Top-down interactions in streams draining human-modified landscapes at the Coweeta Hydrologic Laboratory from 1997 to 1998: Gradient algae data

Spatial and temporal variability of consumer-controlled forces have been the subject of much debate in ecology. To date, most studies considering variability of these top-down interactions have focused on systems minimally impacted by human activities. However, human modification of the landscape is prevalent, and it can significantly affect the strength and outcome of species interactions. The objective of this study was to examine how top-down interactions vary among streams with differing amounts of human disturbance in their watersheds. To address this issue, we experimentally excluded macroconsumers (fishes and crayfishes) from benthic areas of five southern Appalachian streams. These sites represented a range of human watershed development, from 100% to < 50% forested; macroconsumer assemblages at low development sites were dominated by benthic insectivores (Cottus bairdi) and crayfishes, whereas algivores (Campostoma anomalum) and general insectivores (e.g., Notropis leuciodus) were common at more developed sites. Using ceramic tiles as sampling substrates, we compared sediment, algal assemblages (chlorophyll a, AFDM, abundance, biovolume, and composition), and insect assemblages (abundance, biomass, and composition) in macroconsumer exclusion and control areas.