SFS Annual Meeting

6/04/2024  |   15:30 - 15:45   |  Salon 5/6

How Climate Change has Impacted the Monitoring and Management of Cyanobacteria in Lakes Climate change is having a direct and substantial impact on the ecology and management lakes in the Mid-Atlantic region of the United States. These impacts include physical impacts such as thermal stratification, chemical impacts such as the availability of nutrients in the water column and over the water-sediment interface, and biological impacts such as allowing invasive species to expand their distribution. However, one of the most dramatic impacts is how climate change has impacted cyanobacteria. This presentation will review how climate change has impacted the development and distribution of cyanobacteria blooms in lakes. The focus of the presentation will be on two lakes in the Mid-Atlantic region: Harveys Lake (Luzerne County, PA) and Lake Hopatcong (Morris / Sussex Counties, NJ). Such impacts will include the increasing role internal phosphorus loading has on cyanobacteria blooms, the expansion of growing season, how increasing temperatures at the sediment / water interface foster growth, and the appearance of an invasive species of cyanobacteria. The presentation will conclude with some recommended monitoring measures to better track and predict such blooms as well as management measures to both proactively and reactively address these blooms.

Fred Lubnow (Primary Presenter/Author), Princeton Hydro, LLC, flubnow@princetonhydro.com;

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6/04/2024  |   15:45 - 16:00   |  Salon 5/6

Phytoplankton functional response to extreme climatic events in two shallow, eutrophic bays of Lake Champlain Climate change has resulted in an increase in the frequency and intensity of extreme climatic events (ECEs), such as heat waves, drought, high rainfall, and wind events with significant impacts on freshwater ecosystem function. Here we explore the effects of ECEs on phytoplankton community structure in two, shallow eutrophic bays of Lake Champlain. Utilizing five years of high frequency meteorological data, we identify ECEs in air temperature, wind speed and stream flow. We then address two primary questions using high frequency buoy data and discrete weekly samples: (1) how do ECEs effect chlorophyll and phycocyanin fluorescence, and (2) how do ECEs affect phytoplankton functional group diversity and community turnover? From 2017-2021, ECEs had variable effects on phycocyanin and chlorophyll. Phytoplankton functional groups displayed differences in their response to environmental variables, which could explain the variable responses in phycocyanin and chlorophyll fluorescence. In Missisquoi Bay, increasing frequency of extreme climatic events between sampling events resulted in increased community turnover (r2 = 0.46, p < 0.05) and decreased functional group diversity (r2 =-0.51, p <0.05), with no significant effect on phytoplankton biomass. In St. Albans Bay, increasing frequency of extreme climatic events lead to increases in biomass (r2=0.37, p<0.05), but had little effect on community turnover and diversity. Our work highlights the importance of addressing phytoplankton functional groups response to ECEs in combination with high frequency data and provides insight to how lakes may respond to increased disturbance events under future climatic scenarios.

Katelynn Warner (Primary Presenter/Author), University of Vermont, kwarner@uvm.edu;

Andrew Schroth (Co-Presenter/Co-Author), University of Vermont, aschroth@uvm.edu;

Alex Bernich (Co-Presenter/Co-Author), University of Vermont, abernich@uvm.edu;

Lindsay VanFossen (Co-Presenter/Co-Author), University of Vermont, lindsaymvf@gmail.com;

Ana Morales-Williams (Co-Presenter/Co-Author), University of Vermont, ana.morales@uvm.edu;

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6/04/2024  |   16:00 - 16:15   |  Salon 5/6

ASSESSING THE SYNCHRONICITY OF ANATOXIN-PRODUCING BENTHIC CYANOBACTERIA AND RIVER ECOSYSTEM PRODUCTIVITY Anatoxin-producing benthic cyanobacteria have been increasingly detected in rivers worldwide, yet our ability to predict the timing of their occurrence and toxin production is limited. Assessing the synchrony between reach scale river productivity and cyanobacterial dynamics may help determine the environmental factors that influence anatoxin production in rivers. From June to September in 2022 and 2023, we conducted field surveys in northern California on the South Fork Eel, Russian, and Salmon Rivers to estimate percent cover of benthic cyanobacteria Microcoleus and Anabaena and to collect surface water samples and benthic mat samples for microscopy and toxin analyses. We used high-frequency temperature and dissolved oxygen sensors to collect data to estimate daily river metabolism. In 2023, on the South Fork Eel we saw an increase in Microcoleus cover (0.0 to 8.4-22.7%) from June to September, while Anabaena cover peaked in early August and subsequently declined (0.0 to 1.5-11.9% at peak, ending at 0.0-2.0%). On the Salmon, Microcoleus also increased in cover from June until sampling interruption by wildfire in early August (0.0-0.6 to 3.5-16.4%). Preliminary metabolism estimates show peak productivity in early July in the South Fork Eel (3.2 g O2 / m^2*d) and late September in the Salmon (5.8 g O2 / m^2*d). This asynchrony suggests that the processes controlling cyanobacteria accrual may be different from those that govern the entire autotrophic community. Future work will evaluate the potential for forecasting cyanotoxin production and explore the influences of the surrounding benthic community.

