Spatial and Seasonal Variation of Macroinvertebrate Biotic Indices of the Lower Ogeechee River Basin

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The Ogeechee is a blackwater river whose catchment is situated almost entirely in the Coastal Plain ecoregion of southeastern Georgia. Over the river’s course, it’s catchment experiences changes in land use, from agricultural to urban, as well as ecological changes from its Piedmont headwaters through its floodplain to the estuary at its mouth. Additionally, ecological communities within the river are subject to large seasonal physicochemical and hydrological shifts, including winter and spring flooding, that drive the life histories of the organisms in the river channel. Using macroinvertebrate community data collected from an ongoing study, we assessed seasonal and spatial differences in the community composition of the river using biotic indices. Benthic macroinvertebrates were sampled on a quarterly basis from summer 2014 until spring 2015 at 6 main channel locations along a longitudinal gradient on the Lower Ogeechee River Basin. We used community composition data to generate biotic indices for each sampling event at each site. Spatially there were few consistent trends for overall richness and tolerance metrics, with the two most downstream sites being slightly less taxonomically diverse and harboring fewer sensitive taxa, thus leading to lower scores in the GA Multimetric Index. Furthermore, little to no seasonal change was observed for many of the metrics with the exception of the Simpson Index and the Shannon Wiener function which yielded lower diversity scores in the winter and spring. Continuous monitoring data from multiple, consecutive years, combined with additional analyses of community structure and composition, should improve our understanding of the Ogeechee River’s overall health, condition and potential for natural fluctuations. This information is ultimately needed to aid in the future management of the system.


Georgia Chapter of the American Fisheries Society Annual Meeting (GA-AFS)


Statesboro, GA