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SFS Annual Meeting

2021 Detailed Schedule

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Paula Furey (Primary Presenter/Author)
St. Catherine University,;

Jill Welter (Co-Presenter/Co-Author)
St. Catherine University,;

Abstract: In nitrogen-poor streams or under nitrogen-limiting conditions, algae and cyanobacteria that fix atmospheric nitrogen can have a competitive advantage over other taxa. However, as an energetically costly process, nitrogen fixation can be constrained by light availability and temperature levels. Environmental preferences of different N2-fixing species can further shape distribution patterns over time and space. The abundance and species composition of N2-fixing taxa, and their rates of N2-fixation can determine how, where, and under what conditions nitrogen enters the ecosystem and where it goes from there. From nitrogen-poor streams in Iceland and California, we compared N2-fixation rates for cyanobacteria (e.g., Anabaena, several Nostoc species, Rivularia) and Epithemia species (diatoms with cyanobacteria endosymbionts) under different light and temperature conditions. N2-fixation rates varied by genus and species, though light and temperature preferences complicated taxon-specific comparisons. N2-fixation rates generally increased with temperature but varied by taxon. Results highlighted areas needing further research. Knowledge of taxon-specific N2-fixation rates under varied environmental conditions will strengthen our ability to scale up predictions of nitrogen cycling and to predict biofilm response to our warming, nutrient-rich world.

Effects of thiamine and its precursor HMP on growth of periphyton in a mountain stream of the Yangtze River basin, China [Oral Presentation]

Binbin Wang (Primary Presenter/Author)
Cornell University,;

Clifford Kraft (Co-Presenter/Co-Author)
Cornell University,;

Abstract: We evaluated the ecological effects of thiamine and one of its precursors 2-methyl-4-amino-5-hydroxymethylpyrimidine (HMP) in Qiyun stream, a headwater mountain stream of a Yangtze River tributary in Southern China using nutrient diffusing substrates. Thiamine limitation and HMP limitation of periphyton were observed in April 2019, and co-limitation by thiamine/ HMP with nitrogen and phosphorus occurred in May 2019. The effect sizes of thiamine and HMP on growth of periphyton were similar to each other. However, physiochemical features of the stream showed different influences on the effects of thiamine and HMP. Water temperature, NH4+, and chlorophyll a concentrations in the stream water each negatively associated with HMP limitation; while soluble reactive phosphorus (SRP) and dissolved oxygen showed positive relationships with the effect of HMP. Light intensity was positively associated with thiamine limitation.


Kelsey Solomon (Primary Presenter/Author)
Odum School of Ecology, University of Georgia,;

Rebecca Bixby (Co-Presenter/Co-Author)
University of New Mexico,;

Seth Wenger (Co-Presenter/Co-Author)
Odum School of Ecology, University of Georgia,;

C. Rhett Jackson (Co-Presenter/Co-Author)
University of Georgia,;

Catherine Pringle (Co-Presenter/Co-Author)
University of Georgia,;

Abstract: Given the increase of tree species loss due to non-native pests, and the interconnectedness of terrestrial and stream ecosystems, there is a need for a greater understanding of the effects of riparian tree species loss on the structural characteristics of stream ecosystems. Our objectives were to assess potential changes in stream canopy cover, algal standing crop, and algal community composition in eight southern Appalachian headwater stream reaches thirteen years following the massive die-off of eastern hemlock (Tsuga canadensis) during both summer (September) and winter (January). Based on the expectation of increased canopy openness and light availability following hemlock death, we predicted to find higher algal standing crop and changes in algal community composition. However, post-hemlock die-off in 2018/2019, we found little change in canopy cover and significantly lower algal standing crops, likely due to increased basal area of the understory shrub, Rhododendron maximum. Algal community composition were dominated by acidophilic diatom taxa (e.g., Eunotia spp.) across all pre- and post-die off dates. Our study highlights the relative stability of algal communities in rhododendron-dominated southern Appalachian streams, and the importance of long-term studies following the invasion of a non-native pest.


