@article{anderson_valera_schnetzer_2023, title={Co-occurrence of freshwater and marine phycotoxins: A record of microcystins and domoic acid in Bogue Sound, North Carolina (2015 to 2020)}, volume={125}, ISSN={["1878-1470"]}, url={https://doi.org/10.1016/j.hal.2023.102412}, DOI={10.1016/j.hal.2023.102412}, abstractNote={Harmful algal blooms (HABs) create issues both environmentally and economically in coastal regions, especially if algal growth is linked to the production of toxins which can affect ecosystems, wildlife, and humans. This study is the first to confirm near year-round presence and co-occurrence of microcystins (MCs) and domoic acid (DA) within the outskirts of the largest lagoonal US estuary, the Pamlico-Albemarle Sound System (PASS). Monthly sampling at a time-series location in Bogue Sound, located within the eastern part of the PASS, showed DA and MCs were commonly present and detected together 50% of the time based on an in situ toxin tracking approach over a 6-year time period (2015-2020). Particulate toxin concentrations based on monthly grab sampling remained well below regulatory thresholds for MCs and below DA concentrations associated with animal sickness and mortality elsewhere. Time-integrated levels for dissolved MCs and DA, however, indicated a continuous presence of both toxins within Bogue Sound where high flushing rates (∼2-day average residence time) presumably alleviate potential issues linked to nutrient inputs, subsequent algal growth, or toxin accumulation. Pseudo-nitzschia spp. contributed 0 to 19% to the resident microplankton community. Light microscopy analyses did not reveal the source of MCs production in the sound but suggested potential downstream transport and/or autochthonous production due to taxa not accounted for in this study (e.g., picocyanobacteria). Nitrate+nitrite (NOx) concentrations, wind speed, and water temperature explained a third of the variations in accumulated dissolved MCs, but no relationship was seen for DA concentrations based on monthly sampling within this highly dynamic system. This study emphasizes the importance of continued algal toxin monitoring in systems like Bogue Sound which might experience decreases in water quality similar to adjacent, nutrient-impaired regions within the PASS.}, journal={HARMFUL ALGAE}, author={Anderson, Madeline and Valera, Marco and Schnetzer, Astrid}, year={2023}, month={Jun} }
 @article{pierce_torano_lin_schnetzer_marchetti_2023, title={Comparison of advanced methodologies for diatom identification within dynamic coastal communities}, volume={9}, ISSN={["1541-5856"]}, DOI={10.1002/lom3.10575}, abstractNote={Abstract}, journal={LIMNOLOGY AND OCEANOGRAPHY-METHODS}, author={Pierce, Emily and Torano, Olivia and Lin, Yuanyu and Schnetzer, Astrid and Marchetti, Adrian}, year={2023}, month={Sep} }
 @article{pierce_schnetzer_2023, title={Microcystin Concentrations, Partitioning, and Structural Composition during Active Growth and Decline: A Laboratory Study}, volume={15}, ISSN={["2072-6651"]}, url={https://doi.org/10.3390/toxins15120684}, DOI={10.3390/toxins15120684}, abstractNote={Microcystin can be present in variable concentrations, phases (dissolved and particulate), and structural forms (congeners), all which impact the toxicity and persistence of the algal metabolite. Conducting incubation experiments with six bloom assemblages collected from the Chowan River, North Carolina, we assessed microcystin dynamics during active growth and biomass degradation. Upon collection, average particulate and dissolved microcystin ranged between 0.2 and 993 µg L−1 and 0.5 and 3.6 µg L−1, respectively. The presence of congeners MC-LA, -LR, -RR, and -YR was confirmed with MC-RR and MC-LR being the most prevalent. Congener composition shifted over time and varied between dissolved and particulate phases. Particulate microcystin exponentially declined in five of six incubations with an average half-life of 10.2 ± 3.7 days, while dissolved microcystin remained detectable until the end of the incubation trials (up to 100 days). Our findings suggest that concerns about food-web transfer via intracellular toxins seem most warranted within the first few weeks of the bloom peak, while dissolved toxins linger for several months in the aftermath of the event. Also, it was indicated there were differences in congener profiles linked to the sampling method. We believe this study can inform monitoring strategies and aid microcystin-exposure risk assessments for cyanobacterial blooms.}, number={12}, journal={TOXINS}, author={Pierce, Emily F. and Schnetzer, Astrid}, year={2023}, month={Dec} }
 @article{kirkwood-donelson_dodds_schnetzer_hall_baker_2023, title={Uncovering per- and polyfluoroalkyl substances (PFAS) with nontargeted ion mobility spectrometry–mass spectrometry analyses}, url={https://doi.org/10.1126/sciadv.adj7048}, DOI={10.1126/sciadv.adj7048}, abstractNote={Because of environmental and health concerns, legacy per- and polyfluoroalkyl substances (PFAS) have been voluntarily phased out, and thousands of emerging PFAS introduced as replacements. Traditional analytical methods target a limited number of mainly legacy PFAS; therefore, many species are not routinely assessed in the environment. Nontargeted approaches using high-resolution mass spectrometry methods have therefore been used to detect and characterize unknown PFAS. However, their ability to elucidate chemical structures relies on generation of informative fragments, and many low concentration species are not fragmented in typical data-dependent acquisition approaches. Here, a data-independent method leveraging ion mobility spectrometry (IMS) and size-dependent fragmentation was developed and applied to characterize aquatic passive samplers deployed near a North Carolina fluorochemical manufacturer. From the study, 11 PFAS structures for various per- and polyfluorinated ether sulfonic acids and multiheaded perfluorinated ether acids were elucidated in addition to 36 known PFAS. Eight of these species were previously unreported in environmental media, and three suspected species were validated.}, journal={Science Advances}, author={Kirkwood-Donelson, Kaylie I. and Dodds, James N. and Schnetzer, Astrid and Hall, Nathan and Baker, Erin S.}, year={2023}, month={Oct} }
 @article{patrick_kominoski_mcdowell_branoff_lagomasino_leon_hensel_hensel_strickland_aide_et al._2022, title={A general pattern of trade-offs between ecosystem resistance and resilience to tropical cyclones}, volume={8}, ISSN={["2375-2548"]}, DOI={10.1126/sciadv.abl9155}, abstractNote={
            Tropical cyclones drive coastal ecosystem dynamics, and their frequency, intensity, and spatial distribution are predicted to shift with climate change. Patterns of resistance and resilience were synthesized for 4138 ecosystem time series from
            n
            = 26 storms occurring between 1985 and 2018 in the Northern Hemisphere to predict how coastal ecosystems will respond to future disturbance regimes. Data were grouped by ecosystems (fresh water, salt water, terrestrial, and wetland) and response categories (biogeochemistry, hydrography, mobile biota, sedentary fauna, and vascular plants). We observed a repeated pattern of trade-offs between resistance and resilience across analyses. These patterns are likely the outcomes of evolutionary adaptation, they conform to disturbance theories, and they indicate that consistent rules may govern ecosystem susceptibility to tropical cyclones.
