oils spills have been among the greatest human-induced environmental disasters ever. They have destroyed ecosystems, ruined beautiful landscapes, and have caused immeasurable economic loss. Spilled oil affects both marine organisms and animals which live near the coastline. It can decimate populations of certain species, and causes slow, agonizing deaths to others¹. There are a number of ways oil effects the environment. Probably the most well-known and publicised is the effect on mammals and birds who are unlucky enough to be caught in the area of a spill.
Oil sticks to hairy mammals such as seals and sea otters, and reduces their ability to insulate against the cold. This leaves them vulnerable to hypothermia, and is a major killer, especially in colder polar waters where even a tiny patch of oil is enough to cause death². It can also block up the blowholes and airways of whales and dolphins who surface through an oil spill, affecting their breathing and their ability to communicate while damaging sensitive internal membranes.
Seabirds which dive into or land on affected areas of ocean will become covered with oil. This can make flying difficult or impossible, which has a number of effects – affected birds are unable to escape from predators, are often unable to catch food because they are slower, and they spend more energy when flying. If oil reaches coastal areas, then it can contaminate nesting areas, causing parent birds to abandon their eggs. It also reduces the water-repellent effects of birds’ feathers. This reduces both their ability to insulate themselves against the cold and their flotation ability – causing a number of deaths from hypothermia, exhaustion from trying to stay afloat, and drowning³.
Sea turtles are air-breathing, and therefore must surface to breathe. If they surface in an oil slick, they may breathe in oil vapours and residues, which can cause huge respiratory and lung problems. If they accidentally ingest the oil or get it in their eyes, it damages their vision or their internal organs. As with birds, oil spills can affect coastal nesting areas, destroying eggs and wiping out juveniles and hatchlings. Young turtles face amplified risks since they drift with the currents, and will often congregate in the same places that spilled oil converges³.
Fish and marine organisms
Since oil floats, fish and other marine animals are not generally affected to the same extent as air-breathing vertebrates. However, if the spills are in shallow or confined waters, or if dispersal agents cause a lot of oil to reach the sea floor, huge damage can be caused to these species. Filter feeders, such as some shellfish and crustaceans, eat by removing any impurities – including oils – from the water, and as such, are unable to avoid exposure. This can cause either toxicity in certain species, which can be amplified through the food chain, or death if the exposure is great enough. In certain conditions, oil spills can also cause major fish kills, especially in protected lagoons or breeding areas⁴.
Not only do oil spills harm wildlife directly, they can also destroy or damage sensitive breeding grounds and other important habitats. While animals such as turtles may have no direct contact with the spill, they must come ashore at certain times of the year to breed. They can then be harmed by residual oils in the water or on the sand where they dig their nests. Alternatively, the oils could hit the beach after the mother turtle has laid her eggs and returned to the water, damaging the eggs and/or juvenile turtles².