Photo by the United States Coast Guard

Six Years After the Largest Oil Spill In US History

United States Coast Guard

It has been six years since largest oil spill in US history. On April 20, 2010, a fire broke out on the Deepwater Horizon drilling platform resulting in an explosion that killed eleven people and injured others. More than five million barrels of crude oil leaked from the wellhead before it was capped. The Deepwater Horizon oil spill is one of the most well-covered and well-documented oil spills in US history thanks to news and social media coverage, political and legal battles, and the restoration process that has been on going for the last six years.

Even six years later we are still learning and understanding the impact this oil spill has had on affected areas. In fact, scientists believe that the area affected was underestimated by almost 20 percent compared to previous estimates. A recent assessment conducted by private research companies found oil on 1,313 miles of coastline out of the 5,930 miles surveyed (Nixon, et al. 2016). The oil slick produced nearly 5 million barrels (about 60,000 barrels per day for the 87-day flow period) of oil lost by the Deepwater Horizon and spanned almost 30,000 square miles in the Gulf of Mexico. To date, 25 percent of the oil released is still unaccounted for.

Source: New York Times

New York Times

Six Years Later

It’s hard to believe that it has been six years since this environmental tragedy unfolded. Since then, legislation has been changed, some settlements have been paid, restoration efforts continue, and research is being conducted. In 2012 the RESTORE Act (Resources and Ecosystem Stability, Tourist Opportunities, and Revived Economies of the Gulf Coast States Act) was passed by the Obama Administration, in addition to the creation of the Gulf Coast and Ecosystem Restoration Council, which used money from penalties paid by BP and Transocean under the Clean Water Act. According to their 2015 report, they expected that BP would be required to pay $5.5 billion plus interest, and civic penalty. Transocean settled their lawsuit and paid one billion dollars plus interest. While additional lawsuits are still in progress, this month BP dropped the fight at the federal level and agreed to pay a $20.8 billion settlement to the Gulf States over a period of time (click here for a breakdown by state).

BP has estimated that the cost of the initial cleanup and various settlements (including criminal and civil penalties) will exceed $50 billion, the largest environmental penalty in history. The latest settlement includes the following allocation of funds:

  • $8.1 billion for damage to natural resources
  • $5.5 billion in Clean Water Act civil penalties
  • $350 million for state and federal assessment costs reimbursements
  • $250 million for response and removal costs reimbursements
  • $600 million is for other claims.
  • Up to $700 million for future unknowns.

Regulations regarding offshore drilling have also changed in the wake of this ecological disaster. Last year the government sought to increase the safety for both workers and the environment. This was the third time the government stepped into change policies and regulations since the disaster occurred in 2010. Additionally, oil spill response guidelines developed 25 years ago after the Exxon Valdez oil spill will likely be improved in the wake of Deepwater Horizon disaster. In fact, one improvement has already taken place. NOAA modified their guidelines for responding to oiled marine mammals so more animals can be helped in a shorter timespan with the hope that there will be reduction in fatalities associated with events like these (Ziccardi et al. 2014). While BP may have settled with the US government, it is clear that the days ahead will still be filled with other litigation and lawsuits. There are many pending private sector lawsuits and more may follow. This nightmare is far from over for BP and Transocean.

Photo by Charlie Riedel, AP

Charlie Riedel / AP

Research and Remediation

It is clear that restoration of the Gulf will be an ongoing effort for the foreseeable future. Food webs were greatly affected by the oil spill and continue to cause problems today. Oil deposits still affect all types of animal and plant populations. Both aquatic and terrestrial plants were affected by the oil spill and these can pose long term effects that will last for years. Coral reefs still show signs of damage (Mole, 2015). Meiofauna populations (small invertebrates such as marine worms and small arthropods) were impacted by the oil spill, which increased the nematode and small crustacean populations in some areas, but caused a decline in meiofauna populations in others (Baguley, et al. 2015). Some arthropod populations such as ants in oil-affected soil have smaller heads, indicating malnourishment, while other arthropods show no apparent population decline or other effects (Cornwall 2015).

There is also evidence that suggests that fish are undergoing genetic mutations as a result of exposure to oil toxins such as Polycyclic aromatic hydrocarbons (PAH). However, there seems to be little impact on some populations, such as killfish population, due to the number of offspring produced (Cornwall 2015). PAHs are derivatives from crude oil and can also disrupt cardiac function in fish lead to death. A study found that PAHs cause dose-dependent defects in Yellowfin tuna, Bluefin tuna, and Amberjack heart development (Incardona Et al. 2013). Other abnormalities and defects can be seen in various fish species as a result to oil exposure (Mole 2015). The fishing industry is likely forever changed by the events of the oil spill. The levels of toxicity and the number of mutations in fish may take years before they are diminished.

