Oil spills such as the 58,000 gallon discharge after a freighter hit the San Francisco-Oakland Bay Bridge a few days ago have a terrible and long lasting effect on waterways and coastlines.
When oil is spilled in waterways, it spreads very quickly with the help of wind and currents. It took only hours for the SF spill to spread 40 miles.
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 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. This 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.
The recent SF incident was considered a "medium" sized spill. There's nothing "medium" about a 40 mile oil slick in my opinion, but there have been many far worse incidents; here's four of the biggest marine spills in history.
Persian Gulf - January 23, 1991 - up to 1,500,000 tonnes
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 14 known marine oil spills consisting of over 100,000 tonnes. One tonne of crude oil is roughly equal to 308 US gallons.
It's interesting to note that the Exxon Valdez disaster isn't among the "100,000" club - but it was the largest spill in U.S. history and given where it occurred, one of the biggest ecological disasters. Among its toll, the spill killed hundreds of thousands of sea birds, thousands of otters, hundreds of seals as well as killer whales, bald eagles and fish.
On a side note, while the Exxon Valdez incident occurred on March 24, 1989; the company is still refusing to pay the $2.5 billion punitive damages it was ordered to. Exxon Mobil Corporation is the parent of Esso, Mobil and ExxonMobil companies; you can show your disgust by getting your gas elsewhere - nothing speaks louder than consumer dollars.
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