Harmful Algal Blooms (HABs) are becoming an increasing problem to human health and environment (including
effects on natural and cultured resources, tourism and ecosystems) all over the world. There are about 70 species of
planktonic and non-planktonic microalgae considered harmful in world wide coasts. The most important toxinproducing
species are the dinoflagellates Alaxandrium monilatum, Gymnodinium catenatum and Pyrodinium
bahamense var. compressum, in the world, and consequently the poisonings documented in india are Paralytic
Shellfish Poisoning (PSP) and Neurotoxic Shellfish Poisoning (NSP). Toxic A. monilatum produces endotoxins with
hemolytic and neurotoxic properties, and has been linked to major fish and invertebrate kills. The responses of three
ecologically important shellfish species to A. monilatum (toxic strain AMO3) were experimentally assessed. In the
first set of experiments, grazing studies were conducted with adult and juvenile eastern oysters (Crassostrea
virginica Gmelin), northern quahogs (Mercenaria mercenaria Linnaeus), and green mussels (Perna viridis Linnaeus),
which inhabit areas where A. monilatum blooms occur. The type of phytoplankton and epiphytic microalgae, their
toxins and harmful effects as well as current methodology used to study these phenomena are presented in this
paper. As an experienced group of workers, we include descriptions of monitoring and mitigation programs, our
proposals for collaborative projects and perspectives on future research.
Abstract