The toxic effect of natural populations of G. corsicum
on seabream was confirmed in the present study.
The threshold concentration of toxic cells inducing
fish mortalities was found to be 366 cells ml−1, that
is the value of NOEC at the end of the event. Consistent
LD50 values were measured on different dates,
yet the increase in toxicity observed over the time indicates
a possible influence of environmental factors
on toxic activity.