A comprehensive review was undertaken of the distribution of the toxic dinoflagellate Alexandrium minutum Halim. The primary threat to humans caused by A. minutum is because of the production of paralytic shellfish toxins (PSTs) which can accumulate in seafood vectors, which if consumed lead to the human condition known as paralytic shellfish poisoning. Within this work it became apparent that the known global spread of this important species has increased, either due to range expansion, as a consequence of improved or novel investigation, or as a combination of these factors.
Those populations of A. minutum capable of producing PSTs display a range of different toxin profiles with differing saxitoxin derivatives or differing proportions of common toxins being present. As yet no genetic basis for these differences in toxin productivity has been isolated although there are currently 4 recognised clades within the A. minutum species the two principle clades being the Pacific and the Global. A novel analysis of A. minutum toxin profiles was undertaken by applying K means clustering to PST profiles extracted from the literature. This analysis generated 5 distinctive clusters, each relating to a statistically separable toxin profile. Interestingly examples of each of the two major clades had representatives from different toxin profile clusters. This suggests further, currently undetermined genetic separation or relatedness between clades, as the differences in the ITS region of the ribosome upon which the clades are based, does not seem to be coupled to the specifics of the toxin profile. It also raises the possibility that there is an environmental driver for the differing toxin profiles, although profiles clustered geographically in some cases in others they were either cosmopolitan or spatially isolated. This new approach offers an additional tool with which to examine the relationships between populations and target further genetic research
