SFS Annual Meeting

5/24/2018  |   09:00 - 09:15   |  321

DETRITUS AND EUTROPHICATION OF STREAMS Detritus is a key carbon input into freshwaters, and the idea of heterotrophic and autotrophic state more clearly represents ecosystem structure than a view centered solely on autotrophic. Maintaining biotic integrity and biodiversity is one regulatory goal in freshwaters. A long-time key endpoint for carbon inputs has been maintaining dissolved oxygen by limiting inputs of biochemical oxygen demand. Detrital endpoints for inorganic nutrient pollution are less clear as biotic integrity and ecosystem respiration rates are more variable. Substantial data are accruing that indicate that both N and P additions can alter the heterotrophic state, the food web that depends upon detritus, diversity, and central ecosystem functions such as carbon sequestration. Additionally, bioassays indicate that heterotrophic activity can be stimulated by nutrients in streams across the US. Analysis of a large data set on Midwestern US nutrients and stream invertebrates shows that shredder diversity is dependent upon total P with high diversity at low total P levels. These levels are in line with reference nutrient estimates for these ecoregions.

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


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5/24/2018  |   09:15 - 09:30   |  321

NUTRIENT-STIMULATED DETRITAL LOSS RATES FROM LITTERBAGS ARE PREDICTIVE OF LOSSES AT STREAM REACH SCALES Excess nutrients increase detrital loss rates in streams, resulting in less carbon (C) for consumers and for functions such as uptake of pollutants. Our long-term experimental nutrient additions increased C loss rates from streams across nutrient concentrations and ratios. To evaluate the use of litterbag studies as indicators of nitrogen (N) and phosphorus (P) effects on stream-reach C loss, we compared breakdown rates (k) from litterbags with stream-reach loss rates. Stream-reach loss rates were best correlated with the lowest quality litter (e.g., R2 = 0.6), but medium quality was closer to the 1:1 line of stream-reach:litterbag rates, consistent with mixed litter composition in whole streams. At both scales, we found significant effects of both N and P, with P effects consistently greater (1.4-2.0?) than N effects based on standardized parameter estimates. Our studies provide support for the use of litterbag studies in predicting the effects of N and P enrichment on larger-scale C loss processes. Our results also suggest that low-quality litter species may be most sensitive in their responses to added nutrients, capture stream-reach loss dynamics most precisely, and thus may be most useful in monitoring and management applications

David W.P. Manning (Co-Presenter/Co-Author), University of Georgia, manningd@uga.edu;


Phillip Bumpers (Co-Presenter/Co-Author), University of Georgia, bumpersp@gmail.com;


John S. Kominoski (Co-Presenter/Co-Author), Florida International University, jkominoski@gmail.com;


Vlad Gulis (Co-Presenter/Co-Author), Coastal Carolina University, vgulis@coastal.edu;


Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama, jbenstead@ua.edu;


Amy D. Rosemond (Primary Presenter/Author), University of Georgia, rosemond@uga.edu;


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5/24/2018  |   09:30 - 09:45   |  321

FUNCTIONAL STABILITY DESPITE ADVERSE STRUCTURAL EFFECTS – A POTENTIAL HURDLE FOR THE USE OF LEAF LITTER DECOMPOSITION IN BIOMONITORING? The paramount importance of leaf decomposition for energy provisioning in heterotrophic aquatic food webs suggests its use as functional variable informing biomonitoring in anthropogenically impacted systems. Potential adaptation of decomposer communities to and recovery from stress with regards to their functional performance, however, may compromise the use of leaf decomposition by masking adverse structural effects. To test for this assumption, we quantified the effects of fungicides and nutrients (four levels each) on the structural and functional plasticity of leaf-associated decomposer communities with differing exposure histories (pristine vs. pre-exposed) over 21 d. Microbial leaf decomposition (MLD) was quantified as functional response, whereas fungal community composition and species richness characterized structural changes. MLD by pristine microbes was reduced by up to 30% with increasing fungicide levels, whereas the pre-exposed microbes augmented MLD by up to 85% upon fungicide exposure. A pollution-induced community tolerance, supporting the dominance of few species with high breakdown efficacies, may explain the maintained functioning under stress. In support of our initial assumption, these findings question at least an easy-to-interpret outcome of the data when leaf decomposition is used for biomonitoring without simultaneous characterization of structural changes.

Alexander Feckler (Primary Presenter/Author), Swedish University of Agricultural Sciences, alexander.feckler@slu.se;


Rebecca Bundschuh (Co-Presenter/Co-Author), University of Koblenz-Landau, bundschuh-r@uni-landau.de;


Marco Konschak (Co-Presenter/Co-Author), University of Koblenz-Landau, konschak@uni-landau.de;


Ralf Schulz (Co-Presenter/Co-Author), University of Koblenz-Landau, schulz@uni-landau.de;


Jochen Zubrod (Co-Presenter/Co-Author), University of Koblenz-Landau, zubrod@uni-landau.de;


Mirco Bundschuh (Co-Presenter/Co-Author), Swedish University of Agricultural Sciences, mirco.bundschuh@slu.se;


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5/24/2018  |   09:45 - 10:00   |  321

