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Deepwater Horizon oil left once-speedy fish unfit to catch prey Deepwater Horizon oil left tuna, other species with heart defects likely to prove fatal
(35 minutes later)
Oil that spewed from BP’s Deepwater Horizon spill caused heart deformities in embryos and young tuna in the Gulf of Mexico, potentially slowing some of the fastest swimmers in the ocean, and impeding their ability to catch prey and survive, a new study has found. The BP Deepwater Horizon oil spill struck at the very heart of fish, a new study says. Exposed to millions of gallons of crude, young tuna and amberjack, some of the speediest predators in the ocean, developed heart defects that are likely to limit their ability to catch food.
The implications to the ecosystem and the commercial fishery are stark, said the authors of the study, led by the federal National Oceanic and Atmospheric Association. The April 2010 spill occurred when tuna were in the area to spawn. Millions of embryos were affected at the most sensitive time of life, when they are so fragile it is possible to see through them. The findings of the study, led by the National Oceanic and Atmospheric Administration, have grim implications for the future of yellowfin and bluefin tuna, as well as amberjack, that were embryos, larvae or juveniles when the spill occurred during tuna-spawning season in the northern Gulf of Mexico in April 2010.
A similar study last month studied the impact of oil on the mechanics of embryonic tuna hearts — how, for example, heartbeats were affected. This study was designed to look at what happened to the development of the hearts of embryos, larvae and juveniles of bluefin and yellowfin tuna, as well as amberjack, when exposed to oil identical to that of the Deepwater spill. The exposure left the hearts deformed and unable to function correctly. Embryos are highly sensitive, so fragile that it is possible to see through them. When scientists re-created the conditions of the spill in a lab, exposing tuna and amberjack in the developmental stage to an oil slick, they observed “a slowing of their heartbeats,” said Barbara Block, a biology professor at Stanford University who co-authored the study.
“They’re not going to be able to survive,” said Nat Scholz, leader of the ecotoxicology program at NOAA’s Northwest Fisheries Science Center in Seattle. “They’re going to hatch, be unable to feed and die. You’re going to be losing those fish from the adult spawning population.” “They’re not going to be able to survive” as they develop into adult fish, said Nat Scholz, leader of the ecotoxicology program at NOAA’s Northwest Fisheries Science Center in Seattle. “You’re going to be losing those fish from the adult spawning population.”
“We see a slowing of their heartbeats,” said Barbara Block, a biology professor at Stanford who co-authored the study. The oil caused cardio toxic injury to bluefin tuna, yellowfin tuna and amberjack, ultimately disrupting vital functions that pump blood through the bodies of the fish. The study — “Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish” — was published Monday in the Proceedings of the National Academy of Sciences on the 25th anniversary of the Exxon Valdez oil spill in Alaska’s Prince William Sound.
Tuna and amberjack are not the only species impacted, the study said; Deepwater Horizon’s crude oil also impacts the developing hearts of large predatory pelagic fish. The northern gulf is a critical spawning area and habitat for rearing young and is used by a wide range of pelagic fish, including mahi mahi, swordfish, king and Spanish mackerels, sailfish, blue marlin, and cobia. Pelagic fish are those that swim at mid-depths, neither at the surface or at the bottom. Research conducted on fish after the 1989 Exxon Valdez spill had similar findings, but the exposed population then was smaller because the 11-million-gallon spill collected closer to the shore, killing an estimated 250,000 birds.
The findings were published Monday in the Proceedings of the National Academy of Sciences. NOAA’s study comes as BP has regained the ability to bid on federal oil and gas leases; the Environmental Protection Agency recently lifted a ban on the company. The oil giant filed a lawsuit in a Texas court last August, arguing it had been sufficiently punished for the spill.
The study is part of the Natural Resource Damage Assessment that is seeking to determine the full impact of the Deepwater Horizon disaster and assess the price of restoring the gulf following the largest accidental marine oil spill in the history of the petroleum industry. The study is part of the Deepwater Horizon Natural Resource Damage Assessment, which seeks to determine the impact of the disaster and assess the price of restoring the gulf after the largest accidental marine oil spill in history.
