Characterization of Indigenous and Introduced Toxic Phytoplankton in Antarctica

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Abstract OPP-9615831 There are thousands of species of marine phytoplankton, but only a few produce potent toxins. These species are found in the massive `red tides" or blooms of cells that discolor the water. More commonly, the organisms are present at low concentrations and are noticed only by the effects their toxins have on aquatic organisms and humans. The nature of the toxic phytoplankton problem has changed considerably in recent years as many areas that were previously unaffected are now subject to recurrent outbreaks. Therefore, it is alarming that marine algal toxins (saxitoxins) have been found in Antarctic molluscs. The implications of this discovery are profound given the low number of trophic levels between primary producers and top predators and the proven ability of the saxitoxins to alter the food web structure and dynamics. Saxitoxins can affect zooplankton, fish larvae, whales, porpoises, seabirds, and humans. A concern is that the saxitoxin-producing alga, presumably the dinoflagellates in the genus Alexandrium, has been introduced to Antarctic waters, possibly by vessel traffic between South America and the Antarctic Peninsula. This mechanism of species dispersal has been implicated in the sudden appearance of toxic algae in other areas of the world. Short and frequent transport pathways do exist between Antarctic and the high-toxicity waters of southern Chile and Argentina. It is also possible that the saxitoxins-producing organism is indigenous to Antarctica and was only recently noticed. In either case, the implications to the Antarctic food web are significant. The objectives of this proposal are to identify and characterize the possible source(s) of saxitoxins in Antarctica to determine whether the causative organisms are indigenous or introduced species, and if introduced, to identify the probable origin and transport pathway.