What Are the Characteristics of Oil Spills?

Oil spills can severely damage marine environments and can cost millions of dollars to clean up. As of June 2011, the costliest oil spills ever recorded were the 1989 Exxon Valdez spill in Alaska and the BP oil spill in the Gulf of Mexico in 2010. Oil spills have several characteristics that make them a dangerous disaster; they can destroy an entire marine habitat if not cleaned immediately.

General Characteristics

• Different oil types have different effects in an environment -- each posing serious dangers. Oil floats in water due to a lower density; once it spills, it spreads thinly on top of the water, covering large surface areas. Although oil starts to weather and naturally decay, this breakdown takes a long time, meaning cleaning up spills as soon as possible is a necessity. The process of decay depends upon the type of oil, the place where it spills and weather conditions around the location.

Types of Oils and Their Effects

• The U.S. Fish and Wildlife Service (USFWS) categorizes oil types into five groups: very light, light, medium, heavy and very heavy. Although very light oils evaporate quickly, it is one of the most toxic substances when released into a marine environment. It can kill fish species, plants and other marine organisms on initial contact. Light to very heavy oils can cause long-term contamination to any type of environment, with medium to very heavy oil causing major harm and contamination. It affects all types of animals commonly found in water and can kill waterfowl and other animals, such as seals. Cleaning up these types of oil spills takes a lot of time and often costs millions of dollars.

Effects on Marine Habitat

• Marine life suffers from oil spills in several ways: through ingestion, inhalation, absorption and physical contact. Plankton is the first to suffer, and life-forms feeding on it get contaminated through ingestion. Larger fishes and other mammals that feed on fish get contaminated as well, potentially including humans who may consume contaminated fish. If the oil spill is sheltered in calm water, it can survive in the ocean for a very long time. This long-term contamination can change the ecological structure of the area and potentially even permanently destroy the habitat of marine animals.

Effects on Marine and Animal Life Forms

• Oil spills can kill off entire species of plants, but some species of algae can thrive. Marine plants can survive oil spills if cleaned up immediately. Invertebrates and fish that get contaminated, either through physical contact or through ingestion, get poisoned, usually killing off species that come into contact with the spill. Some species easily die off, while others survive with severe biological complications. Some fish contaminated with oil might survive, but become sterile. Birds and marine mammals, such as seals and sea lions, initially get contaminated through physical contact. Oil negates the insulating properties of feathers and furs, often causing animals to die of cold. Medium to heavy oils also cover these animals with a heavy, slick residue, impeding their movement and their ability to swim. Land animals who feed off the carcasses of these dead animals also get contaminated.