          }, number={9}, journal={SCIENCE ADVANCES}, author={Patrick, Christopher J. and Kominoski, John S. and McDowell, William H. and Branoff, Benjamin and Lagomasino, David and Leon, Miguel and Hensel, Enie and Hensel, Marc J. S. and Strickland, Bradley A. and Aide, T. Mitchell and et al.}, year={2022}, month={Mar} }
 @article{corradino_schnetzer_2022, title={Grazing of a heterotrophic nanoflagellate on prokaryote and eukaryote prey: ingestion rates and gross growth efficiency}, volume={682}, ISSN={["1616-1599"]}, DOI={10.3354/meps13921}, abstractNote={Heterotrophic nanoflagellates (HNANs) play a pivotal role as consumers of picoplankton, remineralizers and carbon vectors, yet knowledge on how prey quantity and quality affect HNAN physiology remains limited. In a series of grazing experiments using an uncharacterized member of the HNAN assemblage, we found that growth (μ) and ingestion rate (IR) varied when offering heterotrophic bacteria (HB), Synechococcus spp. (Syn), Ostreococcus lucimarinus (Ost) or a combination of all 3 prey types. Highest average μ rates (1.8 d-1) were detected on HB at densities of ~106 cells ml-1 and maximum IR on Syn (485 pg C d-1) at ~106 cells ml-1. Independent of prey type, flagellate μ increased with IR up to ~50 pg C d-1. A relatively low P-content in Ost was linked to shifts in C:N:P ratios of the HNAN in the single-prey experiment and when Ost was offered as part of the mixed assemblage. Presented with a mixed diet, the highest contribution to daily C intake came from Ost with 50%, followed by HB with 46% and Syn with only 4%. C-based gross growth efficiencies (GGEs) were higher when feeding on HB and mixed prey, compared to both picophototrophs, while N- and P-based GGEs in mixed prey treatments markedly exceeded those when feeding on any single prey. The findings in this study corroborate the importance of investigating the biogeochemical role of HNANs in relation to prey availability and quality to refine estimates of energy transfer within the microbial loop.}, journal={MARINE ECOLOGY PROGRESS SERIES}, author={Corradino, Gabrielle L. and Schnetzer, Astrid}, year={2022}, month={Jan}, pages={65–77} }
 @misc{hall_wickes_burnett_scott_hernandez_yates_barbero_reimer_baalousha_mintz_et al._2020, title={Acidification in the US Southeast: Causes, Potential Consequences and the Role of the Southeast Ocean and Coastal Acidification Network}, volume={7}, ISSN={["2296-7745"]}, url={http://dx.doi.org/10.3389/fmars.2020.00548}, DOI={10.3389/fmars.2020.00548}, abstractNote={Coastal acidification in southeastern U.S. estuaries and coastal waters is influenced by biological activity, run-off from the land, and increasing carbon dioxide in the atmosphere. Acidification can negatively impact coastal resources such as shellfish, finfish, and coral reefs, and the communities that rely on them. Organismal responses for species located in the U.S. Southeast document large negative impacts of acidification, especially in larval stages. For example, the toxicity of pesticides increases under acidified conditions and the combination of acidification and low oxygen has profoundly negative influences on genes regulating oxygen consumption. In corals, the rate of calcification decreases with acidification and processes such as wound recovery, reproduction, and recruitment are negatively impacted. Minimizing the changes in global ocean chemistry will ultimately depend on the reduction of carbon dioxide emissions, but adaptation to these changes and mitigation of the local stressors that exacerbate global acidification can be addressed locally. The evolution of our knowledge of acidification, from basic understanding of the problem to the emergence of applied research and monitoring, has been facilitated by the development of regional Coastal Acidification Networks (CANs) across the United States. This synthesis is a product of the Southeast Coastal and Ocean Acidification Network (SOCAN). SOCAN was established to better understand acidification in the coastal waters of the U.S. Southeast and to foster communication among scientists, resource managers, businesses, and governments in the region. Here we review acidification issues in the U.S. Southeast, including the regional mechanisms of acidification and their potential impacts on biological resources and coastal communities. We recommend research and monitoring priorities and discuss the role SOCAN has in advancing acidification research and mitigation of and adaptation to these changes.}, journal={FRONTIERS IN MARINE SCIENCE}, publisher={Frontiers Media SA}, author={Hall, Emily R. and Wickes, Leslie and Burnett, Louis E. and Scott, Geoffrey I and Hernandez, Debra and Yates, Kimberly K. and Barbero, Leticia and Reimer, Janet J. and Baalousha, Mohammed and Mintz, Jennifer and et al.}, year={2020}, month={Jul} }
 @book{southeast atlantic and gulf of mexico region ocean acidification research_2020, journal={NOAA Ocean and Great Lakes Acidification Research Plan 2020-2029}, year={2020}, month={Jul} }
 @article{shields_bianchi_osburn_kinsey_ziervogel_schnetzer_corradino_2019, title={Linking chromophoric organic matter transformation with biomarker indices in a marine phytoplankton growth and degradation experiment}, volume={214}, ISSN={["1872-7581"]}, DOI={10.1016/j.marchem.2019.103665}, abstractNote={The production and transformation of marine chromophoric dissolved organic matter (CDOM) provides a window into the marine biological pump as it is present at all depths and can be measured both in the field and via satellite. However, outside of lignin for terrestrial DOM, few studies have linked marine CDOM characteristics with biomarker indices. In this study, we quantified five fluorescent components of marine CDOM and base-extractable particulate organic matter (BEPOM) in a growth and degradation experiment using a natural plankton assemblage, and compared those results to bacterial abundances, hydrolytic enzyme activities, and amino acid concentrations and associated diagenetic indices. Rotating glass bottles containing plankton were sampled initially (day 0), during the mid-exponential (day 13) and stationary (day 20) growth phases, and again following a dark degradation period that lasted 42 days. Protein-like fluorescence (tryptophan-like and tyrosine-like) was correlated with the total amino acid concentrations for both the DOM and BEPOM through all phases of the incubation. However, tryptophan-like fluorescence showed a stronger correlation for aromatic amino acids. The concentration of particulate organic carbon changed significantly during each phase of the experiment and this substrate correlated with hydrolytic enzyme activities and bacterial abundance. This heterotrophy diagenetically altered the POM during the stationary phase and ultimately resulted in the increased production of more humic-like CDOM after degradation in the dark. Results from this study indicate that CDOM formation and cycling may play a prominent role in the ocean's nitrogen cycle.}, journal={MARINE CHEMISTRY}, author={Shields, Michael R. and Bianchi, Thomas S. and Osburn, Christopher L. and Kinsey, Joanna D. and Ziervogel, Kai and Schnetzer, Astrid and Corradino, Gabrielle}, year={2019}, month={Aug} }
 @article{smith_connell_evans_gellene_howard_jones_kaveggia_palmer_schnetzer_seegers_et al._2018, title={A decade and a half of Pseudo-nitzschia spp. and domoic acid along the coast of southern California}, volume={79}, ISSN={["1878-1470"]}, DOI={10.1016/j.hal.2018.07.007}, abstractNote={Blooms of the marine diatom genus Pseudo-nitzschia that produce the neurotoxin domoic acid have been documented with regularity along the coast of southern California since 2003, with the occurrence of the toxin in shellfish tissue predating information on domoic acid in the particulate fraction in this region. Domoic acid concentrations in the phytoplankton inhabiting waters off southern California during 2003, 2006, 2007, 2011 and 2017 were comparable to some of the highest values that have been recorded in the literature. Blooms of Pseudo-nitzschia have exhibited strong seasonality, with toxin appearing predominantly in the spring. Year-to-year variability of particulate toxin has been considerable, and observations during 2003, 2006, 2007, 2011 and again in 2017 linked domoic acid in the diets of marine mammals and seabirds to mass mortality events among these animals. This work reviews information collected during the past 15 years documenting the phenology and magnitude of Pseudo-nitzschia abundances and domoic acid within the Southern California Bight. The general oceanographic factors leading to blooms of Pseudo-nitzschia and outbreaks of domoic acid in this region are clear, but subtle factors controlling spatial and interannual variability in bloom magnitude and toxin production remain elusive.}, journal={HARMFUL ALGAE}, author={Smith, Jayme and Connell, Paige and Evans, Richard H. and Gellene, Alyssa G. and Howard, Meredith D. A. and Jones, Burton H. and Kaveggia, Susan and Palmer, Lauren and Schnetzer, Astrid and Seegers, Bridget N. and et al.}, year={2018}, month={Nov}, pages={87–104} }