INCORPORATING FOOD WEBS INTO BIOASSESSMENT USING METABARCODING AND TEXT MINING: DO DERIVED NETWORK METRICS REFLECT ECOSYSTEM FUNCTION? Wetlands harbor a disproportionate amount of biodiversity and provide essential ecosystem services, yet 64-71% of global wetlands have disappeared since the 1900s. Given these ongoing threats, we require improved tools for wetland functional assessment to support effective management. Food web analysis is a powerful, under-utilized tool in ecosystem management. Using DNA metabarcoding to characterize aquatic communities can provide a standardized, sensitive method for rapid species detection and community assessment, but it does not yield requisite trait information for food web construction. Text-mining facilitates this, allowing trait data to be gathered for specific taxa across large databases. We combined DNA metabarcoding with text mining to create heuristic food webs for the Grand Lake Meadows, Atlantic Canada's largest freshwater wetland complex. We asked: (1) how do food web properties correlate with litter decomposition, (2) how do food web properties compare to traditional community metrics at predicting litter decomposition, and (3) do DNA-based food webs detect changes in structural-functional relationships across wetland protection levels? We explore how food webs, DNA, and decomposition could be integrated into future wetland assessments, elucidating relationships between biodiversity and ecosystem function.

Zacchaeus Compson (Primary Presenter/Author), University of North Texas, zacchaeus.compson@unt.edu;


Wendy Monk (Co-Presenter/Co-Author), Environment and Climate Change Canada @ Canadian Rivers Institute, Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, NB, Canada, wmonk@unb.ca;


Natalie Rideout (Co-Presenter/Co-Author), Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, NB, Canada, nrideout@unb.ca;


Christoper Baker (Co-Presenter/Co-Author), University of New Brunswick, bakerc@unb.ca;


Mohammad Sadnan Al-Manir (Co-Presenter/Co-Author), University of New Brunswick, sadnan.almanir@unb.ca;


Sonja Stefani (Co-Presenter/Co-Author), Dresden University of Technology, Institute of Hydrobiology, Dresden, Saxony, Germany, stefani.sonja@googlemail.com;


Mehrdad Hajibabaei (Co-Presenter/Co-Author), Centre for Biodiversity Genomics & Department of Integrative Biology, University of Guelph, ON, Canada, mhajibab@uoguelph.ca;


Donald Baird (Co-Presenter/Co-Author), Environment and Climate Change Canada @ Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, NB, Canada, djbaird@unb.ca;


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5/24/2018  |   10:00 - 10:15   |  321

MANAGING STREAMS FROM THE OUTSIDE IN Environmental regulation tends to focus on structural metrics of ecosystem integrity, which are not always sensitive to stream and riparian alterations. Functional metrics, such as the flow of carbon and nitrogen through the food web, likely paint a better picture of what is occurring in the stream and can be more sensitive to stream degradation. Here, we present a novel technique, using leaf litter enriched with ¹³C and ¹⁵N to trace the pathways of carbon and nitrogen transfer through stream food webs. Our results show that litter species influences the amount and timing of carbon and nitrogen assimilation by invertebrates. Some litter species contribute relatively more energy to microbial pathways, whereas others fuel macroscopic food webs. We demonstrate how alterations to stream and riparian condition influence the pathways of carbon and nitrogen flow through the food web and how these pathways may be more sensitive to degradation than conventional structural metrics of stream assessment. Our data highlight the need for a diversity of litter species to provide carbon and nitrogen resources for invertebrates throughout their life cycles.

Adam Siders (Primary Presenter/Author), University of Florida, asiders@ufl.edu;


Zacchaeus Compson (Co-Presenter/Co-Author), University of North Texas, zacchaeus.compson@unt.edu;


Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire, adam.wymore@unh.edu;
Dr. Adam Wymore is a Research Assistant Professor at University of New Hampshire.

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


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5/24/2018  |   10:15 - 10:30   |  321

LEAF DISK RESPIRATION AND ALKALINE PHOSPHATASE ACTIVITY MEASURED ACROSS A DISSOLVED INORGANIC PHOSPHORUS GRADIENT IN THE LABORATORY The strong statistical relationships between stream nutrient concentrations and litter decomposition and stoichiometry suggest they could be good detrital indicators of nutrient limitation and enrichment. Litter alkaline phosphatase activity (APA) and respiration may also be good indicators that could be measured more economically. We conducted a 210-d laboratory experiment to 1) examine the effects of time, litter type, and dissolved inorganic phosphorus (DIP)-enrichment on respiration rates and APA and to 2) determine whether these short-term measures were related to litter stoichiometry and decomposition rates. The APA did not depend on litter type, but did decline with increasing DIP on some sample days. Although time, litter type, and DIP all interacted to affect respiration few consistent trends were found beyond greater rates on maple compared to oak. Litter C:P declined predictably with DIP and was related to decomposition indicating P-limitation, but APA was only sometimes positively correlated with litter C:P. Therefore, litter APA was not a consistent indicator of P-limitation of decomposition. Decomposition and respiration rates were positively correlated for both litter types, but the amount of variation explained was relatively low suggesting additional work establishing this possible indicator is needed.

Michelle Evans-White (Primary Presenter/Author), University of Arkansas, mevanswh@uark.edu;


Ayla Smartt (Co-Presenter/Co-Author), University of Arkansas, asmartt@uark.edu;


Sally Entrekin (Co-Presenter/Co-Author), Virginia Tech, sallye@vt.edu;


Halvor Halvorson (Co-Presenter/Co-Author), University of Central Arkansas, hhalvorson@uca.edu;


Thad Scott (Co-Presenter/Co-Author), Baylor University, Thad_Scott@baylor.edu ;


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