Metal concentrations and detoxification mechanisms in Solea solea and Solea senegalensis from NW Mediterranean fishing grounds

The common sole, Solea solea and the Senegalese sole, Solea senegalensis are two important commercial species that coexist in the NW Mediterranean Sea. The present field survey was designed to assess the role of kidney in metal handling and detoxification in the two sole species collected at six fishing grounds along the Catalan coast. Metallothionein (MT) and selenium (Se) were analysed in relation to toxic metal loads in kidney as potential protective mechanisms. Acetylcholinesterase (AChE) and lactate dehydrogenase (LDH) activities as well as lipid peroxidation (LP) levels were measured in several tissues as general markers of toxicity. AChE was measured in brain muscle and gills, LDH in plasma and LP in muscle and gills. The protective role of MT and Se was indicated by the positive correlations with Hg and Cd levels as well as with the high Se:Hg ratio, in a species-dependent way. Principal Component Analysis (PCA) considering all chemical and biomarker variables discriminated individuals collected at the different fishing grounds.