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TOXICITY OF CLAY FLOCCULATION OF RED TIDE ORGANISMS ON BENTHIC ORGANISMS ERF 2001
Citation:
Lewis, M A., R M. Greene, A. Li, AND D. M. Anderson. TOXICITY OF CLAY FLOCCULATION OF RED TIDE ORGANISMS ON BENTHIC ORGANISMS ERF 2001. Presented at ERF 2001: An Estuarine Odyssey, St. Pete Beach, FL, 4-8 Nov., 2001.
Description:
Toxicity of Clay Flocculation of Red Tide Organisms on Benthic Organisms (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ERL,GB R854).
We have evaluated the feasibility of controlling red tide using clay flocculation as part of an ECOHAB-funded project. To determine the feasibility and future applications of clays, potential negative environmental impacts need to be evaluated. The removal of toxin-containing dinoflagellates from the water column and the subsequent settling of flocculents to the bottom 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 several species of marine life (see below). The laboratory-conducted solid phase and pore water bioassays were of 4 to 28 days duration. The test species included Cyprinodon variegatus (sheepshead minnow), Palaemonetes pugio (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 organism survival and reproduction were determined and reported at LC50 values, no effect concentrations, and the lowest effect concentration. In addition to the laboratory bioassays, we plan to 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.