Toxic Prorocentrum lima induces abnormal behaviour in juvenile sea bass

Juveniles of the European sea bass Dicentrarchus labrax were exposed to both cell-free medium and whole cell cultures of the dinoflagellate Prorocentrum lima strain PL2V. Fish were also fed a commercial fish diet in tanks containing live P. lima, and Artemia that had ingested the alga. Fish exposed to the cell-free medium and to whole cell cultures were stressed and behaved abnormally when compared to the behaviour of control fish, fish in normal seawater. Stress-related behaviours included hyperactivities (jumps, fast let-right turns, surface swims, etc), poor feeding reflexes and abstinence from feeding. Fish that directly ingested the alga or that ingested Artemia containing the alga died. Histological studies revealed that gills and liver of treated fish were impacted, as opposed to the normal conditions of same tissues in control fish. The diseased organs could have been responsible for the abnormal behaviours and death of treated fish. The aquaculture and ecological implications of the results are discussed.