SFS Annual Meeting

5/20/2019  |   14:00 - 14:15   |  150 DEF

A QUICK TOUR THROUGH THE NATION’S FINE-SCALE NITRATE DYNAMICS; QUANTIFYING NUTRIENT VARIABILITY OVER THE COURSE OF 24 HOURS The amount of nitrate in streams is important for ecological and human water use, and variability in this metric can range in timescales from hours to decades. Though seasonal and year-to-year dynamics have been well studied, sub-daily dynamics are poorly understood, yet are immediately important to human and other biological water users. With the growing number of high-frequency nitrate data sets, we are now able to look at how variability over the course of a day may compare to weekly, monthly, and seasonal variability. This study looks at >100 high-frequency nitrate data sets and aims to quantify and describe the within-day variation of these constituents over a range of geographic locations, flow conditions, and seasonality. We synthesize these data using multiple forms of analysis to characterize different nutrient ‘regimes’ seen in the nations’ waters. Preliminary analysis has shown that the within-day variation of nitrate across streams is considerable, with an average concentration range of 0.2 mg/L and maximums of over 20 mg/L. Given that the median nitrate concentration across these days is ~2 mg/L, this can represent a variation of 10% or more.

Catherine Chamberlin (Primary Presenter/Author), Duke University, catherine.chamberlin@duke.edu;


Jim Heffernan (Co-Presenter/Co-Author), Duke University, james.heffernan@duke.edu;


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5/20/2019  |   14:15 - 14:30   |  150 DEF

CHARACTERIZING NUISANCE ALGAL RESPONSES TO ENVIRONMENTAL STRESSORS USING HIGH-THROUGHPUT SEQUENCING Bloom-forming and toxin-producing algae can decrease ecological condition, impair drinking water, and prevent recreational use of streams and rivers. Little is known about how nuisance algae in streams respond to drought, nutrient pollution, and pesticide contamination. DNA metabarcoding offers a time- and cost-effective alternative to traditional morphological analysis to increase nuisance algal detection in stream biofilms. Predictive modeling can be used to understand how environmental stressors affect taxon presence. I present results comparing the sensitivity of morphology-based counts and 23S rRNA DNA metabarcoding in detecting key nuisance algae genera and their relationships to environmental stressors across 95 northeastern United States streams along an urban gradient. We identified the cyanobacteria Anabaena, Lyngbya, Microcystis, and Nostoc; the green algae Cladophora, Mougeotia, and Zygnema; Euglena; and the diatom Didymosphenia as potential nuisance algae in streams. For each genus, we constructed predictive models using taxon presence/absence and stream hydrology, nutrients, major ions, and pesticides to determine likelihoods of nuisance algae occurrence in impacted streams. Our results suggest DNA-based methods and predictive modeling can determine conditions in which nuisance algae affect water quality for human use.

Daren Carlisle (Co-Presenter/Co-Author), U.S. Geological Survey, dcarlisle@usgs.gov;


Sarah Spaulding (Co-Presenter/Co-Author), U.S. Geological Survey, Institute of Arctic and Alpine Research, University of Colorado Boulder, sarah.spaulding@colorado.edu;


Nicholas Schulte (Primary Presenter/Author), Institute of Arctic and Alpine Research, University of Colorado Boulder, nicholas.schulte@colorado.edu;


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5/20/2019  |   14:30 - 14:45   |  150 DEF

DETECTING WATER QUALITY THRESHOLDS FOR ALGAL BLOOMS USING A SHORT-TERM, MULTI-SPECIES ASSAY A strong mechanistic understanding of algal responses to environmental conditions is needed to predict and manage harmful algal blooms (HABs). Typically this understanding is gained with laboratory cultures where growth and biochemical responses can be isolated, or through rigorous field-based correlation studies. Given inherent limitations such as the inability to culture some species, unknown species interactions, and intrinsic variability in field studies, additional approaches are needed to better assess many species. We are developing a Fourier-Transform infrared microspectroscopy based method that can measure biochemical changes in individual algae at the cellular level on a time scale of hours to days. Additionally, target species do not need to be isolated during incubation. We are using the nuisance diatom Didymosphenia geminata and green alga Cladophora, which can both produce abundant biomass that blanket stream bottoms, as model algae. FTIR microspectroscopy is being used to pinpoint water quality thresholds that trigger protein production for cell division, or carbohydrate and lipid production often observed in nutrient-stressed algae. This approach allows a relatively quick assessment of individual species within multi-species incubation, which may provide a more accurate assessment of HAB triggers in streams and lakes.

