Within the framework of a biosurveillance of the marine species on the Tunisian coasts, we studied the Sarpa salpa (L), a fish that is consumed by the people living in this region. There is a seasonal occurrence of hallucinogen effects observed when this fish is consumed by humans. The objective of this work was to correlate the antioxidant response of fish to environmental toxic phytoplanktons and metal exposure. The salema that lives around the Island of Kerkennah is primarily an herbivorous fish during all seasons. We observed an increased expression of catalase (CAT) and glutathione peroxidase (GPx) in certain organs compared to the control fish, D.annularis. There was a “season-depending” cumulative effect, appearing in the organs starting with the liver, followed by the brain, and finally the muscle. Moreover, it increases according to the size of the animal and thus to the amount of food it consumes. The hallucinogen effect that the consumption of S.salpa has on humans is parallel to the seasonal variation in the epiphytes that are co-ingested by these fish with their food. Furthermore, heavy metals accumulation in organs of these fish showed a significant variation between the two species (P<0.05). A significant correlation (P<0.01) was also observed between the total toxic dinoflagellates and the antioxidant response: CAT and GPx in liver, brain, and muscle for all seasons and all sizes together. Our work indicates that, toxic phytoplanktons and heavy metals accumulation are responsible for the increase of antioxidant activities in the organs of S. salpa.
