Deepwater Horizon Oil Spill Linked To Dolphin Lung Damage And Hormonal Imbalances

Dolphins living in an area hit hard by the 2010 Deepwater Horizon oil spill are suffering from lung damage and hormonal levels that are lower than in any other recorded dolphin population, a new study has found.

The study’s findings are “consistent with petroleum hydrocarbon exposure and toxicity” and lend further insight to the NOAA-led Natural Resource Damage Assessment, an effort to find and quantify the environmental damage of the 2010 disaster. Researchers captured and ran tests on 29 bottlenose dolphins in Barataria Bay, Louisiana — an area that “received heavy and prolonged oiling” in 2010 as well as substantial dispersant exposure — and compared their findings to dolphins captured from Sarasota Bay, which was not affected by the oil spill.

Dolphins from Barataria Bay were 5 times more likely than Sarasota Bay dolphins to have moderate–severe lung disease, and nearly half of them had low levels of adrenal gland hormones. Nearly half of the dolphins tested were in “guarded” condition — meaning it wasn’t clear whether their health would improve or worsen — or worse, and 17 percent were in “poor or grave” health, meaning they were unlikely to survive.

“I’ve never seen such a high prevalence of very sick animals — and with unusual conditions such as adrenal hormone abnormalities,” Lori Schwacke, the lead author of the study, told the Times-Picayune.


The study’s link between the oil spill and the dolphins’ ill health adds to the Natural Resource Damage Assessment, which includes other studies on the environmental impact of the spill. If the studies find links between the oil spill and environmental damage, BP would be expected to pay for the damage — though for this particular study, BP is maintaining that the research doesn’t prove a link between oil exposure and dolphin health.

The study joins multiple others in linking the 2010 oil spill to serious health effects in dolphins and other marine life. A 2012 study found that a die-off of young dolphins off the Gulf Coast between January 1 and April 30 2011 was linked to oil exposure, which weakened the dolphins and made them unable to survive unusually cold ocean waters that spring. Following the disaster, fishermen in Barataria, Louisiana reported catching hundreds of pounds of eyeless shrimp, along with, according to one fisherperson in 2012, “eyeless crabs, crabs with their shells soft instead of hard, full grown crabs that are one-fifth their normal size, clawless crabs, and crabs with shells that don’t have their usual spikes … they look like they’ve been burned off by chemicals.” One study found Gulf killifish — an environmental indicator species — that were exposed to the sediments from sites affected by the oil had higher rates of developmental abnormalities compared to fish who weren’t, findings that are “predicative of population-level impacts in fish exposed to sediments from oiled locations along the Gulf of Mexico coast.”

And despite BP’s assurances that the company has made “significant progress cleaning the Gulf shoreline,” remnants of the spill continue to be discovered three years later. Cat Island in Barataria Bay, a former nesting ground for pelicans, has “eroded considerably” after the deaths of mangrove forests after the spill. In October, the Coast Guard unearthed a 4,100-pound tar mat off the coast of Louisiana, just four months after a 40,000-pound tar mat was discovered off the coast. And also in October, Tropical Storm Karen stirred up tar balls that washed ashore on a Louisiana barrier island.