The effects on freshwater wildlife of chronic exposure to oil field discharges are not well known. Collections of wastewater, aquatic invertebrates, fish, salamanders, and small mammals were made in several streams in the oil fields of western Pennsylvania during 1980-81. Estimates of the petroleum content of two wastewater discharges were high (21.9 and 8.4 ppm) and one was low (0.3 ppm). Water conductivity was inversely related to aquatic invertebrate biomass. Hydrocarbons accumulated in significantly greater amounts in crayfish, fish, and small mammals from collection sites with oil extraction activity than from sites without oil extraction activity. Estimates of total petroleum in invertebrates, trout, and suckers averaged between 200 and 280 ppm for oil extraction sites and between 8 and 80 ppm for sites without oil extraction activity: Oil extraction activity did not affect metal accumulation by fish. Oil and wastewater discharges in oil fields disrupt community composition and can cause an overall reduction in stream productivity.
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Environmental contamination in the oil fields of western Pennsylvania