Effects of oil spills

Originally published November 2007, last updated August 2010

Oil slicks do so much more damage than just the initial havoc we see on the news – the effects can be very long lasting.

Since first publishing this article in 2007 and even though oil has become even more precious in a world now coming to terms with the fact peak oil is a reality rather than possibility, we’ve continued to see significant oil leaks and spills occurring on a fairly regular basis.

The recent Deepwater Horizon BP oil leak disaster in the Gulf of Mexico well and truly eclipsed the Exxon Valdez oil spill of 1989 and now has the dubious distinction of being one of the largest oil spills on record. Latest official estimates (August 2, 2010) state approximately 4.1 million barrels of oil contaminated the ocean.

Effects of oil spills

When oil is spilled or leaked into in waterways and the ocean, it spreads very quickly with the help of wind and currents. A single gallon of oil can create an oil slick up to a couple of acres in size! The BP oil slick had spread over 580 square miles in just three days.

When oil starts mixing in water, it can change composition and becomes what’s known as “mousse”. This is a sticky substance that clings even more to whatever it comes in contact with. Many marine animals don’t know to avoid a slick and some fish may even be attracted to it as it can resemble food.

Some of the many effects on animals coming into contact with crude oil include:

– hypothermia and drowning of birds as the oil breaks down the insulating capabilities of feathers, makes them heavier and compromises flying ability

– hypothermia in some seal pups as the oil destroys insulating fur

– if oil is ingested, it can either poison the animal outright, make them extremely sick or create a level of toxins in their system that then causes poisoning further up the food chain. Birds and other animals often ingest oil when trying to clean themselves. Shellfish and corals are particularly at risk in these scenarios as they cannot escape from an oil slick.

– damage to the airways of birds and animals.

– damage to animal immune systems

– interruption of breeding and fouling of breeding grounds

– thinner bird and turtle egg shells and also damage to fish larvae, causing deformities

– damage to sea grass beds and other shelter/feeding areas

– tainting of algae, which perform a vital role in waterway ecosystems

Even once the oil appears to have dissipated, it can still lurk beneath the surface of beaches and the sea bed, severely affecting marine organisms that burrow, such as crabs, for literally decades. These burrowing creatures are also food for other animals, so the cycle of poisoning continues for many years.

There’s really no aspect of a marine and coastal environment that is not in some way adversely affected by an oil spill. The closer the spill occurs to the shoreline, the more pronounced the damage will be due to coastal zones being home to more concentrated and diverse populations of marine, bird and animal life than far out to sea.

World’s biggest oil spills.

Here’s five of the biggest marine spills in history.

Persian Gulf – January 23, 1991 – up to 1,500,000 tonnes
Gulf of Mexico – 2010 – approximately 574, 000 tonnes (August estimate)
Gulf of Mexico – June 3, 1979 – 454,000 – 480,000 tonnes
Trinidad and Tobago – July 19, 1979 – 287,000 tonnes
Fergana Valley Uzbekistan – March 2, 1992 – 285,000 tonnes

There have been a total of 15 known marine oil spills consisting of over 100,000 tonnes. One tonne of crude oil is roughly equal to 308 US gallons; so in the Persian Gulf incident, approximately 462 million barrels were spilled – 20 times more than the USA consumes in a day, over a year’s worth of consumption for Australia and enough to supply the entire world’s crude oil needs for around 5 days.

It’s interesting to note that the Exxon Valdez disaster, isn’t among the “100,000” club – it wasn’t even close at approximately 35,000 tonnes – but previous to the 2010 Gulf of Mexico disaster, it was the largest spill in U.S. history and given where it occurred, one of the biggest ecological disasters the nation has experienced. That spill killed hundreds of thousands of sea birds, thousands of otters, hundreds of seals as well as killer whales, bald eagles and fish. It’s not just how much oil is spilled that plays a role in the devastation that occurs, but where it is spilled.

Oil leaks and spills don’t just affect marine life – they have a direct impact on humans too long after the initial media frenzy has died down. Some Alaskan communities were affected by the Exxon Valdez disaster as important commercial fishing and hunting grounds were contaminated for an extended period. Tourism was also affected.

Unfortunately the people, creatures and ecosystems of Louisiana and other states are now experiencing the same..


Caring for our waterways