It was released Monday, on the 25th anniversary of the Exxon Valdez oil spill in Alaska’s Prince William Sound, the second-largest in the United States. Up to 11 million gallons of oil flowed into pristine waters, killing about a quarter-million birds, according to some estimates. The other authors were John Incardona, a research toxicologist at NOAA’s Northwest Fisheries Science Center, and Martin Grosell, a biology professor at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.
Four years after an estimated 4 million barrels burst into the gulf, biologists still do not know how many fish were killed or mortally damaged. The northern gulf is a critical spawning area for a wide variety of warm-water pelagic fish, including mahi-mahi, swordfish, blue marlin, sailfish, cobia and king and Spanish mackerel. Pelagic fish are those that swim at mid-depth, neither at the surface or at the ocean bottom.
Tuna, for example, take eight years to mature, the point at which they can be commercially caught. Tuna from larvae at the time of the spill are four years old and do not factor into fishing totals. Pelagic fish produce small, buoyant embryos that develop quickly but are extremely delicate. During the study, they were exposed to two oil samples collected from surface-skimming operations in the open Gulf of Mexico and from the source pipe attached to the damaged Deepwater Horizon wellhead.
The study is key because it demonstrates oil’s impact on the hearts of vertebrate and could help explain a future die-off of tuna. In the three species studied, abnormalities were clear. Heart contractions were observed and asymmetry was apparent. The deformities continued after the eggs hatched.
“Now you’ve got two studies: one that shows how . . . chemicals in petroleum affect cells and an organism study where you can see the slowing of the heart,” said Block, who co-founded the Tuna Research and Conservation Center at the Monterey Bay Aquarium in northern California. “Morphological 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 study said.
Four years after an estimated 4 million barrels of oil burst into the gulf, biologists still do not know how many fish were killed or mortally damaged.
Tuna take eight years to mature, the point at which they can be commercially caught. Only four years have passed since the spill, so fish that were embryos, larvae or juveniles at the time of the spill have not reached adulthood and cannot be caught. Because the fish at this stage are rarely seen, their mortality cannot be reflect by fishing totals or other surveys.
But the study is important because it demonstrates oil’s impact on the hearts of fish and could help explain a future die-off of tuna.
“Now you’ve got two studies: one that shows how . . . chemicals in petroleum affect cells and an organism study where you can see the slowing of the heart,” said Block, who co-founded the Tuna Research and Conservation Center at the Monterey Bay Aquarium in Northern California.
“We now have a better understanding of why crude oil is toxic, and it doesn’t bode well for the bluefin or yellowfin embryos floating in oiled habitats,” Block said.“We now have a better understanding of why crude oil is toxic, and it doesn’t bode well for the bluefin or yellowfin embryos floating in oiled habitats,” Block said.
Environmental groups welcomed the study as another breakthrough. “This study, and others like it, helps us to see what can’t be seen with the naked eye,” said Jacqueline Savitz, vice president for U.S. oceans at the nonprofit group Oceana. Environmental groups welcomed the study. “This study, and others like it, helps us to see what can’t be seen with the naked eye,” said Jacqueline Savitz, vice president for U.S. oceans at the nonprofit group Oceana.
“Not only is oil toxic to fish, its effects are not limited to small fish. In fact, they extend to the largest and most commercially valuable fish we know: tuna,” she said. “For a species like bluefin tuna, whose populations have crashed due to overfishing and are fighting to rebuild their former abundance, BP’s oil was a shot to the heart.”“Not only is oil toxic to fish, its effects are not limited to small fish. In fact, they extend to the largest and most commercially valuable fish we know: tuna,” she said. “For a species like bluefin tuna, whose populations have crashed due to overfishing and are fighting to rebuild their former abundance, BP’s oil was a shot to the heart.”
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