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SFS Annual Meeting

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VARIABILITY IN INVERTEBRATE ECOLOGICAL TROPHIC NETWORKS ALONG A GRADIENT OF NUTRIENT ENRICHMENT

Food webs represent one of the principal categories of ecological networks, which describe biotic interactions and integrate energy pathways within ecosystems. These ecological networks can be vulnerable to changes in land use and cover associated with anthropogenic activity, such as nutrient enrichment. In streams, nutrient enrichment can alter the amount and type of basal resources available for consumers, which in turn alters food-web dynamics. Here, we investigate the complexity and architecture of invertebrate ecological trophic networks in streams as a function of in-stream nitrogen and phosphorus concentrations. Preliminary results indicate that functional feeding group composition of macroinvertebrate communities varies by total phosphorus and orthophosphate concentrations, shifting towards higher relative abundances of scraper-grazers at higher concentrations. Connectance – which reflects the proportion of links among species that are realized – appears to be negatively correlated with nitrate concentrations. These results provide initial evidence that nutrient enrichment may alter invertebrate trophic networks with implications for energy flow and upper food-web compartments. Subsequent analysis will explore nutrient relationships with trophic-network characteristics representing additional species, link, and chain properties.

Travonya Kenly (Primary Presenter/Author), The Ohio State University , kenly.1@osu.edu;


S. Mažeika P. Sullivan (Co-Presenter/Co-Author), The Ohio State University, sullivan.191@osu.edu;