Penna, A.; Garcés, E.; Vila, M.; Giacobbe, M. G.; Fraga, S.; Lugliè, A.; Bravo, I.; Bertozzini, E.; Vernesi, C.
2005
<i>Alexandrium catenella</i> (Dinophyceae), a toxic ribotype expanding in the NW Mediterranean Sea
Marine Biology
148(1): 13-23
Publication
The presence of the paralytic shellfish poisoning
(PSP) dinoflagellate Alexandrium catenella in the north
western (NW) Mediterranean Sea has been known since
1983. From this date on, the species has spread along the
Spanish and Italian coastlines. Information concerning
A. catenella isolates in the NW Mediterranean Sea was
gained through phylogenetic studies. Twenty established
toxic cultures of A. catenella taken from various NW
Mediterranean Sea locations were analysed by nucleotide sequencing of the 5.8S rDNA and internal transcribed spacer regions. These rDNA ribosomal markers resulted useful in delineating the phylogenetic position of this species in the genus Alexandrium as well as in determining relationships between A. catenella isolates from different geographic areas. The phylogenetic position of the Mediterranean A. catenella ribotype, when compared to the ‘‘Alexandrium tamarense/catenella/fundyense species complex’’, fits this species complex well. All the Mediterranean A. catenella isolates were constituted by only one genetic ribotype. By comparing the isolate sequences with those of other geographic areas, it revealed that the
Mediterranean A. catenella ribotype was closely related to the A. catenella from Japan, Western Pacific Ocean. It was also evident that in temperate Japanese waters, a genetic variability was detected within A. catenella iso-
lates; in fact, all strains resulted divergent showing as many as 15 mutational steps. The possibility that A. catenella has been recently introduced into the Mediterranean basin from temperate Asian areas is discussed.