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Oil Spill Biology 1. Impacts 2. Cleanup Ned Black, Ph.D., CERCLA Ecologist, U.S. EPA Region 9 415-972-3055 [email protected] 1. IMPACTS (aka Ecological Risk Assessment or Natural Resource Damage Assessment) Stressors Ecological Receptors Measures of Exposure/ Impact Unacceptable Risk/Damage Contaminants, e.g., bunker oil Birds, otters, fish, eel grass Evidence there is or might be a problem Someone should pay for cleanup or damages Ecological Risk Assessment Fundamentals COCs and receptors present, but COCs not bioavailable or concentrations too low Contaminants of concern COCs at demonstrably toxic concentrations, but exposure pathway to receptors incomplete, e.g., Mansfield Canyon mining district Measures of Exposure/ Impact Potential Receptors Potential receptors impacted by something other than COCs, e.g. habitat destruction and industrial contamination along Gulf Coast Ecological Receptors • Charismatic macrofauna • Eel grass, pickle weed, barnacles, herring roe Impacts • Acute and chronic toxicity of fuel in water column: mortality to plankton (including larvae of many species); narcosis effects to juvenile fish at ultra-low concentrations • Population-level effects: Cosco Busan spill decimated 2007 herring reproduction due to oiling of roe on piers • Smothering of marsh and tidal plants • Oil-coated animals: hypothermia, poisoning from ingesting oil during preening or from eating contaminated food 2. Cleanup (aka Biodegradation) • Global carbon cycle: bacteria and fungi mineralize complex organic molecules • Bacteria and fungi have been doing this for 4.5 billion years • Bacteria and fungi are everywhere (including water puddles inside gas pipelines) • Bacteria will attach to an oil/water interface and consume hydrocarbons as they slowly dissolve into the water • Dispersing oil into tiny particles speeds this process Ripley, M. , Harrison, A. , Betts, W. and Dart, R. (2002), Mechanisms for enhanced biodegradation of petroleum hydrocarbons by a microbe-colonized gas–liquid foam. Journal of Applied Microbiology, 92: 22–31. Figure 7. (a) Phase contrast (100×); (b) fluorescence (40×) and (c) confocal scanning laser (40×) photomicrographs illustrating the sorption of Acinetobacter junii (Hex-2) at the gas–liquid interface of the foam. L, Lamellae; P, plateau border; B, bacteria; G, gas bubble Mansfield Canyon Mining District, AZ Shaft pool