Additionally, there are still many areas of research to investigate as well as years of bioremediation that can hopefully lead to the recovery of the ecosystem. One poorly understood area is the assessment of immunotoxic effects. While they seem likely, these effects have not been investigated fully. They have huge implications in ecological heath including impaired disease resistance and increased opportunities for parasitism ultimately leading to a slower population recovery rate (Barron 2012).

Although the cameras stopped rolling, and media coverage ended, cleanup is far from over and the effects of the spill are not going to end anytime soon. Oil deposits are still found on Gulf coast beaches and more work is needed to restore habitats impacted by the oil. Hydrocarbons are found in a variety of animals and plants. To get an idea of how long it may take, one could compare this oil spill to the Exxon-Vladez that occurred over 25 years ago, which sparked the Oil Pollution Act in 1990. As of December 2009, Exxon paid all of its punitive damages totaling roughly $508 million. Most importantly, the ecosystem is rebooting after the collapse of the marine population and some populations are finally hitting pre-spill numbers. Scientists have been monitoring the area around Prince William Sound, Alaska where the spill occurred. Even over 25 years later, it is estimated that there are still 16,000-21,000 gallons of oil still on the beaches and oil can even be found up to 550 miles away (Ahern 2014).

Photo by Carolyn Cole / Los Angeles Times

Carolyn Cole / Los Angeles Times

Highlight of Ecological Losses in Last Year’s National Wildlife Federation Report

  • Approximately 8.3 billion oysters were lost.
  • 2-5 trillion larval fish in the Gulf were lost.
  • Approximately 20 percent of female adult Kemp’s Ridley sea turtles were estimated to be lost.
  • 32 percent of laughing gulls were lost.
  • 12 percent of brown Pelicans were lost
  • The National Academy of Sciences found the use of chemical dispersants did not accelerate biodegradation of oil, and may have suppressed it.
  • Oil and dispersant compounds have been found in the eggs of white pelicans nesting in Minnesota, Iowa, and Illinois.
  • 770 square miles of sea floor near the wellhead have been damaged and oil can be found in deep sediment in a 1,200 square mile radius around the wellhead.
  • Coral colonies still show significant oil damage.
  • Sperm whales spend less time foraging around the wellhead.
  • Spotted seatrout spawn less frequently than in pervious years.
  • Abnormal development has occurred in many species of fish as a result of oil exposure.

Click here for the full report, titled, Five Years & Counting – Gulf Wildlife in the Aftermath of The Deepwater Horizon Disaster.

Photo by NOAA


Impacts of the Deepwater Horizon Oil Spill on Marine Mammals

Over 25,000 marine mammals are estimated to be have been effected by the oil spill. There have been over 150 marine mammal deaths associated with the oil spill and 90 percent of these deaths are Atlantic bottlenose dolphins. Venn-Watson and others (2015) found that oil spill-associated bottlenose dolphins fatalities are likely linked to pneumonia and the development of growing lungs. This is discovered upon post-mortem ultrasounds and necropsies. The actual number of cetaceans that have died is likely an underestimation of the animals affected by the oil spill because the number is extrapolated from the number of dead animals that have been found (Williams, et al. 2011). Most cetacean necropsies associated with oil spill-related deaths revealed that the cause of death as chronic adrenal insufficiency resulting from adrenal gland lesions.  This is especially true when challenged with pregnancy, cold temperatures, and infections leading to life-threatening situations or an increased susceptibility to pneumonia, due to lung lesions, or alterations in immune function.

Additionally, there have been over 400 stranding events that are related to the oil spill. Research has shown that bottlenose dolphin populations in Florida are healthier than populations found in the northern Gulf of Mexico. In another case study, bottlenose dolphins in Barataria Bay, Louisiana had a significantly greater prevalence for lung disease and severity compared to those in Sarasota Bay dolphins, as well as those previously reported in other wild dolphin populations. Barataria Bay dolphins were five times more likely to contract moderate–severe lung disease, (characterized by significant alveolar interstitial syndrome, lung masses, and pulmonary consolidation), an uncommon disease that is consistent with petroleum hydrocarbon exposure and toxicity. Many of the dolphins were given a guarded or worse prognosis, and some were even considered in poor or grave condition indicating that they were not expected to survive (Schwacke et al. 2014). It is clear that the Gulf of Mexico populations have suppressed immune function making the dolphins more susceptible to infections, such as pneumonia and morbilivirus, when compared to wild dolphin populations of Florida (Venn-Watson et al. 2015).

