Date of Award

8-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Wildlife and Fisheries Biology

Committee Member

Dr. John H. Rodgers Jr., Committee Chair

Committee Member

Dr. James W. Castle

Committee Member

Dr. George M. Huddleston III

Abstract

Sodium carbonate peroxyhydrate (SCP), a granular algaecide containing hydrogen peroxide (H2O2), is used to mitigate risks associated with noxious algae. Episodic exposures of SCP algaecides in aquatic systems prompt the need for a fundamental understanding of exposure-response relationships for aquatic organisms, both target and non-target, exposed to H2O2 as SCP. In the first experiment, influences of organic carbon on exposures of H2O2 as SCP and consequent responses of a frequent problematic alga (cyanobacterium Microcystis aeruginosa) were measured. Results indicate that the exposure of H2O2 as SCP necessary to control growth of a noxious alga is proportional to the density of the population. Using both density and the concentration of algal derived DOC to scale laboratory results to an in situ treatment could improve exposure predictions, which could decrease the chance of applying an ineffective concentration and maintain margins of safety for non-target organisms. In the second experiment, innate sensitivities of M. aeruginosa and non-target organisms including a eukaryotic alga (chlorophyte Pseudokirchneriella subcapitata), a microcrustacean (Ceriodaphnia dubia), a benthic amphipod (Hyalella azteca), and a fathead minnow (Pimephales promelas) were measured in relatively unconfounded, 96-h laboratory exposures of H2O2 as SCP. Results were used to interpret potential risks from SCP applications in aquatic environments. In terms of sensitivities, M. aeruginosa ≈ C. dubia > H. azteca > P. subcapitata > P. promelas to exposures of H2O2 as SCP. These results can be used to predict the distribution of responses likely to occur in situ, and indicate that SCP could mitigate risks associated with noxious cyanobacterial growths (e.g. M.aeruginosa) while providing a margin of safety for non-target species. In the final experiment, experiments were conducted in the laboratory to physically model a site-specific exposure-response relationship and predict H2O2 exposures and target algal responses prior to the application of an SCP algaecide in a southeastern U.S. reservoir. Portions of the Six and Twenty Creek cove of Hartwell Lake, a man made reservoir bordering South Carolina and Georgia, were treated with Phycomycin® SCP (27% H2O2) to control an algal assemblage producing taste and odor. By utilizing algae and water from the study site in both laboratory and field experiments, differences in potential exposure modifying factors (i.e. water characteristics and specific algal sensitivity) were minimized, resulting in exposures and responses measured after the in situ application of SCP that were comparable to laboratory predictions. Exposures of H2O2 as SCP were labile and dynamic, thus an indirect comparison of laboratory and field experiments (i.e. responses observed in situ were used to infer the causative exposure based on results from the laboratory model) was necessary to corroborate the direct comparison of experiments (i.e. exposures eliciting equivalent responses were compared). Data from the experiments in this thesis increase our fundamental understanding of exposure-response relationships from SCP algaecides, and provide information supporting the effective and ecologically sound use of SCP algaecide in water resource management.

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