 @misc{wiltsie_schnetzer_green_vander borgh_fensin_2018, title={Algal Blooms and Cyanotoxins in Jordan Lake, North Carolina}, volume={10}, ISSN={["2072-6651"]}, DOI={10.3390/toxins10020092}, abstractNote={The eutrophication of waterways has led to a rise in cyanobacterial, harmful algal blooms (CyanoHABs) worldwide. The deterioration of water quality due to excess algal biomass in lakes has been well documented (e.g., water clarity, hypoxic conditions), but health risks associated with cyanotoxins remain largely unexplored in the absence of toxin information. This study is the first to document the presence of dissolved microcystin, anatoxin-a, cylindrospermopsin, and β-N-methylamino-l-alanine in Jordan Lake, a major drinking water reservoir in North Carolina. Saxitoxin presence was not confirmed. Multiple toxins were detected at 86% of the tested sites and during 44% of the sampling events between 2014 and 2016. Although concentrations were low, continued exposure of organisms to multiple toxins raises some concerns. A combination of discrete sampling and in-situ tracking (Solid Phase Adsorption Toxin Tracking [SPATT]) revealed that microcystin and anatoxin were the most pervasive year-round. Between 2011 and 2016, summer and fall blooms were dominated by the same cyanobacterial genera, all of which are suggested producers of single or multiple cyanotoxins. The study’s findings provide further evidence of the ubiquitous nature of cyanotoxins, and the challenges involved in linking CyanoHAB dynamics to specific environmental forcing factors are discussed.}, number={2}, journal={TOXINS}, author={Wiltsie, Daniel and Schnetzer, Astrid and Green, Jason and Vander Borgh, Mark and Fensin, Elizabeth}, year={2018}, month={Feb} }
 @article{kinsey_corradino_ziervogel_schnetzer_osburn_2018, title={Formation of Chromophoric Dissolved Organic Matter by Bacterial Degradation of Phytoplankton-Derived Aggregates}, volume={4}, ISSN={2296-7745}, url={http://dx.doi.org/10.3389/fmars.2017.00430}, DOI={10.3389/fmars.2017.00430}, abstractNote={Organic matter produced and released by phytoplankton during growth is processed by heterotrophic bacterial communities that transform dissolved organic matter into biomass and recycle inorganic nutrients, fueling microbial food web interactions. Bacterial transformation of phytoplankton-derived organic matter also plays a poorly known role in the formation of chromophoric dissolved organic matter (CDOM) which is ubiquitous in the ocean. Despite the importance of organic matter cycling, growth of phytoplankton and activities of heterotrophic bacterial communities are rarely measured in concert. To investigate CDOM formation mediated by microbial processing of phytoplankton-derived aggregates, we conducted growth experiments with non-axenic monocultures of three diatoms (Skeletonema grethae, Leptocylindrus hargravesii, Coscinodiscus sp.) and one haptophyte (Phaeocystis globosa). Phytoplankton biomass, carbon concentrations, CDOM and base-extracted particulate organic matter (BEPOM) fluorescence, along with bacterial abundance and hydrolytic enzyme activities (α-glucosidase, β-glucosidase, leucine-aminopeptidase) were measured during exponential growth and stationary phase (~3-6 weeks) and following six weeks of POM degradation. Incubations were performed in rotating glass bottles to keep cells suspended, promoting cell coagulation and, thus, formation of macroscopic aggregates (marine snow), more similar to surface ocean processes. Maximum carbon concentrations, enzyme activities, and BEPOM fluorescence occurred during stationary phase. Net DOC concentrations (0.19-0.46 mg C L-1) increased on the same order as open ocean concentrations. CDOM fluorescence was dominated by protein-like signals that increased throughout growth and degradation becoming increasingly humic-like, implying the production of more complex molecules from planktonic-precursors mediated by microbial processing. Our experimental results suggest that at least a portion of open-ocean CDOM is produced by autochthonous processes and aggregation likely facilitates microbial reprocessing of organic matter into refractory DOM.}, journal={Frontiers in Marine Science}, publisher={Frontiers Media SA}, author={Kinsey, Joanna D. and Corradino, Gabrielle and Ziervogel, Kai and Schnetzer, Astrid and Osburn, Christopher L.}, year={2018}, month={Jan} }
 @article{tatters_schnetzer_xu_walworth_fu_spackeen_sipler_bertrand_mcquaid_allen_et al._2018, title={Interactive effects of temperature, CO2 and nitrogen source on a coastal California diatom assemblage}, volume={40}, ISSN={["1464-3774"]}, DOI={10.1093/plankt/fbx074}, abstractNote={We investigated the response of a natural diatom-dominated assemblage in coastal California to interactions between the variables nitrogen (nitrate and (19 and 23 and CO 2 (380 and 800 ppm) in a factorial experimental matrix using continuous culture (ecostat) methods. The community included diatoms of the cosmopolitan genera Pseudo-nitzschia and Chaetoceros as well as Leptocylindrus and Cylindrotheca . Our results demonstrate strong interactive effects of these variables on community composition; notably, nitrogen source alone and nitrogen and CO 2 together had a much greater in fl uence on diatom community structure at 23 ° C compared with 19 ° C. In addition, warming and acidi fi cation interactions signi fi cantly increased cellular quotas of the neurotoxin domoic acid produced by Pseudo-nitzschia multiseries . In general, the effects observed for the factors tested dif-fered signi fi cantly between the various diatom genera in this assemblage, suggesting potentially divergent responses of some of these ecologically and biogeochemically important phytoplankton taxa to interactions between global-scale and local-scale anthropogenic stressors in a changing ocean.}, number={2}, journal={JOURNAL OF PLANKTON RESEARCH}, author={Tatters, Avery O. and Schnetzer, Astrid and Xu, Kai and Walworth, Nathan G. and Fu, Feixue and Spackeen, Jenna L. and Sipler, Rachel E. and Bertrand, Erin M. and Mcquaid, Jeffrey B. and Allen, Andrew E. and et al.}, year={2018}, pages={151–164} }
 @article{schnetzer_lampe_benitez-nelson_marchetti_osburn_tatters_2017, title={Marine snow formation by the toxin-producing diatom, Pseudo-nitzschia australis}, volume={61}, ISSN={["1878-1470"]}, DOI={10.1016/j.hal.2016.11.008}, abstractNote={The formation of marine snow (MS) by the toxic diatom Pseudo-nitschia australis was simulated using a roller table experiment. Concentrations of particulate and dissolved domoic acid (pDA and dDA) differed significantly among exponential phase and MS formation under simulated near surface conditions (16 °C/12:12-dark:light cycle) and also differed compared to subsequent particle decomposition at 4 °C in the dark, mimicking conditions in deeper waters. Particulate DA was first detected at the onset of exponential growth, reached maximum levels associated with MS aggregates (1.21 ± 0.24 ng mL−1) and declined at an average loss rate of ∼1.2% pDA day−1 during particle decomposition. Dissolved DA concentrations increased throughout the experiment and reached a maximum of ∼20 ng mL−1 at final sampling on day 88. The succession by P. australis from active growth to aggregation resulted in increasing MS toxicity and based on DA loading of particles and known in situ sinking speeds, a significant amount of toxin could have easily reached the deeper ocean or seafloor. MS formation was further associated with significant dDA accumulation at a ratio of pDA: dDA: cumulative dDA of approximately 1:10:100. Overall, this study confirms that MS functions as a major vector for toxin flux to depth, that Pseudo-nitzschia-derived aggregates should be considered ‘toxic snow’ for MS-associated organisms, and that effects of MS toxicity on interactions with aggregate-associated microbes and zooplankton consumers warrant further consideration.}, journal={HARMFUL ALGAE}, author={Schnetzer, Astrid and Lampe, Robert H. and Benitez-Nelson, Claudia R. and Marchetti, Adrian and Osburn, Christopher L. and Tatters, Avery O.}, year={2017}, month={Jan}, pages={23–30} }
 @article{caron_connell_schaffner_schnetzer_fuhrman_countway_kim_2017, title={Planktonic food web structure at a coastal time-series site: I. Partitioning of microbial abundances and carbon biomass}, volume={121}, ISSN={["1879-0119"]}, DOI={10.1016/j.dsr.2016.12.013}, abstractNote={Biogeochemistry in marine plankton communities is strongly influenced by the activities of microbial species. Understanding the composition and dynamics of these assemblages is essential for modeling emergent community-level processes, yet few studies have examined all of the biological assemblages present in the plankton, and benchmark data of this sort from time-series studies are rare. Abundance and biomass of the entire microbial assemblage and mesozooplankton (>200 µm) were determined vertically, monthly and seasonally over a 3-year period at a coastal time-series station in the San Pedro Basin off the southwestern coast of the USA. All compartments of the planktonic community were enumerated (viruses in the femtoplankton size range [0.02–0.2 µm], bacteria + archaea and cyanobacteria in the picoplankton size range [0.2–2.0 µm], phototrophic and heterotrophic protists in the nanoplanktonic [2–20 µm] and microplanktonic [20–200 µm] size ranges, and mesozooplankton [>200 µm]. Carbon biomass of each category was estimated using standard conversion factors. Plankton abundances varied over seven orders of magnitude across all categories, and total carbon biomass averaged approximately 60 µg C l −1 in surface waters of the 890 m water column over the study period. Bacteria + archaea comprised the single largest component of biomass (>1/3 of the total), with the sum of phototrophic protistan biomass making up a similar proportion. Temporal variability at this subtropical station was not dramatic. Monthly depth-specific and depth-integrated biomass varied 2-fold at the station, while seasonal variances were generally <50%. This study provides benchmark information for investigating long-term environmental forcing on the composition and dynamics of the microbes that dominate food web structure and function at this coastal observatory. • Total plankton (viruses to mesozooplankton) was measured of southern California.. • Overall, plankton abundances varied by seven orders of magnitude. • Bacterial biomass averaged was nearly 40% of total biomass but mesozooplankton contributed ≤4%. • Seasonal changes in biomass were modest (<50%), depth-integrated values varied 2-fold.}, journal={DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS}, author={Caron, David A. and Connell, Paige E. and Schaffner, Rebecca A. and Schnetzer, Astrid and Fuhrman, Jed A. and Countway, Peter D. and Kim, Diane Y.}, year={2017}, month={Mar}, pages={14–29} }
