ECOHAB: Control of Harmful Algal Blooms using ClayEPA Grant Number: R827090
Title: ECOHAB: Control of Harmful Algal Blooms using Clay
Investigators: Anderson, Donald M. , Bricelj, V. Monica , Chapman, Peter , Greene, Richard M. , Lewis, Michael , Pierce, Richard
Current Investigators: Anderson, Donald M. , Bricelj, V. Monica , Greene, Richard M. , Lewis, Michael , Pierce, Richard
Institution: Woods Hole Oceanographic Institution , Mote Marine Laboratory
Current Institution: Woods Hole Oceanographic Institution
EPA Project Officer: Hiscock, Michael
Project Period: November 23, 1998 through November 22, 2001 (Extended to November 22, 2002)
Project Amount: $332,938
RFA: Ecology and Oceanography of Harmful Algal Blooms (1998) RFA Text | Recipients Lists
Research Category: Water Quality , Harmful Algal Blooms , Water , Ecosystems
Throughout the United States and the world, red tides and harmful algal blooms (HABs) pose a serious and recurrent threat to marine ecosystems, fisheries, human health, and coastal aesthetics. These phenomena are caused by the growth and accumulation of microscopic algae, some of which produce potent toxins. The significant public health, economic, and ecosystem impacts of HABs suggest that these phenomena would be legitimate targets for direct control or mitigation efforts, but no significant research on HAB control strategies has been undertaken in the United States for 40 years, even through human efforts to control insects, diseases, and weed species are common agricultural practices on land. This project will investigate the feasibility of a promising control strategy - the removal of cells from the water column using clay flocculation. The general objectives are to use laboratory cultures, aquaria, and mesocosms to: 1) determine the removal efficiencies of selected clays on three HAB species found in U.S. waters (the Florida red tide dinoflagellate Gymnodinium breve, the New York brown tide chrysophyte Aureococcus anophagefferens, and to a lesser extent, fish-killing Pfiesteria-like dinoflagellates; 2) determine the variability in cell removal efficiencies due to such factors as species differences, growth stage, and cell density; 3) determine whether cell removal efficiencies can be improved by addition of alum or polymeric coagulants; 4) investigate changes in water chemistry following clay treatment, including the release or removal of nutrients such as phosphorous and nitrogen, release of radioactivity, trace metals and other toxicants; 5) investigate brevetoxin release and uptake by clays during the flocculation process; 6) investigate the use of clays to mitigate the impacts of aerosolized brevetoxins; 7) conduct aquarium and mesocosm studies to examine flocculation efficiencies on natural plankton assemblages and to assess the impacts of sedimented biomass and toxins on benthic organisms; 8) evaluate the engineering requirements, economic costs and environmental clearances needed for a pilot program for field application of this mitigation strategy.
The approach, which is based on research and practical field trials in Japan, China, Korea, and the PI's laboratory, relies on the ability of certain clays to scavenge particles, including algal cells, from seawater, carrying them to bottom sediments where they are buried and decomposed. The project will begin with small-scale laboratory experiments in which algal cultures in test tubes are treated with clays and cell removal, cell viability, toxin release, and other parameters are measured. Laboratory experiments will also examine nutrient uptake and release by clays applied to seawater containing no algae. These and other laboratory experiments will be conducted on each of the targeted HAB species. Work will then shift to aquaria or mesocosm tanks where the clay treatments will be applied to natural communities of planktonic and benthic organisms.
No studies have yet been conducted on the loadings needed to remove U.S. HAB organisms, on the suitability of readily available U.S. clays, or of the possible environmental impacts of flocculation and sedimentation of bloom organisms, especially those containing toxins. The eventual conclusion from the investigations proposed here will be of great value in evaluating the feasibility and potential environmental impacts of this promising bloom mitigation strategy. Knowledge will have been gained that can steer us towards related strategies that may someday help us minimize the impacts of some HABs.