Distribution of hyporheic cyclopoids (Crustacea: Copepoda) in the eastern United States

Abstract

We sampled the hyporheic cyclopoid copepods of 14 unpolluted sites in the eastern United States to test whether community composition differed between glaciated and unglaciated sites. We found 31 species of cyclopoids in all, over half of which were new to science or only recently described. All of these newly discovered species were interstitial specialists (stygobionts) living in the unglaciated Southeast, suggesting that many new species of hyporheic cyclopoids remain to be found in this region. Glaciated sites contained fewer species of interstitial specialists (but not fewer species of generalists) and fewer narrowly endemic species than unglaciated sites. Further, ordination results suggest that there is a break in species composition near the glacial border. In contrast, local ecological conditions had much weaker effects on species composition. We also found strong differences between interstitial specialists and generalists in local distributions within our study sites and in range size-abundance relationships. Our results thus show that glaciation has strong residual effects on the composition of present-day communities of hyporheic cyclopoids.