STREAM BENTHIC MACROINVERTEBRATE COMMUNITIES RESPOND TO HEMLOCK DECLINE
Eastern hemlock trees often dominate the vegetation in riparian zones of headwater ravine streams in central Appalachia, and the invasive pest Hemlock Woolly Adelgid (HWA) has decimated hemlock stands in this region. Although research concerning HWA impacts on soil, hydrology, and forest structure is emerging, associated changes in stream structure and function is less known. We quantified HWA invasion effects on the structure and potential functions of benthic macroinvertebrate communities in 21 headwater streams across Ohio, West Virginia, and Virginia, representing unimpacted, intermediate, and severe invasion intensity, respectively. We observed differences in benthic invertebrate composition; severely invaded sites had the highest diversity, while intermediate sites had the lowest diversity. Functional composition exhibited shifts as well; for example, the relative abundance of herbivorous invertebrates increased from 4% (±3%) at unimpacted sites to 23% (±14%) at severely impacted sites, consistent with an observed decrease in non-labile hemlock needles. Our results suggest that resource alterations associated with HWA-invasion and subsequent hemlock decline are associated with changes in stream invertebrate diversity and trophic relationships. We demonstrate how a pervasive terrestrial invader can influence in-stream biotic communities and their functions.
Kristen M. Diesburg (Primary Presenter/Author), The Ohio State University, firstname.lastname@example.org;
S. Mažeika P. Sullivan (Co-Presenter/Co-Author), The Ohio State University, email@example.com;
David W. P. Manning (Co-Presenter/Co-Author), The Ohio State University, firstname.lastname@example.org;