Biomonitoring of Ogeechee River Invertebrate Assemblages: Patterns of Community Structure

Document Type


Publication Date



Benthic invertebrates are important in river food webs, where they link between algal and detrital energy sources to insectivorous fish. In the Ogeechee, a free flowing 6th order river on Georgia’s Atlantic Coastal Plain, seasonal and spatial variation plays a key role in the structuring of invertebrate communities, with implications for the fish that feed on them. Routine biomonitoring of streams and rivers to assess water quality requires collection of macroinvertebrate samples, which can be used to assess community structure. To identify patterns in structure and to assess water quality on the Ogeechee, quarterly invertebrate samples were taken from six sites along the river for three years, identified to lowest practical taxonomic level, and analyzed based on water quality indices, diversity indices and community structure. Indices of diversity and water quality were constant across sites, but diversity dropped in the winter and spring, corresponding with outbreaks of certain dominant taxa such as isopods. Community structure varied significantly by site and season. During the summer and fall, mayflies such as Caenis and Tricorythodes were common, whereas the mayfly Baetisca had outbreaks in the winter. Midges of the family Chironomidae were numerous year-round but only dominant in the summer and fall. Winter and spring samples were dominated by the isopods Lirceus and Asellus. Understanding what food resources are available at different times of year help indicate when fish are most productive and most vulnerable.


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


Helen, GA