The Effects of Oil on Wildlife

We have all seen pictures and videos of wildlife covered in black, sticky oil after an oil spill.  These pictures are usually of oiled birds.  Many people are not aware that it is not just birds that get oiled during a spill.  Other marine life such as marine mammals can also suffer from the effects of an oil spill.  Even small spills can severely affect marine wildlife.

Not all oils are the same.  There are many different types of oil and this means that each oil spill is different depending on the type of oil spilt.  Each oil spill will have a different impact on wildlife and the surrounding environment depending on:

Oil affects wildlife by coating their bodies with a thick layer.  Many oils also become stickier over time (this is called weathering) and so adheres to wildlife even more.  Since most oil floats on the surface of the water it can effect many marine animals and sea birds.  Unfortunately, birds and marine mammals will not necessarily avoid an oil spill.  Some marine mammals, such as seals and dolphins, have been seen swimming and feeding in or near an oil spill.  Some fish are attracted to oil because it looks like floating food.  This endangers sea birds, which are attracted to schools of fish and may dive through oil slicks to get to the fish.

Oil that sticks to fur or feathers, usually crude and bunker fuels, can cause many problems.  Some of these problems are:

Oil does not have to be sticky to endanger wildlife.  Both sticky oils such as crude oil and bunker fuels, and non-sticky oils such as refined petroleum products can affect different wildlife.  Oils such as refined petroleum products do not last as long in the marine environment as crude or bunker fuel.  They are not likely to stick to a bird or animal, but they are much more poisonous than crude oil or bunker fuel.  While some of the following effects on sea birds, marine mammals and turtles can be caused by crude oil or bunker fuel, they are more commonly caused by refined oil products.

Oil in the environment or oil that is ingested can cause:

  Animals covered in oil at the beginning of a spill may be affected differently from animals encountering the oil later.  For example, early on, the oil maybe more poisonous, so the wildlife affected early will take in more of the poison.  The weather conditions can reduce or increase the potential for oil to cause damage to the environment and wildlife.  For example, warm seas and high winds will encourage lighter oils to form gases, and will reduce the amount of oil that stays in the water to affect marine life.

The impact of an oil spill on wildlife is also affected by where spilled oil reaches.  For example, fur seal pups are affected more than adults by oil spills because pups swim in tidal pools and along rocky coasts, whereas the adults swim in open water where it is less likely for oil to linger.  Dugongs als feed on seagrass along the coast and therefore be more affected by oil spills.

Different resources will be needed to combat an oil spill, depending on the number and type of wildlife that is affected.  Quick and humane care of wildlife affected by oil spills is required by law.  The National Oiled Wildlife Response guidelines [PDF Icon PDF: 126 Kb] have been developed at both the Commonwealth and State/Territory level under Australia's national strategy to respond to oil and chemical spills in the marine environment.  This strategy is known as the National Plan to Combat Pollution of the Sea by Oil and other Noxious and Hazardous Substances (National Plan).