 @article{andersson_kline_edmunds_archer_bednarsek_carpenter_chadsey_goldstein_grottoli_hurst_et al._2015, title={Understanding ocean acidification impacts on organismal to ecological scales}, volume={28}, DOI={10.5670/oceanog.2015.27}, abstractNote={Ocean acidification (OA) research seeks to understand how marine ecosystems and global elemental cycles will respond to changes in seawater carbonate chemistry in combination with other environmental perturbations such as warming, eutrophication, and deoxygenation. Here, we discuss the effectiveness and limitations of current research approaches used to address this goal. A diverse combination of approaches is essential to decipher the consequences of OA to marine organisms, communities, and ecosystems. Consequently, the benefits and limitations of each approach must be considered carefully. Major research challenges involve experimentally addressing the effects of OA in the context of large natural variability in seawater carbonate system parameters and other interactive variables, integrating the results from different research approaches, and scaling results across different temporal and spatial scales.}, number={2}, journal={Oceanography}, author={Andersson, A. J. and Kline, D. I. and Edmunds, P. J. and Archer, S. D. and Bednarsek, N. and Carpenter, R. C. and Chadsey, M. and Goldstein, P. and Grottoli, A. G. and Hurst, T. P. and et al.}, year={2015}, pages={16–27} }
 @article{kim_countway_jones_schnetzer_yamashita_tung_caron_2014, title={Monthly to interannual variability of microbial eukaryote assemblages at four depths in the eastern North Pacific}, volume={8}, ISSN={["1751-7370"]}, DOI={10.1038/ismej.2013.173}, abstractNote={Abstract}, number={3}, journal={ISME JOURNAL}, author={Kim, Diane Y. and Countway, Peter D. and Jones, Adriane C. and Schnetzer, Astrid and Yamashita, Warren and Tung, Christine and Caron, David A.}, year={2014}, month={Mar}, pages={515–530} }
 @article{schnetzer_jones_schaffner_cetinic_fitzpatrick_miller_seubert_caron_2013, title={Coastal upwelling linked to toxic Pseudo-nitzschia australis blooms in Los Angeles coastal waters, 20052007}, volume={35}, ISSN={["1464-3774"]}, DOI={10.1093/plankt/fbt051}, abstractNote={Harmful algal blooms dominated by the diatom Pseudo-nitzschia spp. have become a perennial but variable event within surface waters near the greater Los Angeles area. Toxic blooms during spring seasons from 2005 to 2007 varied strongly in their overall toxicity and duration. Differences in bloom dynamics were linked to differences in storm-induced river discharge following episodic rain events and coastal upwelling, both major coastal processes that led to the injection of nutrients into coastal surface waters. Heavy river runoff during early 2005, a record-rainfall year, favored a phytoplankton community mainly comprised of algal taxa other than Pseudo-nitzschia. The spring bloom during 2005 was associated with low domoic acid surface concentrations and minor contributions of (mainly) P. delicatissima to the diatom assemblage. In contrast, highly toxic P. australis-dominated blooms during spring seasons of 2006 and 2007 were linked to strong upwelling events. River discharge quotas in 2006 and 2007, in contrast to 2005, fell well below annual averages for the region. Surface toxin levels were linked to colder, more saline (i.e. upwelled) water over the 3-year study, but no such consistent relationship between domoic acid levels and other physiochemical parameters, such as macronutrient concentrations or nutrient ratios, was observed.}, number={5}, journal={JOURNAL OF PLANKTON RESEARCH}, author={Schnetzer, Astrid and Jones, Burton H. and Schaffner, Rebecca A. and Cetinic, Ivona and Fitzpatrick, Elizabeth and Miller, Peter E. and Seubert, Erica L. and Caron, David A.}, year={2013}, pages={1080–1092} }
 @article{tatters_schnetzer_fu_lie_caron_hutchins_2013, title={SHORT- VERSUS LONG-TERM RESPONSES TO CHANGING CO2 IN A COASTAL DINOFLAGELLATE BLOOM: IMPLICATIONS FOR INTERSPECIFIC COMPETITIVE INTERACTIONS AND COMMUNITY STRUCTURE}, volume={67}, ISSN={["1558-5646"]}, DOI={10.1111/evo.12029}, abstractNote={Increasing pCO2 (partial pressure of CO2) in an “acidified” ocean will affect phytoplankton community structure, but manipulation experiments with assemblages briefly acclimated to simulated future conditions may not accurately predict the long‐term evolutionary shifts that could affect inter‐specific competitive success. We assessed community structure changes in a natural mixed dinoflagellate bloom incubated at three pCO2 levels (230, 433, and 765 ppm) in a short‐term experiment (2 weeks). The four dominant species were then isolated from each treatment into clonal cultures, and maintained at all three pCO2 levels for approximately 1 year. Periodically (4, 8, and 12 months), these pCO2‐conditioned clones were recombined into artificial communities, and allowed to compete at their conditioning pCO2 level or at higher and lower levels. The dominant species in these artificial communities of CO2‐conditioned clones differed from those in the original short‐term experiment, but individual species relative abundance trends across pCO2 treatments were often similar. Specific growth rates showed no strong evidence for fitness increases attributable to conditioning pCO2 level. Although pCO2 significantly structured our experimental communities, conditioning time and biotic interactions like mixotrophy also had major roles in determining competitive outcomes. New methods of carrying out extended mixed species experiments are needed to accurately predict future long‐term phytoplankton community responses to changing pCO2.}, number={7}, journal={EVOLUTION}, author={Tatters, Avery O. and Schnetzer, Astrid and Fu, Feixue and Lie, Alle Y. A. and Caron, David A. and Hutchins, David A.}, year={2013}, month={Jul}, pages={1879–1891} }
 @article{tatters_roleda_schnetzer_fu_hurd_boyd_caron_lie_hoffmann_hutchins_2013, title={Short- and long-term conditioning of a temperate marine diatom community to acidification and warming}, volume={368}, url={http://dx.doi.org/10.1098/rstb.2012.0437}, DOI={10.1098/rstb.2012.0437}, abstractNote={
            Ocean acidification and greenhouse warming will interactively influence competitive success of key phytoplankton groups such as diatoms, but how long-term responses to global change will affect community structure is unknown. We incubated a mixed natural diatom community from coastal New Zealand waters in a short-term (two-week) incubation experiment using a factorial matrix of warming and/or elevated
            p
            CO
            2
            and measured effects on community structure. We then isolated the dominant diatoms in clonal cultures and conditioned them for 1 year under the same temperature and
            p
            CO
            2
            conditions from which they were isolated, in order to allow for extended selection or acclimation by these abiotic environmental change factors in the absence of interspecific interactions. These conditioned isolates were then recombined into ‘artificial’ communities modelled after the original natural assemblage and allowed to compete under conditions identical to those in the short-term natural community experiment. In general, the resulting structure of both the unconditioned natural community and conditioned ‘artificial’ community experiments was similar, despite differences such as the loss of two species in the latter.
            p
            CO
            2
            and temperature had both individual and interactive effects on community structure, but temperature was more influential, as warming significantly reduced species richness. In this case, our short-term manipulative experiment with a mixed natural assemblage spanning weeks served as a reasonable proxy to predict the effects of global change forcing on diatom community structure after the component species were conditioned in isolation over an extended timescale. Future studies will be required to assess whether or not this is also the case for other types of algal communities from other marine regimes.