Leon Katona (Primary Presenter/Author)
Wright State University ,;

Lyubov E. Burlakova (Co-Presenter/Co-Author)
Great Lakes Center at SUNY Buffalo State,;

Alexander Y. Karatayev (Co-Presenter/Co-Author)
Great Lakes Center at SUNY Buffalo State,;

Yvonne Vadeboncoeur (Co-Presenter/Co-Author)
Wright State University,;

Abstract: Assessments of benthic algae in large lakes are rare owing to difficulties in sampling an extensive, structurally heterogeneous habitat. The shells of invasive dreissenid mussels may provide novel hard surfaces in an expanse of otherwise soft sediments in the Great Lakes benthos. We measured the composition, biomass, and photosynthesis of algae growing on sediments and attached to dreissenid mussels across broad depth gradients during the Cooperative Science and Monitoring Initiative surveys in September 2018 (Lake Ontario; 46 sites) and July 2019 (Lake Erie; 43 sites). Sediment chlorophyll was greatest in shallow littoral waters and decreased with depth. We detected benthic photosynthesis from 10 – 40 m in both lakes. Sediments contained abundant mobile benthic diatoms but there were also many settled planktonic diatoms. Biofilms on Dreissena were composed of similar diatoms as sediments, but rarely contained planktonic taxa. Cyanobacteria (Pseudoanabaena, Phormidium) and green algae (Pediastrum) were more common on Dreissena than on sediments. The colonization of soft sediments by Dreissena is providing opportunities for filamentous algae to persist in previously unsuitable habitats throughout the Great Lakes, which could have profound ramifications for nutrient and energy flow in the littoral zone.


R. Jan Stevenson (Primary Presenter/Author)
Michigan State University,;

Abstract: Watershed groups for high quality lakes (TP less than 10 ug\L) in the northern region of Michigan’s lower peninsula have observed increases in thick, nuisance-level benthic diatom mats in the last 1-2 decades. Stakeholders and I developed a list of potential hypotheses for causes of what stakeholders call golden brown algae (GBA). Groundwater contamination by nutrients was deemed the most likely hypothesis, but we also consider many more. Spatial patterns in GBA are poorly related to land use and streams around lakes, as we would expect for groundwater or surface water contamination. However nearshore waters are enriched with P, which likely comes from P-enriched groundwater. Experiments and nutrient concentrations show that GBA growth is highly limited by low P supply, more than low N. GBA mats are dominated by diatom species adapted to the extremely low nutrient supply in control treatments of my experiment. In addition, historical diatom assemblages reported in regional paleolimnological studies indicate at least one low nutrient taxon was not listed. Therefore, incomplete and often contradictory results prevent identifying the causes of GBA with enough certainty to guide management. Studies continue to reach that goal.


Madeleine Malmfeldt (Primary Presenter/Author)
Brigham Young University,;

Abstract: Eutrophication, due to increases in nitrogen and phosphorus, poses a threat to water security locally and globally. To determine the nutrient thresholds that cause algal and cyanobacterial blooms in mesotrophic, deep-water, reservoirs, we performed 5- and 10-day nitrogen (N) and a phosphorus (P) starvation assays in 4-L microcosms from two dominant water reservoirs for the state of UT, USA (Deer Creek Reservoir and Jordanelle Reservoir). Nutrient starvation was induced by adding high levels of background N or P, followed by incremental increases in the nutrient of interest. For both reservoirs, using chlorophyll-a as in indicator for algal growth, we found that for both N and P there was a stepwise increase in algal biomass with increases in either nutrient addition, (N: 0-1 mg/L, P: 0-.08 mg/L), with no visible threshold or plateau to algal growth. A similar pattern was observed for the pigment phycocyanin, an indicator for cyanobacterial growth. The species of cyanobacteria participating in this growth are Anabaena sp, Aphanizomenon flos-aque, Chroococcus sp, Microcysitis sp, Lyngbia sp. Our results suggest potential increases in eutrophication in these reservoirs if future loads of either nitrogen or phosphorus increase.

Trait-based multimetric indices for diatom assessment of rivers and streams across the conterminous United States [Oral Presentation]

Ryan Hill (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

Alan Herlihy (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

David Peck (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

Philip Kaufmann (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

John Stoddard (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

Steven Paulsen (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

Luisa Riato (Primary Presenter/Author)
ORISE c/o US EPA, Pacific Ecological Systems Division, Corvallis, OR,;

Abstract: Taxonomic inconsistency in diatom datasets can constrain use of diatoms as biological indicators in rivers and streams assessments in the United States (US). For projects like the USEPA’s National Rivers and Streams Assessment (NRSA), differences in species identification or nomenclature among multiple taxonomy laboratories can render diatom data unusable in large-scale assessments. We address this problem by developing trait-based diatom multimetric indices (MMIs) to assess river and stream condition across the conterminous US, using a separate MMI for the East, Plains, and West ecoregions. Diatom data from the 2008-2009 NRSA were used to develop candidate metrics by assigning taxa to morphological and functional traits based on genus-level attributes. Other metrics were developed from diatom genera. The final trait-based MMI for the East had the greatest precision and ability to discriminate reference from disturbed sites, followed by MMIs for the Plains and West. MMI performances were comparable with NRSA MMIs for other biological assemblages for these ecoregions. Our work shows trait-based diatom indices are effective for large-scale assessments, and because they are less labor-intensive and more immune to taxonomic inconsistencies than species-based indices, they are also more practical and reliable.


