Use of biomarkers to evaluate the effects of environmental stressors on Mytilus galloprovincialis sampled along the Moroccan coasts: Integrating biological and chemical data.

A biomonitoring study using wild Mytilus galloprovincialis mussels sampled from six sites along the Moroccan coasts evaluated whether select biomarkers are suitable for identifying and quantifying pollution-induced stress syndrome in mussels. Lysosomal membrane stability was confirmed to be a highly sensitive biological parameter, and acetylcholinesterase activity was found a suitable biomarker of neurotoxicity. Metallothionein concentrations were in line with heavy metal concentrations detected in mussel tissues. However, malondialdehyde was not sensitive, suggesting the need for alternative biomarkers of oxidative stress. Three different approaches were used for biomarker and chemical data integration. The Integrated Biomarker Response (IBR) was suitable for classifying the stress response but did not allow to evaluate the level of stress in the organisms. The Mussel Expert System (MES) was suitable for ranking the biological effects of pollutants, also providing an indication of the evolution of the stress syndrome in the animals. Finally, the use of Principal Component Analysis (PCA) provided indication of the inorganic chemicals contributing to the detrimental biological effects.

Valve movement response of the mussel mytilus galloprovincialis to metals (Cu, Hg, Cd and Zn) and phosphate industry effluents from Moroccan Atlantic coast.

Valve activity was measured in the Mediterranean mussel Mytilus galloprovincialis in response to sublethal concentrations of four metals (Hg, Cu, Zn and Cd) and two phosphate industry effluents from the Atlantic coast of Morocco. Valve movements were monitored using a proximity inductive sensor which could display all activity figures from full closure to wide opening of the shell valves. In a 1 h exposure experiments, all metals induced a decrease in the time of normal opening and the appearance of sequences of stress behaviour, including enhanced valve adductions and complete closure at high concentrations. Mercury (tested from 5 to 75 microg Hg l(-1)) was the most toxic to the valve activity, with a threshold effective concentration at 10 microg Hg l(-1) and full valve closure occurring at 50 microg Hg l(-1). Copper (15-150 microg Cu l(-1)) showed a toxic effect starting at threshold concentration of 20 microg Cu l(-1) and induced full valve closure at 150 microg Cu l(-1). Zinc (100-500 microg Zn l(-1)) was effective in reducing the time of normal opening (threshold concentration at 100 microg Zn I(-1)) but no complete closure was recorded in any of the tested concentrations. For cadmium (1000-5000 microg Cd l(-1)), the valve activity was insensitive for exposures under 2000 microg Cd l(-1). Results for the testing of several samplings of the phosphate industry effluents (Safi and Jorf Lasfar) showed that their toxicity varied over the time. The effluent of the Jorf Lasfar plant (2-9.4%) was, however, more toxic than that of Safi (1-25%). In the light of these results, the sensitivity of the valve activity of Mytilus galloprovincialis to pollutants and its usefulness for in situ monitoring of coastal pollution in Morocco are discussed.

Quantification of metallothionein-like proteins in the mussel Mytilus galloprovincialis using RP-HPLC fluorescence detection.

A HPLC-fluorescence method, using the fluorophore SBD-F (ammonium-7-fluorobenz-2-oxa-1,3-diazole-4-sulfonate), was adapted for the quantification of metallothioneins and their isoforms from the Moroccan mussel Mytilus galloprovincialis. The method was first optimized using a rabbit liver metallothionein. The effects of EDTA, tris(2-carboxyethyl)phosphine, and SBD-F on the labeling efficiency were studied. The optimized method was then applied to evaluate the amount of metallothionein in the mussels either exposed to cadmium in the laboratory or collected from the Casablanca coast, Morocco. The concentrations of metallothioneins measured in the field samples describe the degree of contamination of the sites and are reflected by distinct isoform patterns.