Comparison of Toxin Composition Between Populations of Alexandrium spp. from Geographically Distant Areas

Abstract

Axenic clonal isolates of the dinoflagellates Alexandrium tamarense and A. catenella derived from benthic cysts from Ofunato Bay (Iwate Prefecture, Japan), Tanabe Bay (Wakayama Prefecture, Japan) and motile cells from the Seto Inland Sea were subjected to toxin analysis by HPLC. Toxin contents and compositions of two or four sexually different vegetative cell germinated from each cyst were compared. In A. tamarense, the toxin compositions (mole %) of six isolates were relatively constant, but one isolate showed a clear distinction in a lack of N-suIfocarbamoyl (Cx) toxins. In A. catenella, the toxin composition was rather uniform within a geographical region. Moreover, toxin compositions of A. catenella isolates from Tanabe Bay and the Seto Inland Sea were clearly distinguished from those of A. catenella from Ofunato Bay. These results indicate the occurence of inter-and intra-specific indigenous populations from distant localities, and the toxin profiles separate one morphospecies into two regional populations. © 1993, The Japanese Society of Fisheries Science. All rights reserved.