Oil from the 2010 Deepwater Horizon disaster causes severe defects in the developing hearts of amberjack, bluefin and yellowfin tunas, federal scientists announced Monday.
Those heart defects likely mean an early death for those fish exposed to the oil, although what the further implications might be for the future of the species are unknown at this point. Bluefin tuna in particular are already a species in jeopardy, in part due to the demand from sushi restaurants.
Tuna and amberjack are large predatory fish that live in the open ocean, known as pelagic species. They normally spawn in spring and summer in the northern Gulf of Mexico. That means their developing offspring were floating in harm's way during the massive BP oil spill off the Louisiana coast nearly four years ago.
To test the impact the spill of nearly 5 million gallons of oil had on the fish, scientists exposed embryos of amberjack, bluefin and yellowfin tunas to samples from the Deepwater Horizon spill. It disturbed both the rate and the rhythm of the heart, the study found.
"The developing embryo's heart slows down right under our microscope," said Barbara Block, one of the authors of the study and a professor of biology at Stanford University. She called it "a significant cardiac injury" to the fish.
However, a BP spokesman questioned whether the study really shows the dire impact that the scientists suggest occurred as a result of the disaster.
"The paper provides no evidence to suggest a population-level impact on tuna, amberjack or other pelagic fish species in the Gulf of Mexico," said Jason Ryan of BP.
The oil concentrations used in the experiments do not match what was present in the gulf during the spill, Ryan said.
"In addition, the authors themselves note that it is nearly impossible to determine the early life impact to these species," he said.
"The multi-generational effects have not been rigorously studied yet," John Incardona of the National Oceanic and Atmospheric Administration, and lead author of the study, said during a news conference Monday.
The Deepwater Horizon disaster began on April 20, 2010, with an explosion aboard an oil rig off the Louisiana coast, killing 11 crew members. The rig sank, and two days later oil began spewing from the broken wellhead in water a mile deep. BP managed to shut it off at last on July 16, 2010.
The disaster occurred in one of the worst places in the world for an oil spill — 5,000 feet below the surface in a body of water that scientists admitted they knew little about, where it could potentially ruin both the seafood and tourism industries that depended on it.
Because of the size of the spill, the way it was handled and the lack of baseline science in the gulf, there's little previous research to predict long-term effects.
Although initially some pundits said the spill wasn't as bad as everyone feared, further scientific research has found a massive die-off among tiny creatures known as foraminifera that form the basis for the food web. Corals in the gulf died. Anglers hauled in crabs and fish with tattered fins and strange lesions. And dolphins in Louisiana continue dying.
The study published Monday builds on research that began with the Exxon Valdez oil spill 25 years ago, when scientists first discovered that recently spawned fish are especially vulnerable to the toxic effects of crude oil.
Scientists involved in Monday's study said they were mindful of the fact that it took eight years after the Exxon Valdez spill for the herring hatchery to collapse.
Craig Pittman can be reached at firstname.lastname@example.org or follow him on Twitter at @craigtimes.