Time Will Tell

It’s been more than four years since the Deepwater Horizon oil spill and it seems that the Gulf’s pelagic fisheries have been largely unaffected. What are the possible future consequences and long term impacts? – Chad Murray


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Photo: Kris Krug/cc-by-SA 2.0

Even though the Gulf of Mexico may appear alive and well, the month-long BP oil spill discharged approximately 210 million gallons of crude oil, in addition to 1.84 million gallons of chemical dispersants. The Gulf’s oily surface covered thousands of miles of critically important spawning habitat for numerous species of pelagic game fish during peak spawning season. And we cannot forget the devastation of coastal wetlands from Texas to Florida.

To try and understand the long lasting impacts on the Gulf of Mexico’s most economically and ecologically important fisheries, a recent study brought together a team of experts from the UM Rosenstiel School of Marine and Atmospheric Science, Stanford University’s Hopkins Marine Lab, the University of the Sunshine Coast in Australia, and NOAA Northwest Fisheries Science Center.

The study replicated environmental exposures of two oil samples—one collected from surface skimming operations and another from the source pipe of the Deepwater Horizon wellhead—on embryos of bluefin tuna, yellowfin tuna and amberjack.

After assessing the impacts of polycyclic aromatic hydrocarbons (PAHs)—a toxic agent released from crude oil—it was determined that exposure to each oil type produced virtually identical defects in embryos of all three tested species. For each species, oil exposure caused serious defects in heart development, and abnormalities in heart rate and rhythm, indicating crude oil cardiotoxicity. For fast swimming pelagic species like tuna with incredible aerobic demands, the implications can be life threatening.

“This study is the first to understand the impacts of the Deepwater Horizon oil spill on the early life development of commercially important fish in the Gulf of Mexico,” said Daniel Benetti, director of the Aquaculture Program at UM and a coauthor of the study. “The findings can be applied to fisheries management questions in marine regions where crude oil extraction is prevalent.”

Unfortunately, bluefin tuna showed the highest percentage of larvae with the entire suite of defects, which is a serious concern since their populations are already listed by the IUCN as endangered due to historically low levels. Even worse, it is believed the Gulf of Mexico and Mediterranean Sea are the only bluefin spawning habitats in the entire world, so this could be very harmful to future breeding populations. Unfortunately, the damage is done and only time will tell the full impact of this unthinkable environmental disaster.

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