DO STREAM INVERTEBRATE FUNCTIONAL FEEDING GROUPS REFLECT MACROSCALE VARIATION IN TERRESTRIAL VEGETATION?
A central tenet of the River Continuum Concept is that functional traits of benthic invertebrates will covary with the longitudinal gradient of physical factors formed along the drainage network. For example, a shift from shredder- and collector-dominated invertebrate assemblages to assemblages composed primarily of collectors and grazers is predicted as one transitions from small headwater streams to larger mid-reaches. This change should occur because headwater streams with extensive tree canopies depend on allochthonous (leaf litter) resources while mid-reach streams are more likely to have open canopies and higher instream primary production (algae); shredders utilize leaf litter while grazers feed on algae. Using similar logic, it may also be possible to predict functional feeding group responses to terrestrial vegetation at macroscales. We collected benthic macroinvertebrate samples from six small North American streams, distributed across a broad latitudinal and longitudinal gradient. Satellite-derived indicators of terrestrial vegetation (e.g., the normalized difference vegetation index, or NDVI) are now being compared with functional feeding group data at each site to test the hypothesis that NDVI covaries with shredder biomass (positive relationship) and grazer biomass (negative relationship).
Adriana Diaz (Primary Presenter/Author), University of Texas Rio Grande Valley, firstname.lastname@example.org;
Daniel McGarvey (Co-Presenter/Co-Author), Virginia Commonwealth University, email@example.com;
Frank Dirrigl (Co-Presenter/Co-Author), University of Texas Rio Grande Valley, Frank.firstname.lastname@example.org;