Dynamic of intoxication and detoxification in juveniles ofMytilus chilensis(Bivalvia: Mytilidae) exposed to paralytic shellfish toxins

Abstract

Juveniles of the mussel Mytilus chilensis were exposed to a diet containing paralytic shellfish poisoning (PSP) toxins produced by the dinoflagellate Alexandrium catenella (strain ACC02). The feeding behaviour and the dynamics of intoxication and detoxification were evaluated over an intoxication period of nine days, followed by a detoxification period of eight days. A significant reduction in the feeding activity was measured during the first days of exposure to the PSP toxins (days 0 and 2), followed by a period of recovery observed on days 5 and 9, when the clearance rate of the contaminated mussels significantly increased. During the detoxification period, the contaminated bivalves showed a total recovery of clearance rate, and no significant differences were observed between contaminated and control groups. The intoxication dynamic was characterised by a rapid and sustained increase in the amount of PSP toxins accumulated in the tissues of the bivalves. Due to this increase, the level of PSP toxins critical for human consumption was reached on the first day, and at the end of the intoxication period, the mussels had accumulated 1601 μg STX eq. 100 g-1 tissue. During the detoxification period, a decrease of PSP toxins was observed, down to 319 μg STX eq. 100 g-1 tissue. The lower clearance rates observed over the first days of exposure would produce a decrease in the energy intake and could affect the rate of growth of juveniles. Despite this initial effect, the rapid intoxication capacity of M. chilensis corroborates that this species is a good indicator for the early detection of harmful algal blooms.