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EVALUATION OF THE EFFECTS ON BENTHIC ORGANISMS FROM CLAY FLOCCULATION OF RED TIDE ORGANISMS
Citation:
Lewis, M A., R M. Greene, A. Li, AND D. M. Anderson. EVALUATION OF THE EFFECTS ON BENTHIC ORGANISMS FROM CLAY FLOCCULATION OF RED TIDE ORGANISMS. Presented at Symposium on Harmful Marine Algae in the U.S, Woods Hole, MA, 5-9 December 2000.
Description:
Evaluating the feasibility of controlling red tide using clay flocculation is part of an ECOHAB-funded project. One aspect for the feasibility and future application of clays is the determination of potential negative environmental impacts. The removal of toxin-containing dinoflagellates from the water column may result in acute or chronic toxicity to benthic organisms. Using EPA-approved standard toxicity test methods, we designed a study to determine the acute and chronic toxicities of settled G. breve cells, clay and coagulant to four species of marine life. The laboratory-conducted solid phase and pore water bioassays were of 4 to 28 days duration. The test species included the epibenthic and infaunal sheepshead minnow, grass shrimp, Leptocheirus plumulosus (amphipod), and Ampelisca abdita (amphipod). These species were exposed to the clay, coagulant and G. breve alone and in binary and ternary combinations at three treatment levels. Effects on organisms survival and reproduction were determined and reported as LC50 values, no effect concentrations, and the lowest effect concentration. In addition to the laboratory bioassays, we will determine benthic quality below a natural red tide event by analyzing sediment toxicity, chemical quality and benthic community composition. The results of the acute and chronic toxicity evaluations will be discussed in this presentation as well as their relevance to the in-situ remediation of red tide events.