The Impact of Copper on Non-Indigenous and Native Species of Suspension-Feeding Bivalves in Mission Bay, San Diego, California

Native (Chione californiensis) and non-indigenous bivalve species [Musculista senhousia (now known as Arcuatula senhousia), and Venerupis philippinarum] were collected from Mission Bay, San Diego, California and exposed to copper contaminated water at estimated concentrations of 0 ppb, 25 ppb, and 50 ppb over the course of two experimental periods of 18 days and 12 days. Bivalves were placed in tanks in a temperature controlled environment, and measurements of a number of parameters were taken during and after the exposure to copper: survivorship, feeding rates, growth, mucus production, and tissue copper concentrations for the entire body, gills, and digestive tract. These factors were analyzed on their own and in comparison to tissue copper concentration to examine potential relationships. Observations indicated that there were several statistically significant differences, either between copper concentration groups, between species, or both. The majority of sublethal measures showed no statistically significant differences across both experiments, with the exception of whole body copper accumulation. Whole body copper accumulation showed significant differences between Musculista and both Chione and Venerupis, and may suggest a competitive disadvantage in copper contaminated environments, as Chione and Venerupis may be more efficient at removing copper from tissue. Other sublethal measures that did show significance did not show consistency across both experiments or showed contradicting trends, and none showed consistently significant trends when compared with tissue copper concentrations. Algae depletion rate measurements produced inconclusive results. The data indicates that most sublethal biomarkers used in this experiment were not indicators for copper toxicity for the species in this experiment at the tested concentrations, and that of those species, Chione was the most resistant to the effects of copper with respect to mortality and whole body accumulation