Ecologically relevant effects of pulse application of copper on the limpet Patella vulgata

Along with habitat loss and climate change, anthropogenic inputs to the biosphere represent major threats to biodiversity; unfortunately, many of the studies necessary to understand these potential impacts have been carried out in laboratory systems with little or no ecological relevance. Understanding the impact of contaminants is dependent on the knowledge of their ecological consequences in the environment rather than reliance on laboratory studies. We assessed the impact of pulse contamination of copper on the behaviour and physiology of the limpet Patella vulgata L. on rocky shores. Toxicological methods were used in conjunction with ecological methods to elucidate possible effects of copper on cellular viability and phagocytosis (measures of cellular and immunological health), tenacity and grazing behaviour of P. vulgata. Exposures lasted for 10 d, and were replicated on 2 shores, and at 2 times. Ecological effects were assessed by the deployment of wax discs to quantify grazing intensity of contaminated limpets during this period. We also tested the effects of copper on tenacity as a measure of vulnerability to predators or to wave action. Phagocytic activity was unaffected by the addition of copper, as was the grazing intensity of P. vulgata. Tenacity was significantly reduced due to the copper pulse exposure, as was cellular viability. Copper significantly affected cellular viability; this was also reduced, although to a lesser extent, in limpets sampled from control plaster block replicates, suggesting unidentified influences from the plaster itself. Copper levels were significantly elevated in limpets sampled from the copper treatment, suggesting this as a useful method of toxicant dosing in the field. Ecological effects were mixed. There was no change in grazing intensity, but a significant reduction in tenacity, with implications for limpet mortality and thus rocky shore ecosystem processes.