The oil leak in the Gulf of Mexico is currently spewing out a ridiculous amount of crude oil. Original estimates suggested around 30,000 gallons per day though that has since risen to over 200,000 gallons and it is generally accepted that ascertaining the true volume escaping is nigh on impossible.
The leaks (there are three) began on the 22 April following explosions on, and the subsequent sinking of, BP’s Deepwater Horizon rig. Damningly, it has been revealed that only 12 months ago, a BP company exploration plan and environmental analysis concluded that a massive spill at this site was virtually impossible . Clean-up of the 10,000km2 slick is being hampered by difficult conditions and the delays inherent in implementing deep-sea solutions despite company assurances that while associated habitat would be affected by any spill, “due to the distance to shore [48 miles] and the response capabilities that would be implemented, no significant adverse impacts are expected” .
The ecological impact of this catastrophe will likely never truly be ascertained. While there are immediate signs – animals covered in oil, slicks on beaches and of course, the massive visible slick offshore – the collateral damage to the ecology of the region is likely to be extensive. Exposure to crude oil can have a detrimental effect on an organism even if there is no direct contact; the various volatile compounds can burn eyes, skin and sensitive membranes, damage red blood cells, liver, kidneys and spleen, and impair the immune response and reproductive system . Environmental conditions and differences in oil chemistry, including solubility, stability and stability, make specific effects difficult or impossible to predict.
|Probably the most publicly acknowledged casualties of oil spills are sea birds which inherently spend large amounts of time on, at or below the surface of the water foraging. While it might seem counter-intuitive to forage below an oil slick, especially as larger fish (and marine mammals) are able to, but do not necessarily, swim away from the area, studies have shown that some fish species can survive beneath floating oil [3, 4]. Oil is extremely damaging to feathers, ridding them of their waterproofing and buoyancy and the bird of its ability to fly. Add that to the damage caused by exposure to and/or ingestion of oil (poisoning, ulceration, etc.) and the deaths of seabirds in such circumstances are inevitable.
Some of the 400 species likely to be affected by the spill include :
- Brown pelicans
- Other shore birds such as sanderlings
- Loggerhead turtles
- Terrestrial mammals
- Blue crabs
- Myriad molluscs and fish
- Bottlenose dolphins
Such effects are evident in various taxa, though of course physiological differences mediate the type and extent of specific effects (e.g. feathers : skin : scales). Further damage is wrought on immature animals which may, for example, lack sufficient protective blubber to avoid chemical burns or whose feathers may not yet provide sufficient buoyancy or waterproofing to deal with limited contact. Plankton, which includes the larval stages of many marine species, are especially vulnerable to leached chemicals. Elimination of plankton from the food chain results in deprivation of dependent species such as shrimp, crabs, bivalves and immature fish. Indeed, the timing and location of the spill is especially unfortunate as it coincides with the breeding/spawning seasons of many species and will directly impact important breeding grounds and spawning sites.
It has been said that the spill in the Gulf of Mexico may prove to be the most damaging spill ever, even outstripping the massive environmental damage caused by the infamous Exxon Valdez disaster in 1989, the effects of which are lasting much longer than expected . Unfortunately, in thre present scenario, a fail-safe device failed, there seems to be no immediate fix and proposed ‘experimental’ solutions may take weeks or months to implement . While minor oil spills are relatively common (and isn’t that a worrying thought?), the environmental impact of this spill will be felt for decades and it is debateable whether local ecosystems will ever truly recover.
“Probably the only thing comparable to this is the Kuwait fires. The Exxon Valdez is going to pale in comparison to this as it goes on.” Mike Miller, head of Canadian oil well fire-fighting company Safety Boss. 
Edit – It would appear that BP are preparing to attempt to siphon the oil from the geyser into a surface barge. This will not happen for another week or so and may not actually work at all (though of course it’s worth a shot). 
 The Guardian – Gulf oil spill at Deepwater Horizon threatens $8bn clean-up and an ecological oil slick disaster for the US
 USA Today – First oil-soaked bird rescued off Louisiana
 Australian Maritime SafetY Authority – The effects of maritime oil spills on wildlife including non-avian marine life
 Kerley, G.I.H., Bowen, L. and Erasmus, T. (1987). Fish behaviour – a possible role in the oiling of seabirds. S. Afr. J. Wildl. Res. 17, 128-130.
 CNN – Oil spill could be disaster for animals, experts say
 Williamson, David (2003-12-18). Exxon Valdez oil spill effects lasting far longer than expected, scientists say. UNC/News (University of North Carolina at Chapel Hill). Retrieved 2008-03-09.
 BBC.co.uk – Gulf of Mexico slick said to be five times bigger
 Discover blogs: 80 beats – Gulf oil spill: Fisheries closed, Louisiana wetlands now in jeopardy