Intra-specific variation in cardiac activity of the Mediterranen limpet Patella caerulea along a contamination gradient.

The Mediterranean limpet Patella caerulea was collected along a gradient of metal pollution. On the basis of monitoring data released by the Regional Agency for Environmental Protection of Tuscany, the following four sites range from strongly polluted to unpolluted: Porto di Livorno (PL), Marina di Pisa (MP), Quercianella (Q) and Castiglioncello (C). Measurements of body concentrations of copper and zinc - the two metals eliciting cardiac variations in limpets - confirmed that the four sites lie along a gradient of metal bioavailability. Non-invasive recordings of cardiac activity showed that bradycardia induced by copper (0.25 and 0.5 mg l(-1); up to 6 hr) was higher in limpets from Q and C than in those from PL and MP. These results suggest that the cardiac response to copper can be used to assess the degree of exposure of native limpet populations to trace metals.