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SFS Annual Meeting

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IS INDIVIDUAL BODY SIZE A RELIABLE PREDICTOR OF TROPHIC POSITION IN EASTERN U.S. STREAMS?

Because predators must be large enough to capture, handle, and ingest their (usually smaller) prey, trophic position (TP) is generally predicted to increase with body size. However, empirical studies of the relationship between size and TP in aquatic ecosystems have yielded mixed results, with strong positive relationships reported in some systems and weak or non-existent relationships reported in others. We collected fish and invertebrate stable isotope samples from four eastern U.S. streams, distributed along a latitudinal gradient from ~39°N (Front Royal, VA) to ~33°N (Moundville, AL), to test for a positive body mass vs. TP relationship. Importantly, we use body mass and TP estimates from individual specimens, rather than species-level averages, in our analyses; this is done to account for ontogenetic shifts in feeding behavior, which can bias species-level estimates that only incorporate juvenile or adult size and TP data. Finally, we use linear regression to test for differences in the body mass vs. TP relationship among sampling sites.

Daijona Revell (Primary Presenter/Author), Virginia Commonwealth University, revelldt@mymail.vcu.edu;


Serena Moncion (Co-Presenter/Co-Author), University of Virginia, sam7dz@virginia.edu;


Raquel Wetzell (Co-Presenter/Co-Author), Virginia Commonwealth University, wetzellrm@mymail.vcu.edu;


Felisha Walls (Co-Presenter/Co-Author), Virginia Commonwealth University, wallsfn@vcu.edu;


Daniel McGarvey (Co-Presenter/Co-Author), Virginia Commonwealth University, djmcgarvey@vcu.edu;