Oil spills can happen in a number of ways, including the mishandling of oil pipes and tankers. Their profound affect on the marine environment has been carefully documented, in no small part due to famous spills like the Exxon Valdez in 1989. Oil spills affect marine life in a variety of ways, and without intervention on the part of scientists and ecologists, the marine environment may have a slow recovery time.
In addition to prominently profiled sources of oil spills and oil slicks, a lot of oil enters the marine environment through day-to-day human activity. Storm drains, for example, collect a great deal of oil waste from the streets and pass it on to the world's oceans. Spills can also occur due to natural seepage from oil bearing areas. The most dangerous type is one that dumps a large amount of oil all at once, overloading the ability of the ocean to process it. These large oil spills affect marine life very negatively.
When oil is spilled, most of the volatile compounds evaporate quickly. The oil, however, remains floating on the surface of the water, and starts to disperse, forming a very thin film that can cover large areas of water. Marine life that lives, hunts, or travels in the area covered with oil can be affected. Different types of marine life are impacted differently, depending on their physiology and habits. The compounds left behind after the volatile compounds play a large part in why oil spills affect marine life, since many of them are toxic, dense, and bioaccumulative.
One of the most direct ways in which marine life is affected by oil spills is by essentially suffocating plants and animals. Marine plants can be covered in a film of oil which prevents oxygen and water exchange, causing the plants to die. Marine life which feeds on this vegetation will in turn struggle to survive. Coatings of oil on the flesh of birds and mammals can literally kill them through suffocation. Oil spills also affect marine life such as birds by stripping the water resistant coating from their feathers. A bird weighed down by oil may have difficulty flying, and will develop hypothermia as a result of exposure to extremely cold water. Mammals also suffer, as oil can remove water resistant compounds from the coats of furred marine life like otters and seals.
Oil spills affect marine life like filter feeders by concentrating in the flesh of these animals. Clams, mussels, and oysters may quickly accumulate toxins, which can kill the animals or be passed on along the food chain. Human consumers often complain that shellfish harvested from an area impact by an oil spill taste heavy and oily. Animals that rely on these filter feeders for food may become sick and die as a result of consuming them. Oil spills usually affect marine life at multiple levels of the food chain, and require a lot of work to fix the problem.
The inhalation and ingestion of compounds related to oil spills can also harm marine life, both in the long and short term. In the long term, oil spills interfere with the ability of marine life to breed, reproduce, grow, or perform other vital functions. Toxins in oil can also cause cancers and other illnesses in the long term. If left untreated, the area around an oil spill can be denuded of life. Fortunately, there are ways to clean up oil spills. In addition to chemicals, ecologists also use bacteria which thrive on the compounds in oil to digest it and render it less harmful.