Metal Concentrations in Tissues of American Lobsters (Homarus americanus, Milne-Edwards) with Epizootic Shell Disease

Abstract

Environmental contaminants have been suggested frequently as causative factors in crustacean shell disease. This study explored the relationship of environmental contaminants to epizootic shell disease in the American lobster (Homarus americanus). Trace metal loads were analyzed in lobsters showing signs of shell disease and those without signs of shell disease collected from Narragansett Bay, Rhode Island Sound, and Long Island Sound in 2007. In addition, trace metals were analyzed in lobsters collected in 2008 from a single station in Narragansett Bay and a reference site in Maine for a multiparameter, multiinvestigator study (the “100 Lobsters” project). Analyses focused primarily on hepatopancreas and hemolymph tissues, but muscle, shell, gills, and ovaries were also analyzed to examine the partitioning of metals between various component tissues. Sediment from the “100 Lobsters” collection site was also analyzed. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure 10 different contaminant elements, including arsenic, cadmium, cobalt, chromium, copper, manganese, molybdenum, nickel, lead, and vanadium. Mercury was determined using a direct mercury analyzer. Overall, there was no systematic difference seen in contaminant metal burdens between those lobsters with signs of shell disease and those without signs, and hepatopancreas concentrations were generally similar to other reported values for field-collected lobsters. Contaminant metals were found to be partitioned between tissues differentially. Hepatopancreas tissue generally contained the greatest concentrations of contaminants, but exoskeleton contained the highest levels of manganese, nickel, and lead. Sediment collected from the “100 Lobster” sampling site showed that concentrations of several metals were similar to or exceeded the suggested sediment quality guidelines, consistent with a site that is moderately impacted by metals. Based on these data, the presence or absence of shell disease cannot be attributed to the magnitude or patterns of metal accumulation and disposition.