research

Resource Ratio Effects on Microbial Activity and Detritus Elemental Composition - Along with Michelle Evans-White (University of Arkansas) and Sally Entrekin (University of Central Arkansas), we were recently funded by the National Science Foundation (DEB ) to evaluate the mechanistic links between nutrient enrichment and macroinvertebrate diversity in Ozark streams. The lability of leaf litter and the availability of potentially growth-limiting nutrients such as phosphorus can influence the activity of microbial decomposers. The Scott lab is investigating how variability in carbon lability and phosphorus availability (from the water column) affects microbial respiration and phosphorus uptake and release by fungi and bacteria decomposing leaf litter. Our objective is to quantify how the elemental composition of leaf litter varies due to natural (differences in leaf litter species) and human-induced (anthropogenic P enrichment) environmental change. The Evans-White and Entrekin labs are study how variability in the elemental composition of leaf litter affects the physiology, health, and ultimately community composition of shredding macroinvertebrates.

Ecological Stoichiometry of Prokaryotic Heterotrophs - Ecological stoichiometry is a conceptual framework that integrates important theories from population, community, and ecosystem ecology in order to assess patterns of element mass balance across multiple levels of biological organization. This conceptual framework is proving to be an enormously valuable tool for exploring ecological processes and patterns in many environments. In colloboration with Jim Cotner at the Univeristy of Minnesota, we have been exploring the biological stoichiometry of heterotrophic bacteria in order to better understand the role of these organisms as phosphorus sources or sinks in aquatic ecosystems.

Eutrophication and Fisheries Management - Water quality managers are usually seeking to decrease productivity in waters that have experienced human-derived nutrient enrichment. However, the recovery of eutrophic waters from reductions in nutrient loading ('oligotrophication') can result in decreased fisheries production. Therefore, the management of surface waters simultaneously for multiple uses that include consumption, recreation, and fisheries should consider this delicate balance. We are working with the Bella Vista Property Owners Association to develop novel ecosystem management techniques that will enhance sport fish production while maintaining high water quality.

Denitrification and Nutrient Storage in Reservoirs - The use of synthetic nitrogenous fertilizer by humans may be increasing nitrogen export from the Mississippi River and expanding the seasonal hypoxic zone in the Gulf of Mexico. However, only a fraction of land applied N fertilizer may actually be exported to coastal systems. Mass balance studies have shown that river impoundment reservoirs can retain significant quantities of their N loads and may be important N sinks in the landscape. However, few studies have directly assessed the mechanisms controlling reservoir N retention. We are studying the role of sediment denitrification in small (farm ponds) and large reservoirs in Arkansas to determine its importance for N retention on the landscape.