Biomarkers and contaminants in the bivalve Perna perna caged in coastal sites in Senegal

Abstract

There is a scarcity of model species for contaminant monitoring in Africa meanwhile several studies have reported cases of pollution by  numerous chemical contaminants. The aim of this study was to evaluate the use of one possible model species, the filter-feeding coastal  bivalve Perna perna, for contaminant monitoring. P. perna collected from an unpolluted area of the Senegalese coast were transplanted  to the Dakar harbour and to a reference location in the open coast in the vicinity of Dakar. Mussels were retrieved after four weeks’  deployment and either analysed immediately or allowed to depurate for another four weeks. Mussels were analysed for biomarkers  (selected transcripts and cellular responses) in gills and digestive gland (hepatopancreas), as well as for whole body residues of polycyclic  aromatic hydrocarbons (PAHs) and metals. Mussels held in the harbour had accumulated both PAHs and the metals Pb, Cu and  Se. Transcripts of biotransformation enzymes were downregulated whereas transcripts for antioxidant enzymes were upregulated in  the gills compared to those of mussels held at the reference location. Digestive gland acetylcholinesterase and lactate dehydrogenase  enzymatic activities were decreased compared to mussels from the reference location. Following depuration, gill transcripts had returned  to baseline level except for gill glutathione S-transferase and lactate dehydrogenase activity, which decreased.   Acetylcholinesterase inhibition was less prominent following depuration, but still significantly inhibited. The results suggest that caging of  P. perna and measurement of selected biomarkers can be used to monitor effects of coastal environmental contamination.