Keynote: Oil Spill Disasters and Chronic Responses of Fish: Lessons from Exxon Valdez to Deepwater Horizon

Following the Exxon Valdez oil spill in 1989, effects of the oil on Pacific herring were documented at various life stages. Eggs from reference sites and those considered exposed to oil were incubated in the laboratory and examined for abnormalities within 24 hours  after hatch. Significant morphological and cytogenetic alterations were seen and these were correlated with polyclic aromatic hydrocarbon (PAH) levels in mussels collected from the same areas. These field studies were confirmed in laboratory controlled exposures with the same life stages. In adult Pacific herring, histopathological alterations were observed. Certain of these were consistent with host response to stressor exposure but were confounded by finding of disease , viral hemorrhagic septicemia, the expression of which can be induced by dose-dependent exposure to weathered crude oil. Investigations at the population level reflected exposure. These lessons from Exxon Valdez as well as others will be reviewed and what they teach us about how to proceed will be covered in detail. Encouragement is warranted due to the 20 year refinement of our toolkit for integrative evaluation of environmental toxicant exposure effects. However, multifactorial issues of volume of oil spilt, variations in oil composition, dispersant(s), different assemblages of species with differing life histories, environmental factors such as hypoxia and  temperature as well as the distance from site of spill to shore will need to be added to lessons from Exxon Valdez as we seek to define natural resource damage and assess effects/responses.