The BP oil spill saga continues..

By: Dana Sackett

More than 2 years have passed since the BP–Deepwater Horizon rig spill caused more than 200 million gallons of oil and 1.8 million gallons of dispersants to be dumped into the Gulf of Mexico. Despite being one of the largest oil spills in history, the Gulf fisheries were back in business only months after the flow of oil was plugged.  The decision to re-open the fisheries was based on promising initial reports that the chemicals from the spill would degrade relatively quickly and result in minimal damage to the environment. However, recent research suggests that the ecological impacts may be more widespread than originally thought.

The Deepwater Horizon rig on fire in April 2010. Source:

While an oil spill is damaging to an ecosystem, oil is actually made-up of thousands of compounds and not all compounds are equal.  Following the Exxon Valdez spill in 1989, researchers discovered that the majority of toxic chemicals in oil are a family of compounds called polycyclic aromatic hydrocarbons (PAHs). These compounds contain benzene rings fused together by carbon bonds. PAHs are often left behind after the bulk of the oil is cleaned up.


A few different PAHs. Historically, PAHs with more rings are considered more carcinogenic. Source:

In the lab, PAHs found in oil have recently been linked to heart failure and developmental deformities in fish embryos. Brief exposure to very low concentrations of oil kills embryos and hatchlings of a number of different fish species (from large open-ocean tuna and mahi to small coastal species). Most of those exposed to oil that survived, had major deformities that diminished their ability to survive in the natural environment.

Killifish embryos exposed in the lab to sediment retrieved from oil-tainted coastal regions developed with some major deformities (top panel), including a malformed, elongated heart (arrow) and edema (star). Exposure to untainted sediments resulted in normal development of the heart cavity (bottom). Credit: Benjamin Dubansky/LSU

In the Gulf, open sores, parasitic infections, chewed-up-looking fins, gashes, mysterious black streaks and lesions have been reported on recently collected fish. With the lack of baseline data on sick fish in the Gulf before the spill and the other contaminants that often flow into the Gulf of Mexico, it is difficult to directly link these adverse effects to the BP oil spill, but the circumstantial evidence is compelling.

Sores and strange black streaks are more commonly seen in fish near the site of the BP oil spill. Source:

For instance, scientists caught 4000 fish during several cruises last summer from Florida to Louisiana and found the incidence of gashes, ulcers, fin rot, large open sores and parasites grew more prevalent as they neared the site of the spill. Scientists have also noted reduced diversity, fewer seaweed, crabs, lobsters and other aquatic life, as well as crustaceans with lesions, lost appendages and black gunk on their gills near the site of the spill. The demise of a community of deep-sea coral was also recently linked to oil that was chemically fingerprinted as having come from the BP spill.


Many scientists, fishermen and ecologists blame chemicals from BP’s oil and dispersants for a growing number of seafood deformities and mutations, such as these eyeless shrimp, caught in Louisiana’s Barataria Bay in September 2011. Source: 

Human health concerns from consuming contaminated seafood has recently been a hot topic as well. Following the spill, the FDA calculated allowable thresholds, known as levels of concern (LOCs), for PAHs in different types of Gulf seafood. When seafood was measured below these LOCs the Gulf fisheries were reopened (summer and fall of 2010). However, the decision to resume commercial fishing hinged on the accuracy of the FDA assumptions in calculating the LOCs, and these assumptions have recently come under fire. For instance, many of these assumptions were inconsistent with the FDA’s own prior practice and with risk assessment guidelines produced by other national and world agencies (NRC, WHO, USEPA).

Oil from the BP oil spill in the surf off Alabama. Source:

Some of the inconsistencies in the FDA assumptions include: using an estimated body weight of176 pounds, which under-protects nearly 75 percent of women and children; not properly accounting for consumption of seafood by pregnant women; and assuming a 5 year exposure to contaminated Gulf fish when research from the 1989 Exxon Valdez oil spill indicated that PAHs were still detectable up to 13 years later.  Additionally, independent researchers calculated LOCs for two carcinogenic PAHs in oil much lower than the level set by the FDA. Researchers have, therefore, suggested the FDA reevaluate the LOCs set for PAHs in Gulf seafood.

New oil slicks were recently spotted in the Gulf. The source of the oil causing these new oil slicks are unknown. Source:

The saga of the BP oil spill continues today.  New oil slicks have recently been spotted in the Gulf suggesting to some that this oil spill may not be over yet.  In addition to the new oil leaking into the Gulf, an “unidentified substance inconsistent with oil” was seen emitting from several areas of the BP’s Deepwater Horizon wreckage.  In November BP pled guilty to more than a dozen felonies from the 2010 disaster, including lying to Congress about how much oil was really pouring into the Gulf.  BP is now required to pay an additional 4.5 billion dollars in fines and restitution as a result of this plea.

Understanding the effects of these oil spills are not only important to help damaged ecosystems recover but also to help the people that depend on the fishery for their livelihood and sustenance.  The enormous amount of research being funded to better understand this disaster will hopefully help us become better prepared to deal with and even prevent another disaster in the future.


References and more information:

Bjorndal KA, Bowen BW, Chaloupka M, Crowder LB, Heppell SS, Jones CM, Lutcavage ME, Policansky D, Solow AR, Witherington BE. 2011. Better science needed for restoration in the Gulf of Mexico. Science 331: 537-538

Hjermann DO, Melsom A, Dingor GE, Durant JM, Eikeset AM, Roed LP, Ottersen G, Storvik G, Stenseth NC. 2007. Fish and oil in the Lofoten-Barents Sea system: synoptic review of the effect of oil spills on fish populations. Marine Ecology Progress Series 339: 283-299

Incardona JP, Collier TK, Scholz N. 2011. Oil spills and fish health: exposing the heart of the matter. Journal of Exposure Science and Environmental Epidemiology

McCall BD, Pennings SC. 2012. Disturbance and recovery of salt marsh arthropod communities following BP Deepwater HOrizon oil spill. PloS ONE 7: 1-7

Rotkin-Ellman M, Wong KK, Solomon GM. 2012. Seafood contamination after the BP Gulf oil spill and risks to vulnerable populations: a critique of the FDA risk assessment. Environmental Health Perspectives 120: 157-161

Silliman BR, Koppel Jvd, McCoy MW, Dillar J, Kasozi GN, Earl K, Adams PN, Zimmerman AR. 2011. Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill. PNAS 109: 11234-11239

Slick Science: Will New BP Funds Keep Gulf Genomics Afloat. Cell 146, 2011

Tucker C. 2012. FDA may underestimate danger of BP oil spill to seafood consumers. American Public Health Association Jan., 2012, Pg 12

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