SFS Annual Meeting

6/03/2024  |   13:45 - 14:00   |  Salon 10

GREAT CLARITY, LESS FILLING? ASSESSING THE INTERPLAY OF CLARITY AND WATER LEVEL IN NINE LAKES IN NORTHWEST WISCONSIN Water levels in lakes fluctuate primarily because of variation in precipitation and evaporation from season to season and year to year. Precipitation events flush inorganic and organic material from the watershed into lakes. Therefore, as water levels increase, clarity should decrease due to the influx of sediment, tannins, and other compounds. We explored the relationship of lake levels, water clarity, and algal abundance in nine Northwest Wisconsin lakes. The lakes varied in morphometry, dissolved organic matter concentrations, and mixing regime (e.g., dimictic, polymictic), but experienced comparable precipitation given their relative proximity on the landscape. We assessed the relationship of water level and clarity by comparing stage height to light attenuation, which was recorded multiple times annually across five to nine years. The nine lakes varied in their degree of water level fluctuations across the study period. As predicted, clarity was lower during periods of higher water levels. However, the degree to which clarity fluctuated was influenced by the relative clarity of the lake. For example, a clear-water lake in our study experienced a small change in light attenuation while the water level fluctuated 1.1 meters (slope = 0.1). In contrast, light attenuation varied more in a stained brown-water lake as the lake fluctuated 0.8 meters (slope = 0.6). The coincident changes in lake level and clarity have ripple effects on freshwater habitat quality and food webs. The results of our study can inform lake management decisions, which may need to be adapted as lake levels change through time.

Peter S. Levi (Primary Presenter/Author), Burke Center, Northland College, plevi@northland.edu;

Cayla M. Cavey (Co-Presenter/Co-Author), Burke Center, Northland College, ccavey@northland.edu;

Matthew J. Hudson (Co-Presenter/Co-Author), Burke Center, Northland College, mhudson@northland.edu;

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6/03/2024  |   14:00 - 14:15   |  Salon 10

Do scattered trees affect tadpole communities and nutrient recycling in small Brazilian ponds? Amphibians have a biphasic life cycle, relying on both aquatic and terrestrial habitats, but deforestation and land-use change can disrupt the connection between these ecosystems. Scattered trees are keystone structures in human-modified landscapes, provisioning microclimate, habitat, and maintaining connectivity by acting as stepping stones. Our objective is to understand how landscape elements, especially scattered trees, affect pond ecosystem structure, tadpole communities and tadpole contribution to nutrient dynamics. We used experimental ponds in Brazil, located in a pasture grassland surrounded by forest fragments divided into 3 treatments: 4 ponds at the edge of a forest fragment, 5 ponds under a scattered tree and 4 ponds in open pasture. In each pond, we measured biotic and abiotic variables, tadpole abundance and community composition, and tadpole nutrient excretion rates. Scattered-tree ponds tended to have higher dissolved nutrients, chlorophyll-a concentration, and allochthonous material, while pasture ponds tended to have higher turbidity, oxygen and lower conductivity. Sixteen tadpole species used our experimental ponds for breeding. Landscape elements and biotic and abiotic pond characteristics had no effect on tadpole abundance. Scattered-tree ponds presented lower species richness and diversity than edge ponds and pasture ponds. These patterns were not reflected on tadpole nutrient contribution to the ecosystem, as there was no effect of landscape elements on tadpole community areal excretion. However, species richness and diversity were important predictors of community areal excretion. This is one of the first studies investigating how landscape characteristics affect ecosystem structure in small tropical ponds and how amphibians mediate ecosystem functions.

Eugenia Zandona (Primary Presenter/Author), Universidade do Estado do Rio de Janeiro, eugenia.zandona@gmail.com;

Beatriz Moreira-Ferreira (Co-Presenter/Co-Author), UNIVERSIDADE DO ESTADO DO RIO DE JANEIRO, biaferreira.biologia@gmail.com;

João Luiz de Caires Souza (Co-Presenter/Co-Author), UNIVERSIDADE DO ESTADO DO RIO DE JANEIRO, joaosouzaaa10@gmail.com;

Vinicius Neres-Lima (Co-Presenter/Co-Author), Universidade do Estado do Rio de Janeiro, vinicius.lima.eco@gmail.com;

Jayme Prevedello (Co-Presenter/Co-Author), UNIVERSIDADE DO ESTADO DO RIO DE JANEIRO, ja_prevedello@yahoo.com.br;

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6/03/2024  |   14:15 - 14:30   |  Salon 10