Jordan Zabrecky (Primary Presenter/Author), University of Nevada, Reno, jordanmz@alumni.unc.edu;

Taryn Elliott (Co-Presenter/Co-Author), University of Nevada, Reno, taryne@unr.edu;

Meaghan Hickey (Co-Presenter/Co-Author), Vermont Department of Environmental Conservation, mhick729@gmail.com;

Rosalina Stancheva Christova (Co-Presenter/Co-Author), George Mason University, rchris13@gmu.edu;

Keith Bouma-Gregson (Co-Presenter/Co-Author), U.S. Geological Survey, kbouma-gregson@usgs.gov;

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

Rich Fadness (Co-Presenter/Co-Author), California State Water Resources Control Board, Rich.Fadness@waterboards.ca.gov;

Michael Thomas (Co-Presenter/Co-Author), California State Water Resources Control Board, Michael.Thomas@waterboards.ca.gov;

Shadman Kaiser (Co-Presenter/Co-Author), University of Utah, u1326563@utah.edu;

Abeer Sohrab (Co-Presenter/Co-Author), University of Utah, u1370694@utah.edu;

Ramesh Goel (Co-Presenter/Co-Author), University of Utah, ram.goel@utah.edu;

Robert Shriver (Co-Presenter/Co-Author), University of Nevada, Reno, rshriver@unr.edu;

Joanna Blaszczak (Co-Presenter/Co-Author), University of Nevada, Reno, jblaszczak@unr.edu;

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6/04/2024  |   16:15 - 16:30   |  Salon 5/6

EFFECTS OF CHANGES IN NITROGEN AND PHOSPHORUS ON THE SELECTION OF DOMINANT ALGAL GENERA AND MICROCYSTIN PRODUCTION IN RIVER WATER Riverine cyanobacterial blooms have become a worldwide environmental concern; however, our understanding of the mechanisms driving algal blooms in rivers remains limited. This study investigated the impact of nutrient conditions on dominant algal genera and microcystin production in large rivers. Water sourced from the Cumberland River, Tennessee, underwent a 36-day incubation, exploring four distinct nutrient scenarios of nitrogen (N) and phosphorus (P) limitation. When N was limiting, the proportion of nitrogen-fixing cyanobacteria (Dolichospermum sp.) increased with rising P, and dominated when P exceeded 0.1 mg/L. Conversely, with excessive N, the cyanobacteria Microcystis sp. increased with higher P, and became dominant when P exceeded 0.1 mg/L. When P was low, eukaryotic algae increased with rising nitrogen levels, and green algae and diatoms jointly became dominant when N surpassed 5 mg/L. However, when P was in excess, green algae dominated when N exceeded 7.5 mg/L. These results indicate that both N and P are potentially limiting algae growth in the Cumberland River. Specifically, high N increases eukaryotic algae dominance, but green algae require a higher P level than diatoms. Nitrogen stress serves as a key trigger for the dominance of nitrogen-fixing cyanobacteria, and adding N when cyanobacteria dominates shifts communities to another toxin producing cyanobacteria. Furthermore, the production of the cyanotoxin microcystin increased with higher N/P ratios, indicating a close relationship between toxin synthesis and nitrogen availability. This study advances our understanding of how nutrient thresholds influence the selection of dominant algal genera and microcystin production in large rivers.

Jingjing Li (Primary Presenter/Author), Tennessee Tech University, jingjingli@tntech.edu;

Dalton Tryba (Co-Presenter/Co-Author), Tennessee Tech University, dtryba42@tntech.edu;

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

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6/04/2024  |   16:30 - 16:45   |  Salon 5/6

