How Do Oil Spills Affect Fish?
Environmental Factors
Large oil spills can kill fish directly by suffocation and can also destroy the surrounding environment where fish lay eggs and young fish develop. Direct exposure to crude oil causes a coagulated mucous film to cover the body and gills.
Oil also disperses in water, and chemicals in the oil are absorbed by fish and can cause death. Oil disperses more quickly in warm water, and the hazards diminish over a shorter period, but the toxicity can be more intense. Oil spills in cold water disperse more slowly, but the toxicity can last for many years. Spills in rivers and streams disperse the oil by agitation and are similarly more toxic to fish.
Containment booms are used to keep the spill from spreading while emergency measures are taken to pump the spilled oil back into tankers. Modern oil tankers are required to have double hulls to reduce the likelihood of hull penetration in collisions and accidental groundings.
Toxicity to Fish
Crude oil contains many compounds that are toxic to animals including fish. Polycyclic aromatic hydrocarbons (PAH) in crude oil affect eggs and larvae of fish and increase mortality. These compounds are difficult to dissolve in water, but wave action and large amounts of crude oil will cause the compounds to be present at toxic levels. Fish are particularly susceptible to absorbing these compounds because they naturally have a high oil or fat content, and the compounds dissolve easily into their tissues through contact with the skin and gills.
The effects on fish larvae range from mortality to abnormal development and deformities. Since the effects of untreated oil spills can last for years, they can have a devastating effect on local fish populations.
Cleanup Measures
Cleaning up spills sometimes involves using a detergent to disperse the oil. Detergent makes the oil more soluble in water. This reduces the amount of time that the spill affects wildlife such as birds and mammals. Unfortunately, it also makes the oil more easily absorbed by fish and is very toxic, particularly to young fish.
Crude oil "weathers" naturally, turning into tar that is less harmful. Natural oil seepage also occurs in areas around the world including the West Coast of North America. Beach goers are aware of the black gobs of tar that they avoid stepping in; these are relatively harmless, but difficult to remove.
Related posts
Oil spills are major ecological disasters.An oil spill is one of the most severe ecological disasters that can happen. The reasons for this are the difficulties in cleaning oil from water and the...
Types and Effects of Oil SpillsTwo types of oils can be spilled in the ocean or near coastlines: refined oils and crude oil or bunker fuels. These will have vastly different effects on the surroun...
Effects of Oil Spills on FishThere are many different ways that an oil spill can affect marine life. The U.S. Fish and Wildlife Service indicates that the seriousness of the situation depends upon...
Oil spills devastate marine ecosystems.Heartbreaking images of birds and sea mammals, coated with tar-like substances and struggling to stay afloat in oil-slicked surf, graphically portray the imm...
Oil Kills Coral ReefsCoral reefs can be killed off by direct exposure to oil. Intertidal corals are the most vulnerable, since oil on the surface of the water is deposited directly on the coral re...
