Effects of Simultaneous Exposure to Petroleum Hydrocarbons, Hypoxia, and Prior Exposure on the Tolerance and Sublethal Responses of Marine Animals: Blue Crabs and Killifish

摘要

Coastal Louisiana has been impacted by oil field activities for the last half century and the waters over the continental shelf west of the Mississippi River delta are also subject to extensive periods of hypoxia during the summer months. The determination of 28 day tolerance and RNA:DNA ratios, EROD activity growth condition (K) and the liver-somatic index have been used as sublethal biomarkers have been used to assess the effects of gradients of oxygen tension and the WSF of South Louisiana crude oil alone and in concert were determined for juvenile blue crabs and lesser blue crabs (tolerance and RNA:DNA ratios only) and the Gulf killifish. Chronic exposure to sublethal concentrations of the WSF of crude oil leads to increased tolerance and condition of the Gulf killifish when exposed to the WSF of South Louisiana crude oil. Exposure to the WSF under hypoxia produces slight increases in sensitivity to crude oil in comparison with exposure under normoxia. Blue crabs and lesser blue crabs are not as sensitive to the additive effects of hypoxia and the WSF of South Louisiana crude oil or to prior exposure history. RNA:DNA ratios are not a sensitive indicator of sublethal WSF stress in the Gulf killifish, the blue crab or the lesser blue crab. EROD activity, as an indicator of Cyctochrome p-450 induction increases in a dose related manner in the liver of Fundulus grandis from both locations on both a specific activity and total liver activity basis. Fundulus grandis exhibits enhanced adaptations to chronic petroleum hydrocarbon exposure but neither juvenile Callinectes sapidus nor Callinectes similis exhibit enhanced adaptation to petroleum hydrocarbons with chronic exposure.