Oil spills from ocean-going vessels have long been an alarming environmental hazard. However, inland oil spills have a more immediate effect on the human environment and the quality of human life due to the effects of these spills on drinking water, water fowl, and fish. The project being proposed here will look at the toxicity of low-grade diesel fuel on the fertilization process, and on early embryogenesis in the sea urchin, Arbacia punctulata. It is hoped that valuable information will be gained as to the probable effects of these hydrocarbon fuels on reproduction and growth of aquatic organisms. The reproductive toxicity of low-grade diesel fuels can be studied in this invertebrate without the concerns that accompany the conduct of toxicity studies in vertebrate animals.