Kepone-induced scoliosis and its histological consequences in fish.

Scoliosis in fish is caused by several diverse agents that possibly act on the central nervous system, neuromuscular junctions, or ionic metabolism. The organochlorine pesticide Kepone induces scoliosis in the sheepshead minnow. Some effects associated with Kepone-induced scoliosis in these fish are disruption of myotomal patterns, inter- and intramuscular hemorrhage, fractured centra of vertebrae, and death. The histological syndrome of Kepone poisoning in fish and the clinical syndrome in humans suggest that the nervous system is a primary target for Kepone and that scoliosis is a secondary effect of Kepone poisoning in fish.

Relationships between tissue contaminants and defense-related characteristics of oysters (Crassostrea virginica) from five Florida bays.

Evidence linking bivalve defense responses with pollutant exposure is increasing. Contaminant effects on immune or defense responses could influence the ability of an organism to resist infectious disease. This study explored relationships between xenobiotic chemicals accumulated in oyster (Crassostrea virginica) tissue and various measures of putative oyster internal defense activities and physiological condition. Defense-related and physiological measurements were made on individual oysters collected from 22 sites at five Florida bays and pooled oyster tissue from each site was analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and certain pesticides. Chemical concentrations, physiological condition, and hemocyte and hemolymph characteristics varied across bays and among sites within a bay. Within-bay comparisons showed that sites with high oyster defense-related activities often had accompanying high tissue concentrations of one or more classes of xenobiotic chemicals. Correlation analysis performed across bays demonstrated significant positive relationships between most defense-related characteristics and at least one contaminant, including various PAH, PCB and trace metal analytes. In combination with other recent studies, these results strengthen the hypothesis that certain xenobiotic chemicals may be associated with elevated oyster hemocyte activities, even though the ultimate influence on disease resistance remains unknown.

A survey of oysters Crassostrea virginica from Tampa Bay, Florida: associations of internal defense measurements with contaminant burdens.

Oysters from 16 sites in Tampa Bay, Florida, were collected during a 6-week period in winter 1993 and analyzed for both biological characteristics and tissue chemical concentrations. Using previous sediment contamination and toxicity data, oyster tissues from the selected sites were expected to exhibit a wide range in both quantity and type of chemicals. Chemical analysis showed tissue concentrations at some of these sites to be greater than national averages, as reported by the National Status and Trends Mussel Watch Program, for total PAH, total PCB, total chlordanes, DDT, Cu, Pb and Zn. Measures of oyster internal defense, including hemocyte density, rate of locomotion and superoxide generation, varied significantly among sites and were generally higher at sites with higher tissue concentrations of xenobiotic chemicals. Potential associations between oyster defense characteristics and accumulated chemical contaminants, either singly or in chemical classes, were explored using correlation analysis and a composited ranking procedure. Positive relationships were found for hemocyte characteristics with certain trace metal (Cu, Sn and Zn) and PAH analytes, whereas negative relationships were found with certain PCB and pesticide analytes. Heightened defenses in contaminated conditions may reflect a hemocyte process for sequestration and detoxification of environmental contaminants. Oysters from four of the 16 sites were additionally collected in June and September 1993 and site-related differences did not closely parallel those obtained in winter. Seasonal environmental factors may have altered contaminant-related differences among sites.