Health effect attributions implications

The events of 1997 had a major impact on research funding for HABS and spurred the adoption of molecular techniques for detection and monitoring of HAB species. Pfiesteria spp. can now be detected and identified in natural water and sediment samples and also at hsh kill events. The current data from these studies indicates a low abundance in nature for these species and no indication of involvement in any hsh kill event since 1998. While a toxic free radical generating activity has been described, the uniqueness to Pfiesteria spp. for this activity and the in situ detection of the activity have not been established. In contrast, K. veneficum has a worldwide distribution, and has been implicated in numerous hsh kill events around the world since 1950, a toxin has been isolated, its structure determined, and rigorously quantihed at specihc hsh kill events. Therefore, we present a scenario for the co-occurrence of K. veneficum and Pfiesteria spp., which explains the hsh kill events of 1997, and subsequent similar events attributed to Pfiesteria spp. The cause(s) for the proposed human health detrimental effects of these events are still unclear. 

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