Quality Of The Nuisance Diatom Didymosphenia Geminata For Macroinvertebrate Nutrition In A Southeastern U.S. Hypolimnetic Tailwater River

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Stephanie Sellers (Creator)
Appalachian State University (ASU )
Web Site: https://library.appstate.edu/
Shea Tuberty

Abstract: Didymosphenia geminata is a mat-like, colony forming diatom native to areas of western North America and found in high elevation oligotrophic rivers across the Northern and Southern Hemispheres. The alga has drawn concern in recent decades due to its negative impacts on the community makeup of benthic macroinvertebrates in streams where it is considered a nuisance or invasive species. Diatoms can serve as a major food source for aquatic macroinvertebrates, however colonies of D. geminata are often much larger and more abundant than populations of other diatoms. The C:N ratios of aquatic plant tissue can serve as an indicator of both the availability of nutrients to the plant and the capacity for transfer of available nutrients to primary consumers. In September 2016 we conducted a study in the South Fork Holston River tailwater in eastern TN, USA to determine the nutritional quality of D. geminata for benthic macroinvertebrates as it compares to native tailwater flora. Samples of nine aquatic macrophyte and submergent plant taxa including D. geminata were collected from three tailwater sites downstream of the South Holston Reservoir to better understand the impacts of cool, hypolimnetic releases on plant tissue quality. C:N ratios of all samples were measured using a Flash Elemental Analyzer (Thermo Fisher Scientific). Tissue quality of D. geminata did not differ significantly from any other study taxa. C:N ratios of two angiosperm and one bryophyte species decreased significantly with increasing distance from the dam, and the C:N ratios of two of these species were positively correlated with mean annual mean temperatures. The C:N ratio of a filamentous algae increased significantly moving away from the dam and was negatively correlated with annual mean temperature. Our results indicate that D. geminata may serve as a food source of comparable quality to native floral species for tolerant benthic macroinvertebrate taxa (e.g. Chironomidae), and our data suggest that the impacts of hypolimnetic releases on tissue quality of aquatic plant taxa are mitigated within a relatively short distance from the dam.

Additional Information

Honors Project
Sellers, S. (2017). "Quality Of The Nuisance Diatom Didymosphenia Geminata For Macroinvertebrate Nutrition In A Southeastern U.S. Hypolimnetic Tailwater River." Unpublished Honors Thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2017
South Fork Holston River Tailwater, Didymosphenia geminata, Freshwater benthic macroinvertebrate diversity, C:N ratio, Elemental analysis

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