Deepwater Horizon: The Worst Oil Spill in History

Part 1 of a 3 part series on the Deepwater Horizon oil spill by Joana Tavares-Reager, oceanographer and marine policy expert.  As with all things we classify as disasters, it is sometimes hard to find the silver lining.  The aim of the series is to discuss the broader impacts of the spill and make an important connection to each of our daily lives.

The Earth continues to bleed oil into the Gulf of Mexico, as we sit in dismay in front of our TV sets.

87 days have gone by since the Deepwater Horizon, the ultra-deepwater offshore drilling rig that sunk into the waters over the Macondo Prospect some 41 miles off the Louisiana coast, causing crude oil to leak from the pipe that connects the well at the ocean floor to the drilling platform on the surface. The images are shocking, the official numbers are unreliable and the long-term impacts on marine life still inestimable.

The Deepwater Horizon has escalated into the largest oil spill in the history of mankind

Official flow rate calculation initially estimated the amount of oil leaking into the Gulf waters to be between 5,000 and 19,000 barrels of oil per day.  These estimates have been updated in mid-July to 35,000 to 65,000 barrels per day which would amount to a total between 3 and 5,5 million barrels of oil poured into the ocean since the spill began, about twelve weeks ago.

These numbers place the Deepwater Horizon spill as the worst oceanic oil spill in history, above the estimated 4-6 million barrels of oil dumped into the Arabian Gulf by Iraqi forces in order to frustrate a potential landing by US Marines, in what then became known as the Gulf War oil spill in early 1991.

AP Photo

Spills simply keep on killing

A recent study published in the scientific journal Environmental Pollution by researchers from Research Planning Inc., summarized the environmental impacts of the Gulf War oil spill and showed that twelve years after the incident, sediments from coastal habitats particularly along the southern portion of the shoreline of Saudi Arabia still contains high concentrations of toxic compounds, specifically polycyclic aromatic hydrocarbons, which can be extremely harmful to organims that inhabit the seafloor.

Long-term consequences of oil spills have been observed in other impacted regions as well, such as in Prince William Sound, Alaska, where the oil tanker Exxon Valdez spilled 257,000 barrels of oil in 1989.  In a 2003 paper published in the journal Science, researchers from several institutions, including the National Marine Fisheries Service, NOAA, USGS and FWS have shown that persistence of toxic oil accumulated underwater and continued exposures, even at sublethal levels, have been affecting wildlife since the accident took place. The recovery of the local ecosystem has been delayed by major reductions in populations and cascading indirect effects of toxic oil compounds. Their findings were very relevant because they challenged the way ecological risks of oil in the oceans are assessed.

Previously, it was assumed that impacts to populations derive almost exclusively from mortality that occurs immediately upon the oil spill, but the measurements taken by these authors 14 years after the spill, denounced the need for ecosystem-based toxicology that understands and ultimately predicts chronic, delayed, and indirect long-term risks and impacts. This study also showed that certain clean-up attempts can be more damaging to coastal communities than the oil itself, with impacts recurring as long as clean-up (including both chemical and physical methods) continues. Because of the pervasiveness of strong biological interactions in rocky intertidal and kelp forest communities, cascades of delayed, indirect impacts (especially of trophic cascades and biogenic habitat loss) expand the scope of injury well beyond the initial direct losses and thereby also delay recoveries.

Unfortunately, the damages caused by the Deepwater Horizon in the Gulf Mexico will be long-lasting as well.  Populations of fish, crustaceans, molluscs, marine mammals, birds, turtles as well as microorganisms that compose the basis of the food web are being severely impacted and the effects of oil contamination will persist through several generations. Long-term exposure of fish embryos to oil, for instance, may affect growth, cause deformities, and modify behavior with long-term consequences on mortality and reproduction.

Please join us for Part 2 of the 3 part series on the Deepwater Horizon oil spill next week, which will discuss the use of chemical dispersants and their impact.

One Response to “Deepwater Horizon: The Worst Oil Spill in History”

1. Breakfast Nook says:

   December 2, 2010 at 9:32 am

   oil spills can really mess up the environment, i hope we can find a very good solution to control oil spills ,~`

   Reply