PHYSIOLOGICAL AND GROWTH RATE RESPONSES OF TOXIC AND NON-TOXIC MICROCOLEUS (CYANOBACTERIA) SPECIES UNDER LABORATORY CULTURE CONDITIONS Benthic cyanobacterial proliferations are a growing environmental concern, but factors promoting growth and toxin production remain relatively unknown. Microcoleus is a mat-forming cyanobacterium in streams which produces anatoxin-a (ATX), a neurotoxin implicated in dog deaths globally. We isolated six unialgal, non-axenic Microcoleus strains from four streams in northern California, classified them based on metagenome data, and elucidated life history strategies in a controlled, laboratory setting. Two strains from a Microcoleus mats in the Eel River (ER6 and ER12) were non-toxic. The four toxigenic strains we isolated were >99% Average Nucleotide Identity similar to the Microcoleus anatoxicus Stancheva & Conklin from the Russian River, which produced only detectable dihydroanatoxin-a (dhATX) during the experiment. Microcoleus strain from Rock Creek (RC9) produced dhATX only, while two M. anatoxicus strains from the Klamath River watershed (SR16 and SR17) produced higher levels of ATX than dhATX. To test how toxin production by each strain changed over time, strains were grown in batch monocultures for 46 days in liquid BG11 medium and reached stationary phase developing surface mats by day 30, with exception for RC9. The toxin production reached its maximum at day 13 for strain SR17 and at days 19 and 26 for the rest of the strains. All strains displayed storage granules along the cross-cell walls, which decreased rapidly at day 15 in toxic strains only during the peak of the toxin production. Growth rates were assessed with toxin production and other physiological data to help understand trade-offs and energetic expense of toxin-production.

Sydney Brown (Primary Presenter/Author), George Mason University, sbrown88@gmu.edu;

Abeer Sohrab (Co-Presenter/Co-Author), University of Utah, u1370694@utah.edu;

Joanna Blaszczak (Co-Presenter/Co-Author), University of Nevada, Reno, jblaszczak@unr.edu;

R Christian Jones (Co-Presenter/Co-Author), George Mason University, rcjones@gmu.edu;

Emma Boyden (Co-Presenter/Co-Author), George Mason University, eboyden@gmu.edu;

Gregory Boyer (Co-Presenter/Co-Author), State University of New York College of Environmental Science and Forestry, glboyer@esf.edu;

Bofan Wei (Co-Presenter/Co-Author), State University of New York College of Environmental Science and Forestry, bwei101@syr.edu;

Robert Shriver (Co-Presenter/Co-Author), University of Nevada, Reno, rshriver@unr.edu;

Ramesh Goel (Co-Presenter/Co-Author), University of Utah, ram.goel@utah.edu;

Rosalina Stancheva Christova (Co-Presenter/Co-Author), George Mason University, rchris13@gmu.edu;

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6/04/2024  |   16:45 - 17:00   |  Salon 5/6

NUTRIENT STOICHIOMETRY PROMOTES CYANOBACTERIVORY WITHIN THE MICROBIAL FOOD WEB: IMPLICATIONS FOR CYANOBACTERIA TOXICITY Blooms of toxigenic cyanobacteria pose a mounting risk to aquatic ecosystems. Relative to abiotic drivers of cyanobacteria success, biotic processes, which may substantially influence nutrient cycling, have received less attention. Amongst the growing list of eukaryotes that can ingest and resist toxic cyanotoxins are mixotrophic nanoflagellates that combine heterotrophic ingestion of particulate prey with the capacity for photoautotrophy. We used laboratory experiments in batch culture to integrate top-down (grazing by heterotrophic and mixotrophic protists) and bottom-up (nutrient stoichiometry) controls on growth and production of microcystin-LR, including biodegradation products, of Microcystis by Ochromonas (mixotroph) and Spumella (heterotroph). A notable reduction in growth rate of toxic Microcystis, relative to monoculture, was evident in co-culture with both Ochromonas and Spumella under P-limitation. Under P-limitation, co-culture of toxic Microcystis with Ochromonas led to a significant reduction in concentration of MC-LR and increase in associated biodegradation products. Daily grazing rates up to 31 cells/day and 50 cells/day on the toxic strain were recorded for Ochromonas and Spumella, respectively. Collectively, these results suggest a role for eukaryotic nanoflagellates in decreasing the biomass and toxicity associated with cyanobacteria blooms under different stoichiometric nutrient conditions and highlight unresolved linkages within the microbial food web.

Sarah Princiotta (Primary Presenter/Author), Pennsylvania State University Schuylkill , sbp20@psu.edu;

Ted Harris (Co-Presenter/Co-Author), Kansas Biological Survey and Center for Ecological Research, ted.daniel.harris@gmail.com;

Dale Holen (Co-Presenter/Co-Author), Pennsylvania State University Scranton, dah13@psu.edu;

Josh Kellogg (Co-Presenter/Co-Author), Pennsylvania State University, jjk6146@psu.edu;

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