standard Ecological impacts of Deepwater Horizon oil spill

The long-term ecological impacts of the BP oil spill disaster may have recently come to light after scientists and fishermen have discovered fish and crustaceans with skin lesions or other abnormalities.  The US Food Drug Administration insists that seafood from the Gulf of Mexico is safe to eat regardless of what abnormalities have been found in species so far.  BP also maintains that seafood from the Gulf is as safe to eat as before the oil spill.  The US government led by Barack Obama is continuing to move forward with offshore drilling plans for oil and natural gas, including in the Arctic Ocean, bringing to question whether lessons have truly been learnt from the world’s largest oil spill disaster in history.

Around 206 million gallons (US) of oil was spilled from the Deepwater Horizon disaster.  By comparison Exxon Valdez spilled 11 million gallons (US) of crude.  What isn’t known entirely is the extent of the contamination from the oil blow out and the ‘clean up’ as the US government allowed BP to use 1.8 million gallons of dispersants on the surface of the spill and at the wellhead, something that has never been done before on this scale.  A study published in Environmental Science and Technology found one of the key ingredients of the dispersant known as ‘DOSS’ (dioctyl sodium sulfosuccinate) hundreds of miles from the wellhead where the disaster took place.  DOSS is known to be cancer causing and is mutagenic meaning that it can change the DNA of an organism, increasing the frequency of mutations.  Authors of the study found that DOSS had remained for 64 days at depths of 1,000-1,200 metres:

‘…DOSS was sequestered in deepwater hydrocarbon plumes at 1000−1200 m water depth and did not intermingle with surface dispersant applications. Further, its concentration distribution was consistent with conservative transport and dilution at depth and it persisted up to 300 km from the well, 64 days after deepwater dispersant applications ceased. We conclude that DOSS was selectively associated with the oil and gas phases in the deepwater plume, yet underwent negligible, or slow, rates of biodegradation in the affected waters. These results provide important constraints on accurate modeling of the deepwater plume and critical geochemical contexts for future toxicological studies’. (Fate of Dispersants Associated with the Deepwater Horizon Oil Spill, Environmental Science & Technology).

Another study focused on chemicals from the oil itself on Gulf killifish which are eaten by larger fish consumed by humans.  Multiple tissues taken from adult killifish found evidence of direct exposure to oil contaminants such as PAHs (poly-aromatic hydrocarbons) that are also carcinogenic and mutagenic.  They found that this persistent exposure to contaminants was consistent with the location and timing of the Deepwater Horizon event and were biologically available to developing fish.  A co-author of the study told AlJazeera:

‘That means that most of the large fish that we like to eat and that these are important fisheries for, actually feed on the killifish,” he explained. “So if there were to be a big impact on those animals, then there would probably be a cascading effect throughout the food web. I can’t think of a worse animal to knock out of the food chain than the killifish’. (‘Gulf seafood deformities alarm scientists’, AlJazeera)

This is the TV report from AlJazeera about the findings.  It is informative, but there is clear journalistic bias used here to push controversy.

The research may show that longer term effects on the Gulf food web remain to be seen.  Other research has compared shrimp abnormalities before and after the blow out.  Shrimp without eyes or eye sockets were found in the well area after the disaster, not before it.  Along the coast from west Louisiana to west Florida researchers found lesions, sores and infections on 20 species of fish that affected as many as 50 percent of the samples impacted, abnormalities found in fish before pre spill levels were 1/10 of one percent (see this transcription of broadcast from Democracy Now for further information).

The unfortunate situation many people in the Gulf fishing industry are in is that the only answer to how they will fare in the future is ‘wait and see’.  AlJazeera also spoke with a fisherman in the Gulf who said FDA officials refused to promise they would protect him from litigation if someone was made sick from eating his sea food, but what government agency could realistically do this?

As with many complicated environmental disasters, there are no easy answers and while BP has been fined for the disaster and there is more litigation on the way, the damage has been done.  If there are more risks present in the Gulf such as those involving health or even people’s livelihoods and well being they have to live with them.  A Gallup poll found depression diagnoses up 30 percent in Gulf-facing counties in the US.  People need new ways to mitigate the risks they currently face.  Perhaps this requires research initiatives that combine science with community or local knowledge in order to address problems that governments and private corporations simply cannot handle alone, as they are often blinded by the bureaucratic systems in place preventing any coherent understanding of what actual risks exist.

References and Further Reading

Gulf seafood deformities alarm scientists. AlJazeera

Fate of Dispersants Associated with the Deepwater Horizon Oil Spill. Environmental Science & Technology

Genomic and physiological footprint of the Deepwater Horizon oil spill on resident marsh fishes. PNAS


  1. Who do you trust? British authorities who claimed Cumbrian sheep were safe to eat after Chernobyl, Japanese authorities who claimed one could eat fish caught off shore of the crippled and leaking nuclear facility at Fukushima Dai Ichi, or US government experts who make similar claims? Why do such authorities think people are so ignorant and gullible?

  2. All very good questions. You are aware of this I’m sure, but for those who are not there has been very good work done on this highly important issue of trust by Brian Wynne on the Cumbrian sheep controversy on local vs scientific knowledge Could there be a parallel with Gulf seafood and Fukushima contamination? It seems so. We will likely see more work done on these sorts of problems in the future, but whether it will feedback into policy or better communication from governments to the public about risk is another matter.

  3. It’s also important to distinguish this controversy from historical examples because it is more complex in some cases. It simply isn’t about local vs scientific knowledge in this case, but knowledge of those who have more political power (federal government, BP) and those who do not namely university research scientists and fishermen. But maybe this is over simplifying?

    1. With power comes access to technology. For instance, images and water chemistry at very great depths, where BP was drilling, require sophisticated and expensive instrumentation. Local knowledge in this case requires only direct observation of the anatomy of the fish and crustaceans It’s interesting that local knowledge tends to be held in lower regard by ‘officials’.

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