          }, number={1627}, journal={Philosophical Transactions of the Royal Society B: Biological Sciences}, publisher={The Royal Society}, author={Tatters, Avery O. and Roleda, Michael Y. and Schnetzer, Astrid and Fu, Feixue and Hurd, Catriona L. and Boyd, Philip W. and Caron, David A. and Lie, Alle A. Y. and Hoffmann, Linn J. and Hutchins, David A.}, year={2013}, month={Oct}, pages={20120437} }
 @article{lie_kim_schnetzer_caron_2013, title={Small-scale temporal and spatial variations in protistan community composition at the San Pedro Ocean Time-series station off the coast of southern California}, volume={70}, ISSN={["1616-1564"]}, DOI={10.3354/ame01652}, abstractNote={Small-scale spatial and temporal variabiliy in protistan community composition was investigated at the USC San Pedro Ocean Time-series (SPOT) station and contrasted with a 10 yr (2000 to 2010) dataset of samples collected at approximately monthly intervals from the same station. Surface seawater samples were collected for 12 consecutive days at the SPOT station, and an addi- tional 17 stations (16 within a grid surrounding the SPOT station and 1 outlying station; 2 to 21 km apart) were sam- pled during 1 of the 12 sampling days, to investigate the small-scale temporal and spatial variability, respectively. Terminal restriction fragment length polymorphism (T-RFLP) analysis of the 18S rRNA gene was used to gen- erate DNA fingerprints of the protistan community, which were used for the calculation of pair-wise Bray-Curtis and Jaccard similarity values at different spatial and temporal scales. Temperature, salinity, pH, wind, and upwelling did not appear to have any significant effect on commu- nity composition, and distance had a weak correlation with the similarity indices generated from spatial sam- ples. Communities separated by the smallest spatial scales (0 to 2 km) had significantly higher average similar- ity than communities separated by small temporal scales (1 to 9 d). Comparisons with a 10 yr dataset of monthly samples revealed significantly lower average similarity values among communities separated by time periods ≥ 1 mo (45 to 52%) compared to communities separated by the smallest spatial (0 to 2 km; 67 to 71%) and temporal (1 d; 64%) scales. Our results indicate that small-scale spatial and day-to-day variability of protistan communi- ties was overshadowed by monthly, seasonal, and inter- annual variabilities.}, number={2}, journal={AQUATIC MICROBIAL ECOLOGY}, author={Lie, Alle A. Y. and Kim, Diane Y. and Schnetzer, Astrid and Caron, David A.}, year={2013}, pages={93-+} }
 @article{seubert_trussell_eagleton_schnetzer_cetinić_lauri_jones_caron_2012, title={Algal toxins and reverse osmosis desalination operations: Laboratory bench testing and field monitoring of domoic acid, saxitoxin, brevetoxin and okadaic acid}, volume={46}, ISSN={0043-1354}, url={http://dx.doi.org/10.1016/j.watres.2012.09.042}, DOI={10.1016/j.watres.2012.09.042}, abstractNote={The occurrence and intensity of harmful algal blooms (HABs) have been increasing globally during the past few decades. The impact of these events on seawater desalination facilities has become an important topic in recent years due to enhanced societal interest and reliance on this technology for augmenting world water supplies. A variety of harmful bloom-forming species of microalgae occur in southern California, as well as many other locations throughout the world, and several of these species are known to produce potent neurotoxins. These algal toxins can cause a myriad of human health issues, including death, when ingested via contaminated seafood. This study was designed to investigate the impact that algal toxin presence may have on both the intake and reverse osmosis (RO) desalination process; most importantly, whether or not the naturally occurring algal toxins can pass through the RO membrane and into the desalination product. Bench-scale RO experiments were conducted to explore the potential of extracellular algal toxins contaminating the RO product. Concentrations exceeding maximal values previously reported during natural blooms were used in the laboratory experiments, with treatments comprised of 50 μg/L of domoic acid (DA), 2 μg/L of saxitoxin (STX) and 20 μg/L of brevetoxin (PbTx). None of the algal toxins used in the bench-scale experiments were detectable in the desalinated product water. Monitoring for intracellular and extracellular concentrations of DA, STX, PbTx and okadaic acid (OA) within the intake and desalinated water from a pilot RO desalination plant in El Segundo, CA, was conducted from 2005 to 2009. During the five-year monitoring period, DA and STX were detected sporadically in the intake waters but never in the desalinated water. PbTx and OA were not detected in either the intake or desalinated water. The results of this study demonstrate the potential for HAB toxins to be inducted into coastal RO intake facilities, and the ability of typical RO operations to effectively remove these toxins.}, number={19}, journal={Water Research}, publisher={Elsevier BV}, author={Seubert, Erica L. and Trussell, Shane and Eagleton, John and Schnetzer, Astrid and Cetinić, Ivona and Lauri, Phil and Jones, Burton H. and Caron, David A.}, year={2012}, month={Dec}, pages={6563–6573} }
 @article{stauffer_gellene_schnetzer_seubert_oberg_sukhatme_caron_2012, title={An oceanographic, meteorological, and biological ‘perfect storm’ yields a massive fish kill}, volume={468}, url={http://dx.doi.org/10.3354/meps09927}, DOI={10.3354/meps09927}, abstractNote={Mass mortality events are ephemeral phenomena in marine ecosystems resulting from anthropogenically enhanced and natural processes. A fish kill in King Harbor, Redondo Beach, California, USA, in March 2011 killed ~1.54 × 10 5 kg of fish and garnered international attention as a marine system out of balance. Here, we present data collected prior to, during, and following the event that describe the oceanographic conditions preceding the event, spatial extent of hypoxia (dissolved oxygen 10 d following the event. Initial recovery of dissolved oxygen in the harbor was facilitated by storm-mediated mixing. No connection was apparent between increased algal biomass or phycotoxins within the harbor and the mortality event, although the fish showed evidence of prior exposure to the algal neurotoxin domoic acid. Our findings underscore the essential role of ocean observing and rapid response in the study of these events and the role that oceanographic processes play in hypoxia-driven fish mortalities. Alterations in upwelling regimes as a consequence of climate change are likely to further increase the frequency and magnitude of upwelling-driven hypoxia and mortality events.}, journal={Marine Ecology Progress Series}, publisher={Inter-Research Science Center}, author={Stauffer, BA and Gellene, AG and Schnetzer, A and Seubert, EL and Oberg, C and Sukhatme, GS and Caron, DA}, year={2012}, month={Nov}, pages={231–243} }
 @article{stauffer_schnetzer_gellene_oberg_sukhatme_caron_2012, title={Effects of an Acute Hypoxic Event on Microplankton Community Structure in a Coastal Harbor of Southern California}, volume={36}, ISSN={1559-2723 1559-2731}, url={http://dx.doi.org/10.1007/S12237-012-9551-6}, DOI={10.1007/S12237-012-9551-6}, number={1}, journal={Estuaries and Coasts}, publisher={Springer Science and Business Media LLC}, author={Stauffer, Beth A. and Schnetzer, Astrid and Gellene, Alyssa G. and Oberg, Carl and Sukhatme, Gaurav S. and Caron, David A.}, year={2012}, month={Sep}, pages={135–148} }
 @article{caron_countway_jones_kim_schnetzer_2012, title={Marine Protistan Diversity}, volume={4}, url={http://dx.doi.org/10.1146/annurev-marine-120709-142802}, DOI={10.1146/annurev-marine-120709-142802}, abstractNote={ Protists have fascinated microbiologists since their discovery nearly 350 years ago. These single-celled, eukaryotic species span an incredible range of sizes, forms, and functions and, despite their generally diminutive size, constitute much of the genetic diversity within the domain Eukarya. Protists in marine ecosystems play fundamental ecological roles as primary producers, consumers, decomposers, and trophic links in aquatic food webs. Much of our knowledge regarding the diversity and ecological activities of these species has been obtained during the past half century, and only within the past few decades have hypotheses depicting the evolutionary relationships among the major clades of protists attained some degree of consensus. This recent progress is attributable to the development of genetic approaches, which have revealed an unexpectedly large diversity of protists, including cryptic species and previously undescribed clades of protists. New genetic tools now exist for identifying protistan species of interest and for reexamining long-standing debates regarding the biogeography of protists. Studies of protistan diversity provide insight regarding how species richness and community composition contribute to ecosystem function. These activities support the development of predictive models that describe how microbial communities will respond to natural or anthropogenically mediated changes in environmental conditions. }, number={1}, journal={Annual Review of Marine Science}, publisher={Annual Reviews}, author={Caron, David A. and Countway, Peter D. and Jones, Adriane C. and Kim, Diane Y. and Schnetzer, Astrid}, year={2012}, month={Jan}, pages={467–493} }
