Major impacts on dolphins from Deepwater Horizon oil spill
It’s been several years since the Deepwater Horizon oil rig exploded in the Gulf of Mexico, leading to one of the largest oil spills in recorded history. That means we’re now getting good scientific studies of how the ecosystems in the gulf reacted to and recovered from the disaster.
A study has just been published in the journal Environmental Science and Technology looking at the health of dolphins in the Gulf after the spill and their results are disconcerting.
A team led by NOAA scientist Lori Schwacke visited Batavia Bay off the coast of Louisiana in 2011, over a year after the start of the oil spill, and investigated the health of local dolphins. Their results weren’t positive, to say the least.
Of that group, 48% were unhealthy. In the group exposed to the oil, they found a variety of issues, including hypoadrenocorticism (consistent with adrenal exposure to toxic chemicals), lung issues at 5 times the rate of the normal population, and large numbers that were underweight. Many of the dolphins with breathing issues also had growths on or within their lungs.
Of this group, they estimated that just under 20% would be unlikely to survive, and 30% were marginal cases.
By comparing this population to dolphins in Florida, unaffected by the spill, the scientists make a strong case that the problems in the Batavia Bay dolphins are directly related to the spill. Populations in the area not exposed to the oil don’t have similar problems, and the issues are the exact problems that would be expected from exposure to oil.
Most of the oil released by the Deepwater Horizon was consumed rapidly by microbes in the Gulf. However, it’s clear from this study that the spill caused damage to the ecosystem that was still visible in the dolphins over a year later.
-JBB
Image credit: NOAA http://blogs.nature.com/news/2011/03/counting_corpses_underestimate.html