GENETIC VARIABILITY IN TOXIN POTENCIES AMONG SEVENTEEN CLONES OF <em>GAMBIERDISCUS TOXICUS</em> (KINOPHYCEAE).

Seventeen clones of the ciguatera-causing dinoflagellate Gambierdiscus toxicus Adachi and Fukuyo were to the same environments over several months. Signifacant variance environments over detected between non-acclimated and acclimated cultures for cell potencies, yields and reproduction rates. The resultant variance in acclimated potencies, yields and reproduction rates. The resultant variance in acclimated potencies among clones was statistically significant (P < 0.0001), indicating that potency can be used for a clone of G. toxicus in the acclimated vs. non-acclimated phases can exceed genetic differences between clones. This stresses the need for a rigorous acclimation process. Caribbean isolates of G. toxius were inherently more toxic than isolates from the other areas. One Caribbean clone yielded 55 × 10[sup-4] mu (mouse units)· cells[sup-1] where clones from Bermuda, the Bahamas, and Florida ranged from only 1.8 × 10[sup-4] Mu cell[sup-1] to a maximum of 19.8 × 10[sup-4] mu· cell[sup-1]. Toxicity decreased with increasing latitude (r = 0.819, P < 0.01), indicating that environmental differences probably influenced the potencies, A comparison of acclimated reproduction rates at four light intensities also indicated that genetic differences among clones existed. The resulting reproduction rate/light slopes overlapped, indicating that the clones may be adapted to specific light regimes. [ABSTRACT FROM AUTHOR]