 @article{howard_jones_schnetzer_countway_tomas_kudela_hayashi_chia_caron_2012, title={QUANTITATIVE REAL-TIME POLYMERASE CHAIN REACTION FOR COCHLODINIUM FULVESCENS (DINOPHYCEAE), A HARMFUL DINOFLAGELLATE FROM CALIFORNIA COASTAL WATERS1}, volume={48}, url={http://dx.doi.org/10.1111/j.1529-8817.2012.01120.x}, DOI={10.1111/j.1529-8817.2012.01120.x}, abstractNote={Harmful blooms formed by species of the dinoflagellate Cochlodinium have caused massive fish kills and substantial economic losses in the Pacific Ocean. Recently, prominent blooms of Cochlodinium have occurred in central and southern California (2004–2008), and Cochlodinium cells are now routinely observed in microscopical analysis of algal assemblages from Californian coastal waters. The first documented economic loss due to a Cochlodinium bloom in California occurred in Monterey Bay and resulted in the mortality of commercially farmed abalone. Increasing occurrences of Cochlodinium blooms, the fact that these cells preserve poorly using standard techniques, and the difficulty of identifying preserved specimens using morphological criteria make Cochlodinium species prime candidates for the development of a quantitative real‐time polymerase chain reaction (qPCR) approach. The 18S rDNA gene sequenced from Cochlodinium cells obtained from California coastal waters, as well as GenBank sequences of Cochlodinium, were used to design and test a Molecular Beacon® approach. The qPCR method developed in this study is species specific, sensitive for the detection of C. fulvescens that has given rise to the recent blooms in the eastern Pacific Ocean, and spans a dynamic abundance range of seven orders of magnitude. Initial application of the method to archived field samples collected during blooms in Monterey Bay revealed no statistically significant correlations between gene copy number and environmental parameters. However, the onset of Cochlodinium blooms in central California was consistent with previously reported findings of correlations to decreased surface temperature and increased inputs of nitrogenous nutrients.}, number={2}, journal={Journal of Phycology}, publisher={Wiley}, author={Howard, Meredith D. A. and Jones, Adriane C. and Schnetzer, Astrid and Countway, Peter D. and Tomas, Carmelo R. and Kudela, Raphael M. and Hayashi, Kendra and Chia, Pamela and Caron, David A.}, year={2012}, month={Apr}, pages={384–393} }
 @article{schnetzer_moorthi_countway_gast_gilg_caron_2011, title={Depth matters: Microbial eukaryote diversity and community structure in the eastern North Pacific revealed through environmental gene libraries}, volume={58}, ISSN={0967-0637}, url={http://dx.doi.org/10.1016/j.dsr.2010.10.003}, DOI={10.1016/j.dsr.2010.10.003}, abstractNote={Protistan community structure was examined from 6 depths (1.5, 20, 42, 150, 500, 880 m) at a coastal ocean site in the San Pedro Channel, California. A total of 856 partial length 18S rDNA protistan sequences from the six clone libraries were analyzed to characterize diversity present at each depth. The sequences were grouped into a total of 259 Operational Taxonomic Units (OTUs) that were inferred using an automated OTU calling program that formed OTUs with approximately species-level distinction (95% sequence similarity). Most OTUs (194 out of 259) were observed at only one specific depth, and only two were present in clone libraries from all depths. OTUs were obtained from 21 major protistan taxonomic groups determined by their closest BLAST matches to identified protists in the NCBI database. Approximately 74% of the detected OTUs belonged to the Chromalveolates, with Group II alveolates making up the largest single group. Protistan assemblages at euphotic depths (1.5, 20 and 42 m) were characterized by the presence of clades that contained phototrophic species (stramenopiles, chlorophytes and haptophytes) as well as consumers (especially ciliates). Assemblages in the lower water column (150, 500 and 800 m) were distinct from communities at shallow depths because of strong contributions from taxa belonging to euglenozoans, acantharians, polycystines and Taxopodida (Sticholonche spp. and close relatives). Species richness (Chao I estimate) and diversity (Shannon index) were highest within the euphotic zone and at 150 m, and lowest for protistan assemblages located in the oxygen minimum zone (500 and 880 m). Multivariate analyses (Bray–Curtis coefficient) confirmed that protistan assemblage composition differed significantly when samples were grouped into shallow (≤150 m) and deep water assemblages (≥150 m).}, number={1}, journal={Deep Sea Research Part I: Oceanographic Research Papers}, publisher={Elsevier BV}, author={Schnetzer, Astrid and Moorthi, Stefanie D. and Countway, Peter D. and Gast, Rebecca J. and Gilg, Ilana C. and Caron, David A.}, year={2011}, month={Jan}, pages={16–26} }
 @article{garneau_schnetzer_countway_jones_seubert_caron_2011, title={Examination of the Seasonal Dynamics of the Toxic Dinoflagellate Alexandrium catenella at Redondo Beach, California, by Quantitative PCR}, volume={77}, url={http://dx.doi.org/10.1128/aem.06174-11}, DOI={10.1128/aem.06174-11}, abstractNote={ABSTRACT}, number={21}, journal={Applied and Environmental Microbiology}, publisher={American Society for Microbiology}, author={Garneau, Marie-Ève and Schnetzer, Astrid and Countway, Peter D. and Jones, Adriane C. and Seubert, Erica L. and Caron, David A.}, year={2011}, month={Nov}, pages={7669–7680} }
 @article{fitzpatrick_caron_schnetzer_2010, title={Development and environmental application of a genus-specific quantitative PCR approach for Pseudo-nitzschia species}, volume={157}, ISSN={0025-3162 1432-1793}, url={http://dx.doi.org/10.1007/s00227-009-1383-y}, DOI={10.1007/s00227-009-1383-y}, number={5}, journal={Marine Biology}, publisher={Springer Science and Business Media LLC}, author={Fitzpatrick, Elizabeth and Caron, David A. and Schnetzer, Astrid}, year={2010}, month={Jan}, pages={1161–1169} }
 @article{caron_garneau_seubert_howard_darjany_schnetzer_cetinić_filteau_lauri_jones_2010, title={Harmful algae and their potential impacts on desalination operations off southern California}, volume={44}, ISSN={0043-1354}, url={http://dx.doi.org/10.1016/j.watres.2009.06.051}, DOI={10.1016/j.watres.2009.06.051}, abstractNote={Seawater desalination by reverse osmosis (RO) is a reliable method for augmenting drinking water supplies. In recent years, the number and size of these water projects have increased dramatically. As freshwater resources become limited due to global climate change, rising demand, and exhausted local water supplies, seawater desalination will play an important role in the world's future water supply, reaching far beyond its deep roots in the Middle East. Emerging contaminants have been widely discussed with respect to wastewater and freshwater sources, but also must be considered for seawater desalination facilities to ensure the long-term safety and suitability of this emerging water supply. Harmful algal blooms, frequently referred to as 'red tides' due to their vibrant colors, are a concern for desalination plants due to the high biomass of microalgae present in ocean waters during these events, and a variety of substances that some of these algae produce. These compounds range from noxious substances to powerful neurotoxins that constitute significant public health risks if they are not effectively and completely removed by the RO membranes. Algal blooms can cause significant operational issues that result in increased chemical consumption, increased membrane fouling rates, and in extreme cases, a plant to be taken off-line. Early algal bloom detection by desalination facilities is essential so that operational adjustments can be made to ensure that production capacity remains unaffected. This review identifies the toxic substances, their known producers, and our present state of knowledge regarding the causes of toxic episodes, with a special focus on the Southern California Bight.}, number={2}, journal={Water Research}, publisher={Elsevier BV}, author={Caron, David A. and Garneau, Marie-Ève and Seubert, Erica and Howard, Meredith D.A. and Darjany, Lindsay and Schnetzer, Astrid and Cetinić, Ivona and Filteau, Gerry and Lauri, Phil and Jones, Burton}, year={2010}, month={Jan}, pages={385–416} }
