Fluoranthene-induced histological alterations in oysters, Crassostrea virginica: Seasonal field and laboratory studies

Stress-related histological parameters (digestive epithelial thickness, gonadal area, incidences of helminth parasites and hemocytic infiltration, and parasite intensity) were monitored seasonally in the visceral mass of oysters, Crassostrea virginica, collected from an undeveloped site (Clambank Creek, North Inlet estuary, SC) and two urbanized, fluoranthene-contaminated sites (Parsonage Creek and Marina pipe, Murrells Inlet estuary, South Carolina). Reduced mean epithelial thickness and an elevated incidence of hemocytic infiltration was occasionally observed in the Murrells Inlet oysters. Correlation analysis revealed that the seasonal profile of mean epithelial thickness in the Parsonage Creek oysters was related to that of their body burdens of fluoranthene and six other polycyclic aromatic hydrocarbons. Oysters exposed to fluoranthene in the laboratory also exhibited a reduction in their mean digestive epithelial thickness, and this response was dependent upon the interaction between fluoranthene body burden and exposure time. These results suggest that thinning of the digestive epithelium is a useful histological indicator of fluoranthene-induced stress, and demonstrate the utility of seasonally monitoring several stress-related histological parameters in conjunction with contaminant body burdens.