Assessing long-term ecological change in the Ogeechee river using aquatic invertebrate communities

Anthropogenic impacts are a threat to rivers worldwide, and aquatic insects are important to assessing environmental change. In the 1980s, researchers preformed collections of macroinvertebrates on submerged woody debris in the Ogeechee River (Georgia, USA) for two years. We collected invertebrates from 2015 to 2017 with the same methodology to compare communities. We documented greater taxonomic richness and change in community structure compared to the 1980s. We also documented a decline in total insect biomass; however, overall abundance was similar, indicating a decline in size of individuals. Specifically, larger consumer taxa mostly decreased, while smaller consumer taxa and most predator taxa increased in number. Additionally, functional trait richness of the community increased over three decades, but functional dispersion has not changed. Focusing on caddisflies, we examined ecological basis of change and larval morphology of an understudied genus. These results provide a unique perspective on long-term environmental changes in river systems.