NOAA: Crude oil from the 2010 Deepwater Horizon disaster causes severe defects in the developing hearts of bluefin and yellowfin tunas, according to a new study by a team of NOAA and academic scientists. The findings, published in the Proceedings of the National Academy of Sciences on the 25th anniversary of the Exxon Valdez oil spill, show how the largest marine oil spill in United States history may have affected tunas and other species that spawned in oiled offshore habitats in the northern Gulf of Mexico. Atlantic bluefin tuna, yellowfin tuna, and other large predatory fish spawn in the northern Gulf during the spring and summer months, a time that coincided with the Deepwater Horizon spill in 2010. These fish produce buoyant embryos that float near the ocean surface, potentially in harm’s way as crude oil from the damaged wellhead rose from the seafloor to form large surface slicks. The new study shows that crude oil exposures adversely affect heart development in the two species of tuna and an amberjack species by slowing the heartbeat or causing an uncoordinated rhythm, which can ultimately lead to heart failure.”