In fact, it appears
that only one published study has performed light experiments
with cell-free preparations from P. parvum (Parnas
et al., 1962), using artificial light and one wavelength of
ultraviolet light. Employing Gambusia affinis to evaluate
the effect of different light treatments on toxicity to a fish
model, “photoinactivation’’ of the toxin(s) was reported
and such observations were not affected by the presence
of cells, cell pigments, oxygen or glutathione (Parnas
et al., 1962). Thus, it appears probable that photolysis of
the prymnesins occurred, which reduced the concentration
of bioavailable toxins, reduced toxin(s) exposure
to fish and thus reduced the magnitude of observed
aquatic toxicity. An understanding, however, of natural
sunlight influences on the stability of toxins produced by
P. parvum and associated aquatic toxicity is lacking.