Cholinesterases activities and lipid peroxidation levels in muscle from shelf and slope dwelling fish from the NW Mediterranean: its potential use in pollution monitoring.

We selected muscle tissue from nine commercial fish species, seven teleosts and two elasmobranchs, frequently caught in the NW Mediterranean trawling grounds in two different habitats (the continental shelf at 53 m and the slope at 660 m) for cholinesterases (ChEs) characterisation and activities determination, as well as the measure of lipid peroxidation (LP) levels. Acethyl- (AChE), butyryl- (BChE) and propionyl- (PrChE) cholinesterase were chosen as exposure markers of neurotoxic chemicals/molecules and LP as an effect marker of oxidative damage. The use of diagnose inhibitors: eserine sulphate, iso-OMPA and BW284c51 confirmed the measurement of true ChEs as well as the presence of pseudocholinesterases. The present study has evidenced the existence of interspecies differences, especially between teleosts and elasmobranchs but not in relation to depth. Moreover, the good correlation observed between all ChEs in most of the studied fish, supports the use of AChE as neurotoxic marker in field pollution monitoring. The non-metric multidimensional scaling analysis identified the commercial species hake Merluccius merluccius, among teleosts, and the shark, Galeus melastomus, as more adequate sentinel species in commercial fishing grounds. AChE activity showed a relationship with the fish trophic level, while all ChEs revealed a relationship with the feeding habits (benthic, suprabenthic, pelagic) and the stomach fullness. BChE activity and LP levels were the only markers to show a relationship with their swimming capacity.