When the Deepwater Horizon oil spill happened in 2010, we knew the fallout would be potentially catastrophic for marine life. Now, a new study shows how it may have led fish and other marine animals to develop physical abnormalities.
The research, called “Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish” and published this month in the journal Proceedings of the National Academy of Sciences, appears to show that the crude oil spill, the largest in U.S. history with an estimated four million barrels worth of oil leaking into the ocean, had several negative consequences for marine life.
The northern gulf is a critical breeding area for a number of warm water fish, including swordfish, blue marlin, Spanish mackerel, tuna and many that fall under the Pelagic bracket, meaning that they swim at mid-depth rather than preferring the surface or the ocean floor. These species tend to produce small, delicate embryos that are buoyant and so tend to drift at relatively the same level. They tend to spawn in the late spring and summer months, which unfortunately for them coincided with the April Deepwater spill.
Three species in total were studied, bluefin tuna, yellowfin tuna and a species of amberjack. The fish were exposed to two oil samples, one collected via surface-skimming operations in the Gulf of Mexico, and one taken directly from the source pipe of the damaged Deepwater Horizon wellhead, in concentrations that the scientists say are representative of spawning conditions at that time.
When the fish spawned, they found a number of abnormalities among the young. According to the study, those abnormalities included “reduction in the outgrowth of the finfolds or finfold blisters, a dorsal or upward curvature of the body axis, and marked reduction in the growth of the eye.” The team also observed numerous heart abnormalities, including an inability for the heart to keep a proper rhythm, heart defects and, they believe, an increased likelihood of heart failure.
What is worrying is that because tuna take eight years to mature, we are only four years out and so scientists have only seen the earlier stages of development. Due to this fact, and that tuna can only be caught once they reach the adult stage, researchers cannot yet know the mortality rates of the affected tuna, but there is cause to believe they will be significantly higher because of the physical abnormalities that will prevent them from swimming and feeding properly. Scientists also don’t yet know whether the spill will have affected the tuna’s ability to reproduce, something that future tests will have to analyze.
All that said, this study remains relevant for a number of reasons, chiefly that it establishes how crude oil, even in small quantities, can harm fish. The findings also support previous studies, namely one that tracked the effects of the 1989 Exxon Valdez 11 million gallons spill (this latest study was published 25 years on from that spill). In the case of the Exxon Valdez incident, the oil spill was geographically closer to the shore and so the main effect was of killing large swathes of coastal birds. However, developmental abnormalities and large die offs among adult fish were observed.
All this leads to the high probability that in another few years we’ll be seeing greatly depleted numbers of adult tuna, and many more fish species besides.
“The timing and location of the spill raised immediate concerns for bluefin tuna,” coauthor Barbara Block, Ph.D., is quoted as saying. “This spill occurred in prime bluefin spawning habitats, and the new evidence indicates a compromising effect of oil on the physiology and morphology of bluefin embryos and larvae. We now have a better understanding why crude oil is toxic, and it doesn’t bode well for bluefin or yellowfin embryos floating in oiled habitats. At the level of a single heart muscle cell, we’ve found that petroleum acts like a pharmacological drug by blocking key processes that are critical for cardiac cell excitability.”
When asked about the study, BP spokesman Jason Ryan told The New York Times that the study offered “no evidence” that the oil spill had impacted marine life because, he says, the scientists have used oil concentrations that do not reflect conditions after the Deepwater Horizon accident. “The oil concentrations used in these lab experiments were rarely seen in the gulf during or after the Deepwater Horizon accident. In addition, the authors themselves note that it is nearly impossible to determine the early-life impact to these species.”
The researchers have denied this, said that the concentrations are a fair representation based on data collected at the time of the accident.
The Washington Post notes that this study hits the headlines just as BP has regained its power to bid on federal oil and gas leases after the Environmental Protection Agency lifted its restrictions on the company — this despite heavy criticism from multiple quarters that BP hasn’t done anywhere near enough to stop such accidents happening in the future.
It also comes not long after BP attempted to dodge via the courts the financial repercussions of its catastrophic mistake. This has raised serious concerns that both the government and BP are still refusing to acknowledge the dangers associated with off-shore deepwater projects and the harm that manifests when things go so badly wrong.
Photo credit: Thinkstock.
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