#26 - A Comparison of Benthic Invertebrates in the Etowah River 1958 & 2018

Abstract

The Etowah River originates in Lumpkin County, northwest of Dahlonega. It flows south then west across North Georgia joining the Oostanala to form the Coosa River. It is famous for its biodiversity and is home to many threatened and endangered aquatic species.

Landscape use in North Georgia has changed in the past 100 years, shifting from agriculture to secondary regrowth of forests to increasingly large pockets of urbanization. This project examines benthic invertebrate composition change over sixty years in a small section of the Etowah.

Monthly benthic samples were taken at three locations in the section of the Etowah that borders Dawson Forest from October 1958 to September 1959. Organisms were identified to the lowest possible taxa level. These were the ‘before’ samples for a project to assess radiation impact on the river from an unshielded reactor. The project and the reactor were shut down and the data was stored.

We replicated equipment and collection sites from September 2017 to September 2018. Organisms were identified to lowest possible taxa and organic matter was identified and weighed. September and October and November 2017 samples have been analyzed.

There does not seem to be a huge difference in composition which may be due to the fact that the watershed was recovering from heavy agricultural use in the 1950s and has been relatively protected since then. This is changing rapidly with urbanization. Anecdotal evidence suggests large quantities of sand have reduced heterogeneity and depth in some areas.

The discussion of species loss and baseline shifting is in the news now. Our present day understanding of what is here is very different from what was here. We suggest that the boxes in closets containing field notebooks and old vials be checked to find interesting and important archived data.