SFS Annual Meeting

5/23/2019  |   09:00 - 09:15   |  254 B

A FIELD BASED EXPERIMENT ON THE RESPONSES OF DIFFERENT MICROBIAL COMMUNITIES AND RELATED ECOSYSTEM FUNCTIONS TO FUNGICIDES In viticulture, fungicides are the predominant pesticide group and are known to affect stream microbial communities, particularly the hyphomycete fungi. These play a key role in the decomposition of allochthonous material. Previous studies showed that hyphomycete communities and its decomposition are altered along fungicide gradients. In this study, we focused on the community and ecosystem function responses to fungicides using three hyphomycete community treatments on leaves in ten streams in an intensive vinicultural region of South-West Germany. The first treatment represented an undisturbed control in a forested upstream area. The second treatment represented a viticulture treatment in the downstream vinicultural area. The third treatment represented a transplantation treatment where the leaves were colonised by hyphomycete communities in the forested upstream area and subsequently transplanted to the downstream vinicultural area. We analysed the community composition and microbial leaf decomposition of the three treatments at four different time points, capturing the time before, within and after fungicide application. We discuss the community and ecosystem function responses to fungicides and potential mechanisms.

Verena C. Schreiner (Primary Presenter/Author), University of Koblenz-Landau, Institute for Environmental Sciences, schreiner-verena@uni-landau.de;


Moritz Link (Co-Presenter/Co-Author), University of Koblenz-Landau, Institute for Environmental Sciences, link@uni-landau.de;


Gesa Amelung (Co-Presenter/Co-Author), University of Koblenz-Landau, Institute for Environmental Sciences, amel7631@uni-landau.de;


Ralf Schäfer (Co-Presenter/Co-Author), University of Koblenz-Landau, Institute for Environmental Sciences, schaefer-ralf@uni-landau.de;


Presentation:
This presentation has not yet been uploaded.

5/23/2019  |   09:15 - 09:30   |  254 B

TEMPERATURE VARIANCE LEADS TO UNDERESTIMATION OF THE TEMPERATURE SENSITIVITY OF PLANT LITTER DECOMPOSITION Temperature sensitivity of plant litter decomposition is critical to estimate, as temperature increases will accelerate losses of plant carbon to CO2. A common approach to assess temperature x decomposition relationships uses spatial gradients in temperature to estimate activation energies (Ea). These estimates relate decomposition rates to average temperatures across sites, ignoring within-site temperature variance. We hypothesized that temperature variance can increase decomposition and affect predictions of temperature sensitivity. We tested this by simulating plant litter decomposition in terrestrial and aquatic environments with global and U.S. temperature datasets and explored patterns in temperature means and variance. We found that variance is typically higher at cooler mean temperatures, particularly in terrestrial datasets. Estimates of temperature sensitivity (apparent Ea) made from data simulated with real time series of temperature and known temperature sensitivity (inherent Ea) showed that variance in temperature could bias estimates of Ea by up to 0.3 eV. Our results suggest that commonly used methods may underestimate the temperature dependence of litter decomposition, particularly in terrestrial environments. Thus, we encourage assessment of temperature mean and variance relationships when estimating activation energies to improve predictions of future carbon loss.

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


Carolyn Cummins (Co-Presenter/Co-Author), The University of Georgia, carolynsc1225@gmail.com;


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


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


Seth Wenger (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, swenger@uga.edu;


Nathan Tomczyk (Primary Presenter/Author), University of Georgia, nathan.tomczyk@gmail.com;


Presentation:
This presentation has not yet been uploaded.

5/23/2019  |   09:30 - 09:45   |  254 B

UNDERSTANDING THE ENVIRONMENTAL CONTEXT OF ALGAL PRIMING OF COARSE PARTICULATE ORGANIC MATTER DECOMPOSITION IN STREAMS Streams can obtain energy from two main sources: autochthonous organic matter or allochthonous inputs of organic matter. Interactions between organisms involved in these two types of energy acquisition exist within microcommunities of algae, fungi, and bacteria that form on inert and organic substrata. Previous experiments have observed interactions between photosynthetic and heterotrophic organisms within biofilms through algal priming. The release of a labile carbon source by algae may stimulate the decomposition of coarse particulate organic matter by heterotrophic organisms. To better understand algal priming, we evaluated the environmental factors that may influence the process. Cotton strips were placed in either darkened and transparent tubes and anchored to the bottom of 18 streams of varying stream order and nutrient content. The cotton strips were then evaluated for algal biomass and tensile strength to quantify decomposition. Cotton strips with higher algal biomass appeared to have low tensile strength associated with more decomposition. Other factors, such as temperature and nutrient content also appear to be important and may provide important context for better understanding the role of algal priming in streams.

Steven Rier (Co-Presenter/Co-Author), Commonwealth University of Pennsylvania, srier@commonwealthu.edu;


Jennifer Soohy (Co-Presenter/Co-Author), Bloomsburg University, jat18435@huskies.bloomu.edu;


Emily Ashberry (Primary Presenter/Author), Bloomsburg University, ela77590@huskies.bloomu.edu;


Presentation:
This presentation has not yet been uploaded.

