Mario R. Sengco and Donald M. Anderson, Biology Department, Woods Hole Oceanographic Institution

Abstract

Clay minerals have been used successfully to treat harmful algal blooms (HABs) in Japan and South Korea. This control strategy is based on the mutual aggregation of clays and cells leading to the formation of larger, more-rapidly sinking particles that eventually settle to the ocean floor. The outcome is the physical removal of the causative species and the reduction of their deleterious impacts, with minimal effects of clay treatment on maricultured fish and the benthic environment.

The goal of this presentation is to provide managers with information on clay dispersal which they can evaluate and use determine whether clay is a suitable means of mitigating HABs in their jurisdiction. This talk will present our current understanding regarding the effectiveness of clay dispersal with respect to the following topics: (1) clay properties such as mineralogy and particle size, (2) properties of the target species, (3) clay and cell concentration, (4) the influence of treatment scale and hydrodynamics, and (5) the use of chemical flocculants to enhance cell removal efficiency. In addtion, this talk will include a discussion of the possible impacts of clay treatment on the chemical and biological properties of the water column and the benthic environment. It will include a short review of pertinent literature and recent laboratory studies.