Richard Lizotte (Primary Presenter/Author)

Jason Taylor (Co-Presenter/Co-Author)

Martin Locke (Co-Presenter/Co-Author)

Abstract: Eutrophication continues to impact freshwater ecosystems in agriculturally dominated watersheds throughout the world. Two agriculturally influenced watersheds with varying agricultural best management practices (BMPs), Roundaway Lake (acreage, 1.4% BMPs) and Beasley Lake (acreage, 17.1% BMPs) in western Mississippi, were studied monthly during the growing season to determine algal photosynthetic responses to nutrients. Long-term monitoring (9 years) indicate Roundaway is more eutrophic than Beasley. Pulse-amplitude-modulated (PAM) fluorometry was used to assess nutrient limitation and gradient responses for algal photosynthesis. Algal photosynthetic responses to nutrient gradients were determined using Michaelis-Menten regressions to obtain half-nutrient saturation constants (K). Algal PAM fluorometric responses were associated with algal growth rate (R2, 0.321-0.530). Phytoplankton photosynthesis showed primarily N+P limitation in both lakes with some N-only limitation or no limitation and only rare P limitation. Values for K varied widely: 0.039-1.771 mg TN/L and 0.010-0.423 mg TP/L. However, models indicated K was generally lower in Beasley than Roundaway indicating greater nutrient sensitivity in Beasley. Results indicate BMPs mitigating eutrophication can affect algal photosynthesis and that PAM fluorometry is a sensitive and useful tool for assessing algal photosynthesis nutrient limitation and sensitivity in eutrophic lakes.

Warm “winter” temperatures promote reservoir cyanobacterial dominance across enriched nutrient regimes [Oral Presentation]

Nicole Lindor (Primary Presenter/Author)
North Carolina State University,;

JoAnn Burkholder (Co-Presenter/Co-Author)
North Carolina State University,;

Abstract: Shifting nutrient regimes characterize many potable source-water reservoirs worldwide, concomitant with global warming. In a southeastern U.S. reservoir, we experimentally assessed short-term in situ phytoplankton assemblage response to three inorganic nitrogen-to-phosphorus (Ni/Pi) ratios in an average cold winter versus a warm winter (mean water temperatures 7C and 10C, respectively). Ratios were imposed with Ni as ammonium or nitrate +/- Pi (phosphate): 32N:1P (ambient P); elevated, 50N:1P (ambient P); and enriched Redfield, 16N:1P (both nutrients added). In the average cold winter, diatoms comprised up to 70% of the total phytoplankton cells, followed by chlorophytes. Diatoms remained dominant, increasing under nitrate enrichment +/-Pi, in the elevated and enriched Redfield treatments. In the warm winter, diatoms and chlorophytes initially dominated the assemblages (up to 40% and 20%, respectively). Cyanobacteria more than doubled in controls and all treatments as diatoms were reduced under ammonium enrichment. While cyanobacteria were stimulated in all ratios, the greatest stimulation was in the enriched Redfield treatment under ammonium+Pi. The findings suggest that the combination of warming winters and increasing ammonium+Pi enrichment will promote the loss of freshwater winter/early spring diatom blooms in favor of cyanobacteria as cultural eutrophication progresses.


Nayeli K. Sanchez (Primary Presenter/Author)
The Ohio State University,;

S. Mažeika P. Sullivan (Co-Presenter/Co-Author)
The Ohio State University,;

Carlos Cáceres (Co-Presenter/Co-Author)
The Ohio State University,;

Abstract: Land use and their associated environmental stressors and land use strongly influence water quality in stream networks, however, their contributions to riverine algal blooms requires further research. In this study, we examine the influence of nutrient stoichiometry and multiple environmental stressors such as physical channel alterations and temperature regimes as drivers of phytoplankton and benthic algae community composition in streams and reservoirs. From 2016-2020, we measured physicochemical water-quality parameters, nitrogen and phosphorus concentrations, continuous temperature, and fluvial geomorphic characteristics in streams and reservoirs throughout seven watersheds of agricultural, mixed, and forested land uses in Ohio, Kentucky, Indiana and Tennessee. We also assessed the relative contributions of four major algal classes on total phytoplankton and benthic algae biomass at each study site and determined microcystin concentrations using SPATT (Solid Phase Adsorption Toxin Tracking) samplers. In phytoplankton, mean chlorophyll a from cyanobacteria was 11.7 ± 25.4 µg L-1, 6.5 ± 16.6 µg L-1, and 2.0 ± 4.3 µg L-1 in agricultural, mixed, and forested catchments, respectively. Our findings will contribute to the understanding of riverine algal community structure and the development of classification systems for predicting harmful algal blooms (HABs).


