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SFS Annual Meeting

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MACROINVERTEBRATE RESPONSE DIVERSITY INCREASED IN ATMOSPHERICALLY ACIDIFIED STREAMS OVER A 26 YEAR PERIOD (1984-2009)

Acidification inhibits macroinvertebrate ion balance resulting in decreased taxa richness and density. Despite historical declines in macroinvertebrate diversity in acidified streams within Shenandoah National Park (SNP), observed air quality improvements could indicate biotic recovery. Yet, our understanding of macroinvertebrate response and ecosystem impacts to acidification is limited. We used macroinvertebrate traits to inform temporal and spatial functional changes within SNP streams. Functional traits were compared for 24 sites over three geologic classes with differing acid neutralizing capacity (ANC) (9 siliciclastic, 9 granitic, and 6 basaltic). We predicted that shredder and scraper density and richness within functional groups (response diversity) would increase across a gradient of pH recovery. We also predicted these increases would be greater in high ANC streams. We found no trends in overall densities. Response diversity increased over time for both shredders (1-12 taxa) and scrapers (1-11 taxa), with greatest increases at moderately acidified (granitic) streams. Taxa richness recovery was least pronounced in more acidified (silicicilastic) streams where dominant shredders (Amphinemura and Pteronarcys) and scrapers (Blepharicera and Drunella) remained absent. Further analysis will identify traits that predict changes in secondary production to inform how acidification impacts stream function.

Craig Snyder (Co-Presenter/Co-Author), csnyder@usgs.gov , cdsnyder02@gmail.com ;


Kelly Maloney (Co-Presenter/Co-Author), USGS, kmaloney@usgs.gov;


Sally Entrekin (Co-Presenter/Co-Author), Virginia Tech, sallye@vt.edu;


Kelly McIntyre (Primary Presenter/Author), Virginia Polytechnic Institute and State University, mcintyrek@vt.edu;