 @article{gilg_amaral-zettler_countway_moorthi_schnetzer_caron_2010, title={Phylogenetic Affiliations of Mesopelagic Acantharia and Acantharian-like Environmental 18S rRNA Genes off the Southern California Coast}, volume={161}, ISSN={1434-4610}, url={http://dx.doi.org/10.1016/j.protis.2009.09.002}, DOI={10.1016/j.protis.2009.09.002}, abstractNote={Incomplete knowledge of acantharian life cycles has hampered their study and limited our understanding of their role in the vertical flux of carbon and strontium. Molecular tools can help identify enigmatic life stages and offer insights into aspects of acantharian biology and evolution. We inferred the phylogenetic position of acantharian sequences from shallow water, as well as acantharian-like clone sequences from 500 and 880 m in the San Pedro Channel, California. The analyses included validated acantharian and polycystine sequences from public databases with environmental clone sequences related to acantharia and used Bayesian inference methods. Our analysis demonstrated strong support for two branches of unidentified organisms that are closely related to, but possibly distinct from the Acantharea. We also found evidence of acantharian sequences from mesopelagic environments branching within the chaunacanthid clade, although the morphology of these organisms is presently unknown. HRP-conjugated probes were developed to target Acantharea and phylotypes from Unidentified Clade 1 using Catalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) on samples collected at 500 m. Our CARD-FISH experiments targeting phylotypes from an unidentified clade offer preliminary glimpses into the morphology of these protists, while a morphology for the aphotic acantharian lineages remains unknown at this time.}, number={2}, journal={Protist}, publisher={Elsevier BV}, author={Gilg, Ilana C. and Amaral-Zettler, Linda A. and Countway, Peter D. and Moorthi, Stefanie and Schnetzer, Astrid and Caron, David A.}, year={2010}, month={Apr}, pages={197–211} }
 @article{countway_vigil_schnetzer_moorthi_caron_2010, title={Seasonal analysis of protistan community structure and diversity at the USC Microbial Observatory (San Pedro Channel, North Pacific Ocean)}, volume={55}, url={http://dx.doi.org/10.4319/lo.2010.55.6.2381}, DOI={10.4319/lo.2010.55.6.2381}, abstractNote={The structure and genetic diversity of marine protistan assemblages were investigated in the upper 500 m of the water column at a Pacific Ocean time‐series station off the coast of Southern California. Deoxyribonucleic acid sequence‐based microbial eukaryote diversity was examined in January, April, July, and October of 2001 at four depths (5 m, chlorophyll maximum [CM], 150 m, and 500 m). A total of 2956 partial 18S ribosomal ribonucleic acid gene sequences yielded representatives from most of the major eukaryotic lineages. Notable among the taxonomic groups were recently described lineages of stramenopiles, alveolates, and euglenozoa. A large number of polycystine and acantharean sequences were observed at depth. Pairwise sequence analysis was performed to establish operational taxonomic units (OTUs) that were then used to estimate the unsampled protistan diversity by parametric and nonparametric techniques. A total of 2246 protistan sequences grouped into 377 distinct OTUs, with remaining sequences attributed to metazoa. Protistan richness estimates ranged from ~ 600 to 1500 OTUs when all depths and seasons were combined into a single data set. Seasonal and depth‐related trends in the observed protistan diversity were apparent from comparisons of univariate and multivariate analyses. Cluster analysis combined with nonmetric multidimensional scaling and analysis of similarity testing identified distinct protistan assemblages at the shallowest depths (5 m and CM) for each season, which were significantly different (p < 0.03) from assemblages at the two deepest depths (150 and 500 m) where seasonal changes in the protistan assemblage were not apparent.}, number={6}, journal={Limnology and Oceanography}, publisher={Wiley}, author={Countway, Peter D. and Vigil, Patrick D. and Schnetzer, Astrid and Moorthi, Stefanie D. and Caron, David A.}, year={2010}, month={Nov}, pages={2381–2396} }
 @article{smith_das_heidarsson_pereira_arrichiello_cetnic_darjany_garneau_howard_oberg_et al._2010, title={USC CINAPS Builds Bridges}, volume={17}, url={http://dx.doi.org/10.1109/mra.2010.935795}, DOI={10.1109/mra.2010.935795}, abstractNote={More than 70% of our earth is covered by water, yet we have explored less than 5% of the aquatic environment. Aquatic robots, such as autonomous underwater vehicles (AUVs), and their supporting infrastructure play a major role in the collection of oceanographic data. To make new discoveries and improve our overall understanding of the ocean, scientists must make use of these platforms by implementing effective monitoring and sampling techniques to study ocean upwelling, tidal mixing, and other ocean processes. Effective observation and continual monitoring of a dynamic system as complex as the ocean cannot be done with one instrument in a fixed location. A more practical approach is to deploy a collection of static and mobile sensors, where the information gleaned from the acquired data is distributed across the network. Additionally, orchestrating a multisensor, long-term deployment with a high volume of distributed data involves a robust, rapid, and cost-effective communication network. Connecting all of these components, which form an aquatic robotic system, in synchronous operation can greatly assist the scientists in improving our overall understanding of the complex ocean environment.}, number={1}, journal={IEEE Robotics & Automation Magazine}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Smith, Ryan and Das, Jnaneshwar and Heidarsson, Hordur and Pereira, Arvind and Arrichiello, Filippo and Cetnic, Ivona and Darjany, Lindsay and Garneau, Marie-Eve and Howard, Meredith and Oberg, Carl and et al.}, year={2010}, month={Mar}, pages={20–30} }
 @article{caron_countway_savai_gast_schnetzer_moorthi_dennett_moran_jones_2009, title={Defining DNA-Based Operational Taxonomic Units for Microbial-Eukaryote Ecology}, volume={75}, url={http://dx.doi.org/10.1128/aem.00298-09}, DOI={10.1128/aem.00298-09}, abstractNote={ABSTRACT}, number={18}, journal={Applied and Environmental Microbiology}, publisher={American Society for Microbiology}, author={Caron, David A. and Countway, Peter D. and Savai, Pratik and Gast, Rebecca J. and Schnetzer, Astrid and Moorthi, Stefanie D. and Dennett, Mark R. and Moran, Dawn M. and Jones, Adriane C.}, year={2009}, month={Sep}, pages={5797–5808} }
 @article{sekula-wood_schnetzer_benitez-nelson_anderson_berelson_brzezinski_burns_caron_cetinic_ferry_et al._2009, title={Rapid downward transport of the neurotoxin domoic acid in coastal waters}, volume={2}, ISSN={1752-0894 1752-0908}, url={http://dx.doi.org/10.1038/ngeo472}, DOI={10.1038/ngeo472}, number={4}, journal={Nature Geoscience}, publisher={Springer Science and Business Media LLC}, author={Sekula-Wood, Emily and Schnetzer, Astrid and Benitez-Nelson, Claudia R. and Anderson, Clarissa and Berelson, William M. and Brzezinski, Mark A. and Burns, Justina M. and Caron, David A. and Cetinic, Ivona and Ferry, John L. and et al.}, year={2009}, month={Mar}, pages={272–275} }
 @article{tracking toxins_2009, volume={2}, ISSN={1752-0894 1752-0908}, url={http://dx.doi.org/10.1038/NGEO488}, DOI={10.1038/NGEO488}, number={4}, journal={Nature Geoscience}, publisher={Springer Science and Business Media LLC}, year={2009}, month={Mar}, pages={E5–E5} }
 @article{litaker_stewart_eberhart_wekell_trainer_kudela_miller_roberts_hertz_johnson_et al._2008, title={Rapid Enzyme-linked Immunosorbent Assay for Detection of the Algal Toxin Domoic Acid}, volume={27}, url={http://dx.doi.org/10.2983/0730-8000-27.5.1301}, DOI={10.2983/0730-8000-27.5.1301}, abstractNote={Abstract Domoic acid (DA) is a potent toxin produced by bloom-forming phytoplankton in the genus Pseudo-nitzschia, which is responsible for causing amnesic shellfish poisoning (ASP) in humans. ASP symptoms include vomiting, diarrhea, and in more severe cases confusion, loss of memory, disorientation, and even coma or death. This paper describes the development and validation of a rapid, sensitive, enzyme linked immunosorbent assay test kit for detecting DA using a monoclonal antibody. The assay gives equivalent results to those obtained using standard high performance liquid chromatography, fluorenylmethoxycarbonyl high performance liquid chromatography, or liquid chromatography—mass spectrometry methods. It has a linear range from 0.1–3 ppb and was used successfully to measure DA in razor clams, mussels, scallops, and phytoplankton. The assay requires approximately 1.5 h to complete and has a standard 96-well format where each strip of eight wells is removable and can be stored at 4°C until needed. The first two wells of each strip serve as an internal control eliminating the need to run a standard curve. This allows as few as 3 or as many as 36 duplicate samples to be run at a time enabling real-time sample processing and limiting degradation of DA, which can occur during storage. There was minimal cross-reactivity in this assay with glutamine, glutamic acid, kainic acid, epi- or iso-DA. This accurate, rapid, cost-effective, assay offers environmental managers and public health officials an effective tool for monitoring DA concentrations in environment samples.}, number={5}, journal={Journal of Shellfish Research}, publisher={National Shellfisheries Association}, author={Litaker, R. Wayne and Stewart, Thomas N. and Eberhart, Bich-Thuy L. and Wekell, John C. and Trainer, Vera L. and Kudela, Raphael M. and Miller, Peter E. and Roberts, Alice and Hertz, Cassandra and Johnson, Tyler A. and et al.}, year={2008}, month={Dec}, pages={1301–1310} }
