Abstract:
Estuaries and lagoons in Sri Lanka are increasingly threatened by
anthropogenic pollution. Cholinesterases (ChEs) of bivalves inhabiting these
brackish water bodies may be used as ecotoxicological waming signals of the
occurrence and effects of aquatic pollution. The present study was undertaken to
characterize the biochemical properties of ChEs in the gill tissues of two bivalves,
Crassestrea madrasensis and Anadara antiquata using different substrates and
selective inhibitors. In addition, sensitivities of gill ChEs of these bivalves to selected
aquatic pollutants viz, Cadmium and Copper (heavy metals) and Chlorpyrifos (an
organophosphate insecticide) were assessed.
Responses to specific substrates and inhibitors suggested the presence of
two types of ChEs viz. Acetylcholinesterase and Butyrylcholinesterase in the gill
tissues of both species. Dose dependent inhibition in the enzyme activ ies was
observed in response to in vitro exposure to Copper and Cadmium and in vivo
exposure to Chlorpyrifos. Both species showed similar sensitivity to the tested
heavy metals. However gill ChEs of Anadara antiquata were more sens ive to
Chlopyrifos exposure than that of the other species. In conclusion, gill
cholinesterases in the two bivalve species have a potential as biomarkers for
mon oring neurotoxic polluants in brackish water bodies in Sri Lanka .