5/23/2019  |   09:45 - 10:00   |  254 B

FRESHWATER INVERTEBRATE ASSIMILATION OF MICROBIAL NUTRIENTS FROM DETRITUS UNDER LIGHT AND PHOSPHORUS MANIPULATION Recent studies have observed that periphytic algae can stimulate or prime heterotrophic microbial decomposers associated with decaying leaf litter, thus potentially modifying the flow of energy and nutrients to detritus feeding consumers in aquatic ecosystems. This study employed C and phosphorus (P) isotopic radiolabels to analyze how detrital microbial constituents (i.e. heterotrophs and autotrophs) contribute C and P to detritivore nutrition under raised light and nutrient regimes. We conducted a feeding study using Liriodendron tulipifera leaf litter conditioned under contrasting light and nutrient levels and fed to detritivorous caddisflies (Pycnopsyche sp.). We quantified detrital microbial biomass and production rates and caddisfly radiolabel assimilation and incorporation efficiencies. Increased light and nutrients stimulated detrital autotrophic and heterotrophic microbial activity. While leaf litter diets weakly affected Pycnopsyche acquisition of microbial P, acquisition of microbial C differed across microbial groups and diets. Overall, Pycnopsyche incorporated 94-97% microbial C from fungi and 1-3% from bacteria and algae. Our results show that light and nutrients can determine the quality of microbial nutrients available to detritivores, which may have important implications for our understanding of organic matter processing and energy flow in aquatic habitats.

Taylor Price (Primary Presenter/Author), The University of Southern Mississippi, taylor.l.price@usm.edu;


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


Steve Francoeur (Co-Presenter/Co-Author), Biology Department, Eastern Michigan University, steve.francoeur@emich.edu;


Kevin A. Kuehn (Co-Presenter/Co-Author), University of Southern Mississippi, kevin.kuehn@usm.edu;


Presentation:
This presentation has not yet been uploaded.

5/23/2019  |   10:00 - 10:15   |  254 B

THE EFFECTS OF NUTRIENT AND LABILE CARBON ADDITIONS ON THE PRIMING OF LEAF LITTER DECOMPOSITION BY POND SEDIMENTS Pond construction is a common anthropogenic modification to watersheds that is likely to alter organic matter processing. Our previous research has found that small ponds in central Virginia accumulate a large standing stock of terrestrial leaf litter (mean = 162 g AFDM m^-2) that decomposes slowly (mean k = -0.0030 d^-1). We have also found that leaf litter decomposition (measured as a change in toughness) is 42% faster when the litter is in contact with the pond sediments, indicating that the pond environment alters organic matter processing. In this experiment, we used microcosms to test the hypothesis that the accelerated leaf decomposition in the sediments was due to increased availability of inorganic N and P, and/or labile carbon in the sediment environment. Our results show that glucose additions did not alter decomposition rate (measured as the change in leaf toughness) but leaf decomposition rate was altered by N and P additions after 2 and 14 weeks of incubation. These results suggest that nutrient limitation more than labile carbon limitation affects the decomposition of terrestrial organic matter in the sediments of small ponds.

Alyssa Oppedisano (Primary Presenter/Author), Longwood University, alyssa.oppedisano@live.longwood.edu;


Gabrielle Huerta (Co-Presenter/Co-Author), Longwood University, gabrielle.huerta@live.longwood.edu;


Kenneth Fortino (Co-Presenter/Co-Author), Longwood University, fortinok@longwood.edu;


Matthew Waters (Co-Presenter/Co-Author), Auburn University, mwaters@auburn.edu;


Presentation:
This presentation has not yet been uploaded.

5/23/2019  |   10:15 - 10:30   |  254 B

EFFECTS OF CLIMATE VARIABILITY IN A LONG-TERM CONTEXT ON LEAF LITTER PROCESSING IN THE OGEECHEE RIVER Leaf litter decomposition (LLD) in stream ecosystems is an important component of the energy and nutrient cycle, representing an important process in the stream and a food source for aquatic organisms. This has made LLD a useful tool for assessing long term responses to disturbance. The Intergovernmental Panel for Climate Change (IPCC) predicts a rise in temperatures and changes to precipitation patterns for the 21st century. Specifically, for the southeast region, a higher frequency of drought and floods is predicted. My objective is to use long-term data (6 years of LLD data from the same site) to evaluate and predict the potential effects of climate variability on the leaf decomposition process and the invertebrate community associated with it. Preliminary results from 2012, a year following an extensive drought (>1 yr), versus subsequent years, reveal a higher rate of decomposition, insect abundance and diversity, and a shift to a majority scraper functional feeding group in comparison to a majority collector-gatherers from consequent years. This suggests changes in the availability and contribution of basal resources that may result in a shift in trophic structure.

Jose Sanchez-Ruiz (Primary Presenter/Author), Montana State University, jas091988@gmail.com;


Checo Colon-Gaud (Co-Presenter/Co-Author), Georgia Southern University, jccolongaud@georgiasouthern.edu;


Presentation:
This presentation has not yet been uploaded.