Shannon Weld (Primary Presenter/Author)
University of New Mexico,;

Debra Finn (Co-Presenter/Co-Author)
Missouri State University,;

Lusha Tronstad (Co-Presenter/Co-Author)
University of Wyoming, Wyoming Natural Diversity Database,;

Scott Hotaling (Co-Presenter/Co-Author)
Washington State University,;

Rebecca Bixby (Co-Presenter/Co-Author)
University of New Mexico,;

Abstract: Climate change poses a threat to alpine streams and their algal communities. Hydrologic sources like snowpack, surface glaciers, and rock glaciers are all at risk due to warming temperatures. We characterized algal communities among alpine streams from these sources in the Teton Range, Wyoming, USA. In August 2019, three snowmelt-fed, three surface glacier-fed, and four rock glacier-fed streams were sampled for periphytic algae, anions, cations, and water quality parameters. Rock glacier-fed streams consistently had the lowest water temperature and highest pH and conductivity. Rock glacier-fed streams also had the highest calcium, magnesium, and potassium concentrations, while nitrate and sulfate concentrations were higher in surface glacier-fed streams. Surface glacier-fed and rock glacier-fed streams had lower algal biomass than snowmelt-fed streams. Communities in snowmelt-fed and surface glacier-fed streams were more diverse, including diatoms Hannaea arcus, Odontidium mesodon, and Encyonema spp. that are characteristic of western mountain streams. Rock glacier streams were dominated by upright forms indicative of stable flows, including Gomphonema spp. These are valuable baseline data describing little-known algal communities of alpine streams representing a heterogeneity of hydrologic sources and will be vital to monitoring change as the climate warms.


Gretchen Rollwagen-Bollens (Co-Presenter/Co-Author)
Washington State University,;

Stephanie Hampton (Co-Presenter/Co-Author)
Washington State University,;

Kathryn Sweeney (Primary Presenter/Author)
Washington State University,;

Abstract: Vancouver Lake in western Washington is one of many freshwater lakes characterized by annual cyanobacteria blooms, which often produce harmful toxins. Zooplankton grazers consume cyanobacteria and other phytoplankton thereby influencing and possibly controlling, harmful bloom dynamics. Previous studies have shown copepod grazing to contribute to bloom formation in many lakes, including Vancouver Lake, but bloom decline to be largely driven by microzooplankton community (i.e., rotifers, ciliates, dinoflagellates) grazing. While the trophic role of some microzooplankton have been investigated, little is known about the influence of rotifer grazing on cyanobacteria. Therefore, experiments with field-collected rotifers grazing upon a natural assemblage of phytoplankton from Vancouver Lake were performed from June through October 2019, capturing the conditions at each stage of a large cyanobacteria bloom. Preliminary results show that rotifers had a small but significant grazing impact on cyanobacteria and other phytoplankton, especially after the peak of the bloom. Additionally, we found the entire microzooplankton community had a large impact on phytoplankton biomass both before and after the bloom peak. These findings suggest that non-rotifer microzooplankton (i.e., ciliates or dinoflagellates) may be mostly responsible for suppressing cyanobacteria blooms.

Harmful cyanobacterial bloom (HCB) dynamics in Wyoming reservoirs [Poster Presentation]

William Fetzer (Co-Presenter/Co-Author)
University of Wyoming,;

Annika Walters (Co-Presenter/Co-Author)
USGS Wyoming Coop Fish and Wildlife Unit,;

Matthew Ross (Co-Presenter/Co-Author)
Colorado State University,;

Lindsay Patterson (Co-Presenter/Co-Author)
Wyoming Department of Environmental Quality,;

Michael Thomas (Co-Presenter/Co-Author)
Wyoming Department of Environmental Quality,;

Sarah Collins (Co-Presenter/Co-Author)
University of Wyoming,;

Sam Sillen (Primary Presenter/Author)
University of Wyoming,;

Abstract: Harmful cyanobacterial blooms (HCBs) are a growing concern among resource managers due to detrimental effects to ecosystem function, recreation, and drinking water sources. In Wyoming, the awareness and frequency of blooms has increased in recent years with over 20 advisories in 2020. Previous studies have identified climate and nutrient loading as factors that can encourage blooms, however drivers of HCBs are understudied across Wyoming's unique hydrological regimes and landscape features. To address this knowledge gap, we used satellite imagery and climate data to identify how climate and watershed characteristics make waterbodies susceptible to HCBs. We obtained cyanobacteria abundance and chlorophyll-a estimates from Sentinel-3 satellite images for 40 lakes in Wyoming. These estimates will be paired with climate and land use data from the LAGOS (Lake Multi-Scaled Geospatial and Temporal database) dataset to predict how climate and watershed characteristics drive blooms. This project will increase understanding of historical trends in HCBs and their drivers in Wyoming, helping to inform management actions that address their frequency and intensity.