Photo by the Louisiana Department of Wildlife and Fisheries

The Louisiana Department of Wildlife and Fisheries

After six years, we’re only scratching the surface of the damage caused by the Deepwater Horizon oil spill. We will continue to learn the ecological impact as more research is conducted. We may find that the impacts of the oil spill extend farther than the Gulf of Mexico. In fact, one study suggests that sea turtle populations found in other parts of the world such as the Atlantic coast of the US and in West African countries are seeing turtles that were affected by the oil spill (Pullman et al. 2015). This leads to a very different research question. Given that many of the animals affected are transient animals, what is the true global impact of the Deepwater Horizon oil spill? That is a question that will take years to investigate, but one thing is certain; a local spill can have huge impacts on the ecology of not just the affected area, but migration routes may carry hydrocarbon residues that could threaten other wildlife not associated with the oil spill.


Literature Cited

Ahern A. 2014. 25 years later, scientists still spot traces of oil from Exxon Valdez Spill.

Baguley J, Montagna P, Cooksey C, hyland J, Bang H, Morrison C, Kamikawa A, and Bennetts P. 2015. Community response of deep-sea soft-sediment metazoan meiofauna to the Deepwater horizon spill blowout and oil spill. Mar Ecol Prog Ser. 528: 127-140.

Barron MG. 2012. Ecological impacts of the Deepwater Horizon oil spill: implications for immunotoxicity. Toxicologic pathology, 40(2): 315-320.

Carmichael RH, Graham WM, Aven A, Worthy G, & Howden S. 2012. Were multiple stressors a ‘perfect storm’for northern Gulf of Mexico bottlenose dolphins (Tursiops truncatus) in 2011?. PLoS One, 7(7): e41155.

Cornwall W. 2015. After the oil: Five years on, the worlds largest accidental marine spill has left subtle scars on the Gulf of Mexico. Science, 348 (6230) 22-29.

Incardona J, Gardner L, Linbo T, Brown T, Esbaugh A, Magerc E, Stieglitzc J, Frencha B, Labeniaa J, Laetza C, Tagala M, Elizurd A, Benettic D, Grosellc M, Blockb B, and Scholza N. 2014. Deepwater hoizon crude oil impacts the developing hearts of large predatory pelagic fish. PNAS 111 (15): E1510–E1518, doi: 10.1073/pnas.1320950111

Martin C. 2012. Gulf Spill two years out. Current Biology 22 (10) pR384-R386.

Nixon Z, Zengel S, Baker M, Steinhoff M, Fricano G, Rouhani S. and Michel J. 2016. Shoreline oiling from the Deepwater Horizon oil spill. Marine Pollution Bulletin.

Putman NF, Abreu-Grobois FA, Iturbe-Darkistade I, Putman EM, Richards PM, and Verley P. (2015). Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic. Biology letters, 11(12): 20150596.

Schwacke LH, Smith CR, Townsend FI, Wells RS, Hart LB, Balmer BC, Collier TK, De Guise S, Fry MM, Gullette LJ Jr, Lamb SV, Lane SM, McFee WE, Place NJ, Tumlin MC, Ylitalo GM, Zolman ES, and Rowles TK. 2013. Health of common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana, following the Deepwater Horizon oil spill. Environmental science & technology, 48(1), 93-103.

Venn-Watson S, Colegrove K, Litz J, Kinsel M, Terio K, Saliki J, Fire S, Carmichael R, Chevis C, Hatchett W, Pitchford J, Tumnlin M, Field C, Smith S, Rotstein D, McFee W, Fougeres E, and Rowles T. 2015. Adrenal gland and lung lesions in Gulf of Mexico common bottlenose dolphins (Tursiops truncatus) found dead following the Deep water Horizon oil spill. PLOS ONE DOI:10.1371/journal.pone.0126538 1-23.

Williams R, Geri S, Bejder L, Calambokidis J, Kraus S, Lusseau D, Read A, and Robbins J. 2011. Underestimating the damage: interpreting cetacean carcass recoveries in the context of the Deepwater horizon/BP incident. Conservation Letters. $: 228-233.

Ziccardi M, Wilkin S, and Rowles T. 2014. Modification of NOAA’s National Guidelines for Oiled Marine Mammal Response as a Consequence of the Macondo/Deepwater Horizon Oil Spill. IOSC Proceedings. doi/pdf/10.7901/2169-3358-2014.1.986.

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