Effects of molting and environmental factors on trace metal body-burdens and hemocyanin concentrations in the American lobster, Homarus americanus

Abstract

Hemocyanin concentrations in the hemolymph of marine crustacea are dependent on the molt cycle and on environmental conditions. Studies in our laboratories have found that hemocyanin levels in blue crabs are reduced after ecdysis and under conditions of environmental stress (Engel, Brouwer, & McKenna, 1993. Hemocyanin concentrations in marine crustaceans as a function of environmental conditions. Marine Ecology Progress Series, 93, 233–244). We have extended those studies to include the American lobster, Homarus americanus. Hemolymph and digestive gland tissues from Long Island Sound lobsters were analyzed for hemocyanin, copper, and zinc during different stages of the molt cycle. Hemocyanin, copper and zinc in the hemolymph were highest in premolt stages (D 1–D 4), and lowest in the postecdysal papershell stages (B 1–B 2). Concomitantly, copper in digestive glands decreased significantly following ecdysis, but no significant changes in the metals bound to metallothionein (MT) were observed. Copper-MT was the predominant form throughout the molt cycle, presumably because lobsters were obtained from copper-contaminated areas. To examine the effects of environmental factors, intermolt lobsters were collected from locations of different environmental quality along the Atlantic coast, and were analyzed for hemocyanin and trace metals. In general, animals from areas with a history of contamination showed the highest hemocyanin concentrations.