Justin Murdock (Primary Presenter/Author), Tennessee Technological University, jnmurdock@tntech.edu;


Samuel Day (Co-Presenter/Co-Author), Tennessee Tech University, sjday42@students.tntech.edu;


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5/20/2019  |   14:45 - 15:00   |  150 DEF

DIDYMOSPHENIA GEMINATA DISTRIBUTION IN SOUTHERN APPALACHIAN WATERSHEDS Tailwaters of hypolimnetic release dams in the southeastern U.S. are often cooler and have less nutrients than unregulated streams in the region. These environmental characteristics can support Didymosphenia geminata mats that cover substrata, alter benthic food webs, and may degrade fish habitat. Didymosphenia geminata’s distribution in the Southeast has not been extensively delineated as reports often only come when mats have developed. Recent studies suggest multiple environmental variables may be facilitating its presence in the Southern Appalachians. A survey was conducted to determine D. geminata presence in eastern Tennessee and western North Carolina rivers during the summer of 2018. Random Forest analysis was used to relate water chemistry and habitat characteristics to D. geminata distribution. Temperature, conductivity, sulfate, calcium, and chloride had the strongest relationship with cell presence. While previous studies have identified low phosphorus as the primary driver of cell state, factors associated with the underlying geology of Appalachian watersheds appear to have a stronger effect on cell colonization than phosphorus. Further delineating the environmental parameters necessary for cell colonization will improve efforts by natural resource agencies to identify streams susceptible to cell colonization and nuisance mats.

Justin Murdock (Co-Presenter/Co-Author), Tennessee Technological University, jnmurdock@tntech.edu;


Spencer Womble (Primary Presenter/Author), Tennessee Tech University, Spencer.Womble@uga.edu;


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5/20/2019  |   15:00 - 15:15   |  150 DEF

DOWNSTREAM DYNAMICS OF RESERVOIR-BORN CYANOBACTERIAL BLOOMS IN THE KLAMATH RIVER, CA Cyanobacterial blooms are often associated with lentic systems but cyanobacteria cells and cyanotoxins exported from upstream lakes or reservoirs can enter high-gradient rivers affecting ecosystem function and public health. The Klamath River experiences annual blooms dominated by toxigenic Microcystis aeruginosa that originate in warm, nutrient-rich hydroelectric reservoirs with epilimnetic outflows and persist in the river for over 300 km to the estuary. We explored longitudinal and temporal trends of M. aeruginosa cell densities, microcystin toxin, and phycocyanin fluorescence in the Klamath River from 2007 to 2017. Blooms occurred every year of the study and peaked in the river in August and September. Cell density and toxin concentration decreased longitudinally below the source reservoir due to both tributary dilution and cell loss. Cell density and toxin concentrations were often highly variable between regular weekly sampling events and within a single day. We developed relationships between the probability of toxin concentrations exceeding public health thresholds and real-time phycocyanin data that can be used to indicate changing bloom conditions in real-time. Understanding cyanobacterial dynamics in receiving waters is important for predicting the effect of source blooms on riverine ecosystem processes and public health.

Laurel Genzoli (Primary Presenter/Author), University of Montana, laurel.genzoli@umontana.edu;


Jacob Kann (Co-Presenter/Co-Author), Aquatic Ecosystem Sciences, jacob@aquatic-ecosciences.com;


Susan Fricke (Co-Presenter/Co-Author), Karuk Department of Natural Resources, sfricke@karuk.us;


Matthew Hanington (Co-Presenter/Co-Author), Yurok Tribe Environmental Program, mhanington@yuroktribe.nsn.us;


Crystal Robinson (Co-Presenter/Co-Author), Quartz Valley Indian Reservation Environmental Program, crystal.robinson@qvir-nsn.gov;


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5/20/2019  |   15:15 - 15:30   |  150 DEF

ECOHYDROLOGY OF LARGE RIVERS AND IMPLICATIONS FOR MANAGEMENT OF HARMFUL ALGAL BLOOMS The ecohydrology of large rivers is central to preventing or limiting the occurrence, frequency, and extent of harmful algal blooms such as Microcystis. River ecologists have argued for decades that the phytoplankton and food webs of large rivers are not typically nutrient limited as are lakes or headwater streams. Therefore the assumption that nutrients are the sole driver of HABs in large rivers has potentially prolonged the problem. Observation and experimental research on the Ohio River, USA, has demonstrated biota are negatively impacted by high discharge by reducing zooplankton grazing of palatable phytoplankton. At low discharge, zooplankton, particularly large-bodied species with higher grazing rates were more abundant. Additionally, Microcystis blooms have occurred historically in the Ohio during periods of drought and in late summer when discharge is reduced and more light is available. While controlling nutrient runoff is important to reduce export to oceans, inducing mixing in regulated rivers during periods of low flow may be more effective in reducing blooms by decreasing light availability, reduced competition from zooplankton grazing, and overriding phytoplankton adaptations to maintain position in the photic zone.

Tamara Sluss (Primary Presenter/Author), University of Louisville, tamara.sluss@louisville.edu;


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