Morphological and biochemical variability of the toxic dinoflagellate Prorocentrum lima isolated from three locations at Heron Island, Australia

Seventeen clones of the toxic, epiphytic-benthic dinoflagellate Prorocentrum lima (Ehrenberg) Dodge isolated from three separate sites on the reef flats of Heron Island, Australia, were acclimated under the same set of environmental conditions. Morphological features examined for each clone included cell surface configuration, size, and dry weighs. Physiological and biochemical features determined for each clone included reproduction rates, pigments (chlorophyll a, chlorophyll c(2), peridinin, and other xanthophylls), toxins (okadaic acid and methyl-okadaic acid), and macromolecular compounds (total protein, lipid, and carbohydrate). Variation in morphological features and reproduction rates of clones within and between sites was minimal and not significant. Also, variation in biochemical features within an individual site was low, but pronounced differences existed among sites, the most notable of which was toxin content (okadaic acid and methyl-okadaic acid). The greatest difference in biochemical features was between clones isolated from the southern site and clones isolated from the northern and southeastern sites. Results of a cluster analysis of clonal characters support the view that these two groups represent distinct genotypes. We suggest that these groups originated from separate seed sources and that the genetic integrity of each is maintained through asexual reproduction.