FIRE ASH TEMPORARILY REVERSES THE CARBON SOURCE-SINK STATUS OF WETLAND MESOCOSMS The direct effects of fires on burned terrestrial ecosystems are relatively well studied, but there is comparatively little research on the effects of fires on adjacent aquatic systems. Fires can mobilize large quantities of black and white ash over great distances before they are deposited in streams and water bodies. We designed a laboratory mesocosm experiment to investigate the effects of these two ash types on water chemistry and carbon fluxes in wetland sediments. Black and white ash were produced from wood in a combustion oven at 300 and 600 degrees, respectively, and added to wetland mesocosms in varying concentrations and mixtures. Dissolved oxygen concentrations and pH decreased significantly after the addition of black ash, but white ash addition significantly elevated pH in mesocosms, likely due to high concentrations of cationic carbonates and oxides. Over the eight-day sampling period, black ash enhanced CO2 release from sediments, but white ash temporarily converted mesocosms into CO2 sinks. Both ash treatments significantly enhanced CH4 flux despite pH rising as high as 10.74 in white ash mesocosms, a value well above the optimal range for methanogenesis. Substantial benthic invertebrate mortality was not observed, and midges and oligochaetes appeared to be active in all mesocosms throughout the study. While there is still much to explore, these findings suggest that fires may temporarily alter the carbon source-sink status of recipient lentic aquatic ecosystems.

Nathan Earl (Primary Presenter/Author), University of Louisville, noearl01@louisville.edu;

Andrew Mehring (Co-Presenter/Co-Author), University of Louisville, a0mehr03@louisville.edu;

Jeroen de Klein (Co-Presenter/Co-Author), Wageningen University, jeroen.deklein@wur.nl;

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6/03/2024  |   14:30 - 14:45   |  Salon 10

Terrestrial and Aquatic Fungi: Similar Players, Different Behaviors This study examines how fungal succession on decomposing litter differs between terrestrial and aquatic environments. We hypothesize aquatic fungal communities to have distinct taxa from terrestrial communities, and a higher growth rate than terrestrial communities. We used quantitative stable isotope probing (qSIP) to examine changes in taxon-specific relative growth rates between fungi living on terrestrial and aquatic litter. With qSIP we can isotopically label new DNA and calculate relative growth rates for microbes down to the ASV level. We used two leaf types, over three timepoints, to capture changes in fungal activity between leaf litter on a river bank versus submerged leaf litter. Contrary to our predictions, 37% of active fungi are shared between terrestrial and aquatic litter. Relative growth rates between fungi living on land and in the water were similar at earlier harvests, but diverged through time as growth rates increased in terrestrial litter. The proportion of active taxa soon after leaf fall was similar for both habitats (69% for aquatic, and 63% for terrestrial), but increased in terrestrial litter over time, while slightly decreasing in aquatic litter. This study shows that a large proportion of fungi are active in both aquatic and terrestrial decomposition. Such comparisons give us unique insight into the life histories of fungal decomposers.

Helen Ochs (Primary Presenter/Author), Northern Arizon University, hco9@nau.edu;

Michaela Hayer (Co-Presenter/Co-Author), Northern Arizona University, michaela.hayer@nau.edu;

Egbert Schwartz (Co-Presenter/Co-Author), Northern Arizona University, egbert.schwartz@nau.edu;

Bruce Hungate (Co-Presenter/Co-Author), Northern Arizona University, bruce.hungate@nau.edu;

Jane Marks (Co-Presenter/Co-Author), Northern Arizona University, jane.marks@nau.edu;

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6/03/2024  |   14:45 - 15:00   |  Salon 10

RIPARIAN RAIN: FACTORS INFLUENCING THE MOVEMENT OF WATER, BROMIDE, AND NITROGEN Riparian zones act as buffer regions that absorb and retain excess nutrients and sediments from surface runoff, which helps maintain the water quality of streams. We conducted five rainfall simulation experiments over different slopes, soil types, and vegetation covers along a tallgrass prairie stream. We simulated strong rainstorms on strips 3 m wide and 6.1-10.0 m perpendicular to the stream. Between 5-15 cm of simulated rain fell in each experiment and the simulated storms lasted between 32 and 54 minutes. We used deionized water containing bromide (Br-) and 15N-nitrate to trace the movement of inert and biologically active molecules caused by rain falling immediately adjacent to the streams. Br- entered the stream in four experiments, with average velocities of flow across the surface ranging from 0 to 0.39 cm/s. When Br- entered the stream, we recovered about 10% of the mass added. The remainder was retained in the soil or shallow groundwater. Br- did not enter the stream in one experiment which included dense vegetation cover and a shallow slope. Nitrate is biologically active and proportionately less entered the stream as a function of soil and vegetative properties, including microbial and plant uptake.

Madison Moriello (Primary Presenter/Author), Kansas State University, moriello@ksu.edu;

Brooke Burris (Co-Presenter/Co-Author), Kansas State University, blburris@ksu.edu;

Abu Raihan (Co-Presenter/Co-Author), Kansas State University, aburaihan@ksu.edu;

Walter Dodds (Co-Presenter/Co-Author), Kansas State University, wkdodds@ksu.edu;

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