The oiling of marine wildlife is generally not a natural occurrence. Although there are places in the world where oil comes out of the sea floor as a natural geological phenomenon (natural seeps), in most cases marine wildlife becomes oiled as a result of an accidental or deliberate spill caused by man. Mitigating the effects of oil spilled into the environment and caring for oil affected wildlife can have significant positive effects on species and populations.
In recent times, incidents involving Hazardous and Noxious Substances (HNS) have seriously affected marine species. Thousands of birds coated in polyisobutylene washed up on the shores of the Netherlands and the UK in separate incidents. Unusual mass strandings of rare whale species have been linked to anthropogenic noise. Experienced oiled wildlife responders are facing new challenges in dealing with HNS spills but progress is being made. Responding to mass stranded marine mammals requires very different basic skills but the principles of preparedness, training and cooperation increase success rates in these incidents as well.
Wildlife at risk from oil spills
The extent to which oil spilled at sea may threaten or affect animals that live in the marine environment depends on the type of oil, the season, the place, the weather and sea conditions. The threat is a combination of how the oil behaves and where the vulnerable habitats and species are in relation to the oil.
Oiled wildlife response and preparedness is usually focused exclusively on specific macro-vertebrates, particularly sea and coastal birds, marine mammals (such as seals, sea otters, dolphins and whales) and marine reptiles (such as sea turtles).There are reasons why this is the case.
Coastal and seabirds, marine mammals and sea turtles:
- are dependent on the sea surface to rest, feed (birds and sea otters) and breathe (marine mammals, sea turtles) and therefore are particularly vulnerable to oiling.
- may wash ashore and, therefore, are the most visible victims of the oil spill. They are valued by the public, and considered ambassadors of the values of a healthy marine ecosystem as a whole.
- are common subjects of scientific research programmes, thus scientists have an interest in systematically collecting, counting and studying the dead and live animals to make a reliable impact assessment.
- may have protected, e.g. threatened or endangered, status if they are a species of national or international conservation value. In such cases the spill immediately attracts international attention. Animals found dead or alive will require specialised treatment, which will be an important consideration in the response plan.
- are picked up in some countries by specialised organisations who attempt to rescue, clean and rehabilitate them. These attempts normally receive strong support from the public.
Other marine animals
Marine animals that are less dependent of the sea surface (such as most fish species and most marine invertebrates) are less likely to be immediately affected by floating oil. When the oil does not float, or has been dispersed, it may affect marine creatures living in the water column or on the seafloor.
However the natural history and behaviour of fish and invertebrates do not allow any specific strategies or techniques by which their oiling in such cases can be prevented. Relatively few of these animals will wash ashore after their oiling and therefore do not require dedicated strategies or logistics as part of a wildlife response.
The impacts of oil on these animals is often felt quite some time after an oil spill event, when food species are found to be contaminated or when marine wildlife begins to suffer from starvation due to the loss of these key food species.