Medium- term distribution of the micro-phytoplankton functional groups in a temperate shallow urban lagoon (Gualeguaychú, Argentina) [Poster Presentation]

Diamela Gianello (Primary Presenter/Author,Co-Presenter/Co-Author)
Laboratorio de Indicadores Biológicos y Gestión Ambiental de Calidad de Agua (IBGA), Facultad de Ciencia y Tecnología de la Universidad Autónoma de Entre Ríos (FCyT-UADER); Instituto de Investigaciones en Biodiversidad y Medioambiente (Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional del Comahue) - Laboratorio de Indicadores Biológicos y Gestión Ambiental de Calidad de Agua (IBGA), Facultad de Ciencia y Tecnología de la Universidad Autónoma de Entre Ríos (FCyT-UADER), ;

Melina Celeste Crettaz Minaglia (Co-Presenter/Co-Author)
Laboratorio de Indicadores Biológicos y Gestión Ambiental de Calidad de Agua (IBGA), Facultad de Ciencia y Tecnología de la Universidad Autónoma de Entre Ríos (FCyT-UADER),;

Abstract: Functional groups (FGs) classification based on individual traits of phytoplankton and the environmental conditions has been increasingly applied as a bioindicator tool. From May-2015 to August-2019, 25 micro-phytoplankton (MP) sampling were carried out in the lagoon of Parque Unzué using a net (pore= 30 µm) in 3 sampling stations (n=75). MP was identified down to the lowest taxonomic level, and classified into FGs. Forty-nine genera were identified distributing in 6 taxonomic groups: Chlorophyceae (15), Bacillariophyceae (9), Euglenophyceae (5), Cyanophyceae (6), Zygnemataceae (2), and Dinophyceae (2). Of the total of the genera, 37 were classified on 20 FGs being the more frequent W1 , J, MP, and P, characteristic of small water bodies, nutrient-rich, and high turbidity. Although its appearance was not frequent, Ceratium (FG = LM), an invasive genus in freshwaters of South America, was recorded in the autumn-2015 and winter-2019 samples. Moreover, no significant differences (p> 0.05) were found between sampling stations, while differences were found between sampling years and climatic seasons. MP and FGs were an important tool that provided easy, low-cost, and fast information on the status of the lagoon on which information was not previously available.


KathiJo Jankowski (Co-Presenter/Co-Author)
U.S. Geological Survey, Upper Midwest Environmental Sciences Center, ;

Jessica Fulgoni (Co-Presenter/Co-Author)
Missouri Department of Conservation,;

Douglas Baumann (Co-Presenter/Co-Author)
The University of Wisconsin - La Crosse,;

Barbara Bennie (Co-Presenter/Co-Author)
The University of Wisconsin - La Crosse,;

Molly Van Appledorn (Co-Presenter/Co-Author)
U.S. Geological Survey, Upper Midwest Environmental Sciences Center,;

James Pack (Primary Presenter/Author)
Centre College,;

Lamia Benyamine (Co-Presenter/Co-Author)
University of Central Florida,;

Abstract: Phytoplankton serve as the basis of aquatic food webs, providing a food source for larger organisms and aiding in nutrient processing. However, eutrophication promotes the formation of harmful algal blooms, some of which have recently occurred in large rivers in the Midwestern United States. Few studies exist on river phytoplankton communities, including the Upper Mississippi River System (UMRS). Therefore, our main objectives were to characterize the community of phytoplankton across over 1500km of the UMRS and understand their response to environmental factors. Community and environmental data collected from six river reaches during the spring and summer of 1996-2012 were evaluated. Communities in the northern reaches were more diverse and distinct from the southern reaches. Cyanobacteria made up ~15% of the communities in the northern reaches but were nearly absent from other reaches. Additionally, community composition was significantly different among reaches and was most strongly related to the nitrogen to phosphorus ratio. These relationships increase our understanding of riverine phytoplankton communities, including environmental factors that promote cyanobacteria presence, which helps inform the management of the UMRS to reduce the risk of harmful species.