00028487.2016.1217929}, abstractNote={AbstractUnderstanding relationships between habitat associations for individuals and habitat factors that limit populations is a primary challenge for managers of stream fishes. Although habitat use by individuals can provide insight into the adaptive significance of selected microhabitats, not all habitat parameters will be significant at the population level, particularly when distributional patterns partially result from habitat degradation. We used underwater observation to quantify microhabitat selection by an imperiled stream fish, the Candy Darter Etheostoma osburni, in two streams with robust populations. We developed multiple‐variable and multiple‐life‐stage habitat suitability indices (HSIs) from microhabitat selection patterns and used them to assess the suitability of available habitat in streams where Candy Darter populations were extirpated, localized, or robust. Next, we used a comparative framework to examine relationships among (1) habitat availability across streams, (2) projected habitat suitability of each stream, and (3) a rank for the likely long‐term viability (robustness) of the population inhabiting each stream. Habitat selection was characterized by ontogenetic shifts from the low‐velocity, slightly embedded areas used by age‐0 Candy Darters to the swift, shallow areas with little fine sediment and complex substrate, which were used by adults. Overall, HSIs were strongly correlated with population rank. However, we observed weak or inverse relationships between predicted individual habitat suitability and population robustness for multiple life stages and variables. The results demonstrated that microhabitat selection by individuals does not always reflect population robustness, particularly when based on a single life stage or season, which highlights the risk of generalizing habitat selection that is observed during nonstressful periods or for noncritical resources. These findings suggest that stream fish managers may need to be cautious when implementing conservation measures based solely on observations of habitat selection by individuals and that detailed study at the individual and population levels may be necessary to identify habitat that limits populations.Received March 30, 2016; accepted July 19, 2016Published online October 7, 2016}, number={6}, journal={Transactions of the American Fisheries Society}, author={Dunn, C.G. and Angermeier, P.L.}, year={2016}, month={Nov}, pages={1266–1281} }
 @article{dunn_2016, title={Documentation of Cryptobranchus alleganiensis alleganiensis (Eastern Hellbender) Predation on Nest-Associate Stream Fishes}, volume={23}, url={http://dx.doi.org/10.1656/045.023.0303}, DOI={10.1656/045.023.0303}, abstractNote={Abstract 
 The covert habits of Cryptobranchus alleganiensis alleganiensis (Eastern Hellbender) make direct field observations of their behavior difficult. Here I provide the first video documentation of in situ predation by a hellbender on a spawning aggregation of stream fishes. Both targeting fish and diurnal activity are behaviors rarely documented among hellbenders. The present observation, however, supports previously described patterns of elevated diurnal activity in late spring hypothesized to be associated with increased foraging-activity to meet higher energy-demands. The observation demonstrates that Eastern Hellbenders will modify behavior to exploit stream fishes when prey are easily captured.}, number={3}, journal={Northeastern Naturalist}, author={Dunn, C.G.}, year={2016}, month={Sep} }