Deepwater Horizon’s Impact on Wildlife

Since the Deepwater Horizon explosion in April of 2010, the National Wildlife Federation and its Gulf of Mexico Restoration program have closely monitored the scientific research on the impacts of the disaster on wildlife and the ecosystems of the Gulf of Mexico. 

In late 2015, the federal government released an in-depth official report, known as the Programmatic Damage Assessment and Restoration Plan. This comprehensive study makes it clear that wildlife and habitats throughout northern Gulf were damaged by the oil and dispersants, and for many species the impacts are ongoing. The report concluded, “These injuries affected such a broad array of linked resources and ecological services over such a large area that they can best be described as an injury to the entire ecosystem of the northern Gulf of Mexico.” 
 
Here are some of the findings from the federal report and additional peer-reviewed research into the impacts of the disaster:

Dolphins and Whales

• Nearly all of the 21 species of dolphins and whales that live in the northern Gulf have demonstrable, quantifiable injuries
• The number of bottlenose dolphins in Barataria Bay and the Mississippi Sound—two places particularly affected by oil—are projected to decline by half. Multiple studies have determined that the injuries to bottlenose dolphins were caused by oil from the disaster.
• It is estimated that it will take approximately one hundred years for the spinner dolphin population to recover.
• There are only a few dozen Bryde's whales in the Gulf. Nearly half this population was exposed to oil, and nearly a quarter of these whales were likely killed. The long-term survival of this population is in doubt.

Sea Turtles

• Scientists estimate that as many as 167,000 sea turtles of all ages were killed during the disaster.
• In 2010, the once-remarkable recovery of the endangered Kemp's Ridley sea turtle halted abruptly. Scientists remain concerned about this species of sea turtle, which is known to congregate and feed in areas that were oiled off the Louisiana coast.
• Heavy oil affected nearly a quarter of the Sargassum—a type of floating seaweed—in the northern Gulf. Sargassum is an important habitat for juvenile sea turtles.

Fish

• Studies have determined that oil is particularly toxic for many species of larval fish, causing deformation and death. The federal study estimates that the disaster directly killed between two and five million larval fish.
• The data does not indicate that the oil spill caused significant decreases in populations of commercially harvested fish species.
• However, a number of species of fish have documented oil spill injuries. For example in 2011, some red snapper and other fish caught in oiled areas had unusual lesions, rotting fins, or oil in their livers. Oil spill impacts have been documented in fish species such as southern flounder, redfish, and killifish.

Birds

• At least 93 species of bird were exposed to oil. The resulting loss of birds is expected to have meaningful effects on food webs of the northern Gulf of Mexico.
• Species particularly affected include brown and white pelicans, laughing gulls, Audubon's shearwaters, northern gannets, clapper rails, black skimmers, white ibis, double-crested cormorants, common loons, and several species of tern.
• A 2017 study found that birds with even relatively small amounts of oil present sustained damage to their red blood cells and had evidence of anemia, which can adversely affect reproduction and survival.

The Gulf Floor

• A significant portion of the Gulf floor was affected by oil. The federal study confirmed that at least 770 square miles around the wellhead were affected, while a separate analysis determined that at least 1,200 square miles were affected. Both studies suggested that a significant amount of oil was likely deposited on the ocean floor outside the areas of known damage.
• Scientists estimate the habitats on the bottom of the Gulf could take anywhere from multiple decades to hundreds of years to fully recover.
• Coral colonies in five separate locations in the Gulf—three in deep sea and two in shallower waters—show signs of oil damage.

Coastal Habitats

• In Louisiana, erosion rates approximately doubled along roughly 100 miles of shoreline. The effect lasted for at least three years. Louisiana already had one of the highest rates of wetlands erosion, even before the disaster.
• Oil and response efforts killed as many as 8.3 billion oysters. These losses have put the sustainability of oysters in the Gulf of Mexico at risk.