Variation among congeneric dinoflagellates from the northeastern United States and Canada

Biodiversity of Harmful Marine Algae

“…In the first inter-and intraspecific study of members of the A. tamarense and catenella species complex, isozyme analyses showed a high degree of enzymatic heterogeneity among isolates from the west coasts of the USA and Canada but indicated that isolates from the same locality were most closely related (Cembella and Taylor, 1986). In contrast, a relative lack of enzymatic heterogeneity was revealed by a similar analysis of Alexandrium populations from the east coast of the USA (Hayhome et al, 1989). Isozyme data suggested a common origin for the East Coast populations and supported the dispersal hypothesis along the East Coast of the USA from Canada down to Massachusetts, as related to hydrographic events dissipating a massive red tide that occurred in 1972.…”

Analysis of toxic and non-toxic Alexandrium (Dinophyceae) species using ribosomal RNA gene sequences

“…Some, but not all, representatives of this diverse group produce toxins responsible for paralytic shellfish poisoning, a neurotoxic disorder that has caused human illness for centuries and claimed hundreds of lives ( Quayle 1969, Prakash et al 1971. Like other harmful phytoplankton, toxigenic Alexandrium appear to be dispersing to regions of the world previously free of their presence (Anderson 1989. In some cases, populations of the same or similar species occur in different regions of the world, yet little is known of their genetic affinities.…”

“…The negative impacts of their "blooms" (sometimes called "red tides") are extraordinarily diverse, ranging from public health threats due to toxic fish or shellfish, to destruction of marine life and significant economic loss. In recent times, the list of known, harmful phytoplankton species has grown, new phytoplankton toxins have been discovered, and the frequency of harmful blooms and their geographic range appears to be expanding (Anderson 1989, Smayda 1990). Part of the difficulty in understanding the relationships between toxic and non-toxic phytoplankton species, their mechanisms of toxigenesis, and their bloom dynamics, population structure and apparent dispersal lies in the lack of methods that allow for unambiguous identification of the species in question.…”

“…These organisms pose an important problem in population biology and taxonomy, as well as a serious economic and public health concern (Anderson 1989). An alarming trend in recent years has been the apparent natural and human-assisted dispersal of toxic Alexandrium to regions of the world previously free of their presence (Anderson 1989. However, techniques to unambiguously distinguish between populations of these organisms are presently insuffcient to test specific dispersal theories.…”

“…Isozyme electrophoresis, toxin composition analyses and cell reactivity towards monoclonal antibodies (Cembella et al 1987, Hayhome et al 1989 have all been applied to assess the different morphospecies' relatedness.…”