 @article{schnetzer_miller_schaffner_stauffer_jones_weisberg_digiacomo_berelson_caron_2007, title={Blooms of Pseudo-nitzschia and domoic acid in the San Pedro Channel and Los Angeles harbor areas of the Southern California Bight, 2003–2004}, volume={6}, ISSN={1568-9883}, url={http://dx.doi.org/10.1016/j.hal.2006.11.004}, DOI={10.1016/j.hal.2006.11.004}, abstractNote={Abundances of Pseudo-nitzschia spp. and concentrations of particulate domoic acid (DA) were determined in the Southern California Bight (SCB) along the coasts of Los Angeles and Orange Counties during spring and summer of 2003 and 2004. At least 1500 km2 were affected by a toxic event in May/June of 2003 when some of the highest particulate DA concentrations reported for US coastal waters were measured inside the Los Angeles harbor (12.7 μg DA L−1). Particulate DA levels were an order of magnitude lower in spring of 2004 (February and March), but DA concentrations per cell at several sampling stations during 2004 exceeded previously reported maxima for natural populations of Pseudo-nitzschia (mean = 24 pg DA cell−1, range = 0–117 pg DA cell−1). Pseudo-nitzschia australis dominated the Pseudo-nitzschia assemblage in spring 2004. Overall, DA-poisoning was implicated in >1400 mammal stranding incidents within the SCB during 2003 and 2004. Ancillary physical and chemical data obtained during our regional surveys in 2004 revealed that Pseudo-nitzschia abundances, particulate DA and cellular DA concentrations were inversely correlated with concentrations of silicic acid, nitrogen and phosphate, and to specific nutrient ratios. Particulate DA was detected in sediment traps deployed at 550 and 800 m depth during spring of 2004 (0.29–7.6 μg DA (g sediment dry weight)−1). The highest DA concentration in the traps was measured within 1 week of dramatic decreases in the abundances of Pseudo-nitzschia in surface waters. To our knowledge these are the deepest sediment trap collections from which DA has been detected. Sinking of the spring Pseudo-nitzschia bloom may constitute a potentially important link between DA production in surface waters and benthic communities in the coastal ocean near Los Angeles. Our study indicates that toxic blooms of Pseudo-nitzschia are a recurring phenomenon along one of the most densely populated coastal stretches of the SCB and that the severity and magnitude of these events can be comparable to or greater than these events in other geographical regions affected by domoic acid.}, number={3}, journal={Harmful Algae}, publisher={Elsevier BV}, author={Schnetzer, Astrid and Miller, Peter E. and Schaffner, Rebecca A. and Stauffer, Beth A. and Jones, Burton H. and Weisberg, Stephen B. and DiGiacomo, Paul M. and Berelson, William M. and Caron, David A.}, year={2007}, month={Apr}, pages={372–387} }
 @article{occurrence and removal of marine biotoxins for the seawater reverse osmosis treatment process: phytoplankton and domoic acid correlations at the west basin mwd seawater desalination pilot plant in el segundo, ca_2007, journal={American Membrane Technology Association}, year={2007}, month={Jan} }
 @inbook{protistan community structure_2006, booktitle={Manual of Environmental Microbiology}, year={2006}, month={Jan} }
 @article{schnetzer_caron_2005, title={Copepod grazing impact on the trophic structure of the microbial assemblage of the San Pedro Channel, California}, volume={27}, url={http://dx.doi.org/10.1093/plankt/fbi049}, DOI={10.1093/plankt/fbi049}, abstractNote={In August 2002 and March 2003 the trophic structure of the microbial assemblage from the San Pedro Channel, California was studied following the experimental alteration of the number of copepods. Changes in the abundance/biomass of microorganisms 80 μm, (ii) the presence of natural abundances of metazoa and (iii) the presence of an elevated number of copepods. Prokaryotes and small-sized eukaryotes (<4 μm) dominated plankton biomass during both experimental months. Diatoms numerically dominated the 10-80 μm plankton in August 2002, but ciliate and heterotrophic dinoflagellate biomass generally exceeded diatom biomass on both dates. Ingestion of protozooplankton (predominantly ciliates) contributed substantially to copepod daily carbon rations. The adult copepod assemblage removed 4.6 and 36% per day of the microzooplankton standing stocks (10-80 μm size fraction) in August and March, respectively. Elevated copepod grazing pressure on protozooplankton resulted in increased biomass of nanoplankton (<5 μm) presumably via a trophic cascade. Accordingly, the copepod-protozoan trophic link appears to be a key factor structuring the planktonic microbial assemblage in the San Pedro Channel.}, number={10}, journal={Journal of Plankton Research}, publisher={Oxford University Press (OUP)}, author={Schnetzer, Astrid and Caron, David A.}, year={2005}, month={Oct}, pages={959–971} }
 @article{schnetzer_steinberg_2002, title={Active transport of particulate organic carbon and nitrogen by vertically migrating zooplankton in the Sargasso Sea}, volume={234}, url={http://dx.doi.org/10.3354/meps234071}, DOI={10.3354/meps234071}, abstractNote={Diel vertically migrating zooplankton can contribute significantly to dissolved carbon and nutrient export by respiring and excreting surface-ingested particulate organic matter below the mixed layer. Active export of particulate organic carbon (POC) and particulate organic nitrogen (PON) due to defecation at depth has rarely been considered in export budgets. We measured the gut passage time (GPT) of common migrant species at the Bermuda Atlantic Time-series Study (BATS) site, using the gut fluorescence method, to determine whether GPT is slow enough to allow active export of POC and PON to depth. Mean GPT for the copepods Pleuromamma xiphias and Euchirella messinensis was 191 and 114 min, respectively, and for the euphausiids Thysanopoda aequalis and Euphausia brevis (analyzed together) was 41 min, exceeding previously reported GPT for non- migrating zooplankton by a factor of 6. Between 18 and 81% of the initial gut pigment was retained in zooplankton guts upon descent below a mixed layer of 150 m. By comparing pigment ingestion rates (gut fluorescence technique) with total ingestion rates (CHN analysis of fecal material), we esti- mated that 71 to 85% of the migrant diet originated from non-plant material, which we included in our estimates of active POC/PON export. We applied the mean weight-specific active POC/PON export rate for the species examined to the total migratory zooplankton biomass using data from the BATS zooplankton time-series. Mean active POC (PON) flux at BATS was 0.94 mg C m -2 d -1 (0.18 mg N m -2 d -1 ) and the maximum was 5.27 mg C m -2 d -1 (1.02 mg N m -2 d -1 ), corresponding to a mean of 3% (4%) and a maximum of 18% (20%) of the mean gravitational POC (PON) flux measured by sediment traps at 150 m. Migrants also contributed significantly to passive flux via production of sinking fecal pellets during the night in surface waters. This passive flux exceeded active POC flux by ~10-fold. Freshly released feces by migrators at depth could be a valuable food source for mesopelagic organisms, in contrast to feces produced in surface waters which decompose while settling through the water column.}, journal={Marine Ecology Progress Series}, publisher={Inter-Research Science Center}, author={Schnetzer, A and Steinberg, DK}, year={2002}, pages={71–84} }
 @article{a._d._2002, title={Natural diets of vertically migrating zooplankton in the Sargasso Sea}, volume={141}, url={http://dx.doi.org/10.1007/s00227-002-0815-8}, DOI={10.1007/s00227-002-0815-8}, number={1}, journal={Marine Biology}, publisher={Springer Science and Business Media LLC}, author={A., Schnetzer and D., Steinberg}, year={2002}, month={Jul}, pages={89–99} }