As we all know, oceans cover more than three quarters of the earth’s surface. It is considered the largest habitat on earth. Oceans provide a large proportion of oxygen we breathe. It also provides 15% of the animal protein we consume. Hence, even small oil spills can result in large-scale effects. One example will be the case on San Cristobal Island. More than 60% of the marine iguanas on Santa Fe Island in the Galapagos were killed within months of a relatively small oil spill in 2001 when a leaking tanker encircled San Cristobal Island.

The biggest spill occurred during the 1991 Persian Gulf War when about 240 million gallons spilled from oil terminals and tankers off the coast of Saudi Arabia. The second biggest occurred over a ten-month period (June 1979 – February 1980) when 140 million gallons spilled at the Ixtoc I well blowout in the Gulf of Mexico near Ciudad del Carmen, Mexico.

As we can see, the effects of oil on marine life are caused by either the physical nature of the oil (physical contamination and smothering) or by its chemical components (toxic effects and accumulation leading to tainting). Marine life may also be affected by clean-up operations or indirectly through physical damage to the habitats in which plants and animals live.

Similarly, oil, tar balls, dead fish and birds all get washed up on the shores and the oil slick interferes in activities such as fishing, sailing, swimming, etc The local tourist industry suffers as well because tourists are not interested in visiting a coastal area where they cannot do the activities listed above. Furthermore, industries that rely on clean seawater for routine operations can also suffer because operations have to be stopped while the water is cleaned.

One may say it would be possible to reduce the severity of oil spills if humans are less dependent on oil. Indeed, the occurrence of oil spills will be greatly reduced if less oil is being transported. However, oil still remains the most fundamental resource today. It will be costly to replace oil with other alternative resources such as nuclear power or hydro-electrical power. Therefore, as long as oil remains the main resource powering the world’s industries, we must find an effective long term solution to oil spills.

Causes

One common cause is accidents. There is often a large loss of oil in accidents. The following are the statistics on the number of times it happened between 1974 and 1999. 475 oil spill cases resulted from collisions while hull failures occurred 671 times. On the other hand, fires and explosions were the most uncommon type. There were only 154 cases. Groundings happened 518 times and the greatest amount of oil lost in a single spill is over 700 tonnes.

Oil spills also occur due to regular operation. Most of the oil spillage is caused when ships are carrying out routine operations at ports or oil terminals. However, the majority of these spills are small. 93% of them produced a spillage of less than 7 tonnes. Oil spillage due to loading and discharging took place 3070 times. Bunkering is the least common operational cause. There were only 566 of such cases.

Another cause is leakage from old, damaged or badly maintained storage tank. This, partnered with oil leakage from the oil platforms can contribute to mass oil spillage. For example the Alaska pipeline which pumps oil continuously often experiences leakages that can spill up to a tonne of crude oil into the sea before the pipe can be dug up and replaced.

Furthermore, natural seepage from underground leaks out and floats up unto the sea surface, thus causing patches of oil pollution on the sea’s surface.

Impact

Oil spills can have a serious economic impact on coastal activities and people who obtain their resources from the sea. The impact on marine life is compounded by toxicity and tainting effects resulting from the chemical composition of oil and the diversity and variability of biological systems and their sensitivity to oil pollution.

People who gain their livelihood from the tourism industry can also be affected greatly. The onshore infrastructure associated with offshore oil can cause significant harm to the coastal zone. Some industries are at the existing economic base of the affected coastal communities. Many of them rely on tourism, coastal recreation and commercial and recreational fishing. A contamination of coastal amenity areas can occur. This can lead to public disquiet and interference with recreational activities for instance bathing, boating and diving. Some industries that rely on clean supply on seawater are also adversely affected by the oil spillage.

Fish may be exposed to spilled oil by direct contact. In this case, their gills might get contaminated or their eggs might absorb some components of oil. They may also eat contaminated food without knowing it. Hence, they may suffer changes in their heart and respiratory rate. Some may even have enlarged livers, reduced growth, fin erosion, a variety of biochemical and cellular changes, and reproductive and behavioral responses. Furthermore, chronic exposure to certain chemicals found in the oil may cause genetic abnormalities or cancer in some species. This in turn will affect humans.

On the other hand, the main threat posed to other aquatic organisms by the persistent residues of spilled oil and water-in-oil emulsions (”mousse”) is one of physical smothering. The animals and plants most at risk are those that could come into contact with a contaminated sea surface. Marine mammals and reptiles, birds that feed by diving or form flocks on the sea, marine life on shorelines, and animals and plants in mariculture facilities are among the few that could be affected.

Birds, such as seabirds, spend a lot of time on the ocean’s surface. They dive into the ocean when they are disturbed. Moreover, they have low reproductive rates, making them particularly vulnerable to oil spills. A bird’s feathers overlap to trap air and provide the bird with warm and buoyancy. If the bird gets oil on its feathers, they may ingest the oil while trying to clean their feathers. They may also eat contaminated food, suffering long-term reproductive effects.

Mammals can also be affected. Some examples of mammals are river otters, polar bears and land mammals. The amount of damage is the most directly related to how important the fur and the blubber are to stay warm. The animals listed as examples above require clean fur to remain warm. Direct exposure to oil can result in temporary eye problems while ingestion of oil can result in digestive tract bleeding as well as liver and kidney damage. This is of greater concern for species that groom themselves with their mouth, such as the polar bear.

Conclusion

Clearly, oil spills are a threat humans, animals and the surrouding environment. The entire ecosystem suffers after every spill, each and every one caused by our inability to recognize the dangers of oil spills. It seems that only devastating oil spills will force us into action, as did the Exxon-Valdez spill in prompting double-layer tanker walls. Must we wait for another more devastating spill before we ensure that the most sophisticated of oil spill prevention and clean up technology is utilized, despite the cost?

oil spills, environment, clean up, technology