Comparison of embryonic development and metal contamination in several populations of the sea urchin Sphaerechinus granularis (Lamarck) exposed to anthropogenic pollution.

Over the past years the functional deficiencies observed in the sea urchin Sphaerechinus granularis from the Bay of Brest (France) have led us to select several populations within this species to assess water quality in the Bay of Brest. The present study reports on the comparison of the quality of embryonic development and of the level of metal contamination in sea urchin gonads and gut wall in four populations. Three of them lived in the Bay of Brest, and the last one was considered a reference, being settled in the Glénan Archipelago in southern Brittany (France). The sea urchin population living at the mouth of the River Aulne, at the Armorique Point, seemed to be the most affected, for it displayed the highest rate of blockage and the longest delay in embryonic development along with the highest concentrations in heavy metals, i.e., Fe, Cu, Pb, Cd, and Hg, in the gut wall and in the gonads. A comparison with previous data highlighted a degradation of health conditions in the population living at Marloux in the vicinity of Brest harbor. The comparison of the metal levels detected in individuals from these two populations with the data reported in the literature allowed us to conclude for a local contamination of the bay waters by Fe and Hg. In addition, this study also revealed that Zn and Cd concentrations were sometimes higher than the maximum values reported in the literature and evidenced an increase of contamination by Cu and Pb over the period of study; it should be noted, however, that these values were not excess levels. Our investigations also suggest that Zn, Cd, Pb, and Cu levels should be monitored in the future.