Gulf Tuna Have Heart Problems

painting courtesy, National Geographic

Yet another dirty impact of the Deepwater Horizon spill in the Gulf of Mexico has been discovered. Bluefin and yellowfin tuna (Thunnus thynnus, Thunnus albacares), apex predators, are suffering severe heart problems caused by spilled crude oil. That is the conclusion of a study released by NOAA. Crude oil causes the heartbeat of larvae and embryos to slow down or beat arrhythmically. If they survive contact with oil, their ability to swim fast is impaired. Severely affected tuna are likely to have died of heart failure soon after hatching. The spill occurred during the critical spawning season when fish embryos float near the surface. The threshold for developmental defects are low, approximately 1-15ppb. Because of the difficulty of capturing live embryos near the spill site. Contaminated water was brought to tuna hatcheries in Australia and Panama where scientists emulated conditions in the Gulf of Mexico. NOAA has been researching the effects of crude oil toxicity on fish for more than two decades. Researchers suspect that similar effects have occurred in species of swordfish, marlin, and mackerel.


More: The much abused Gulf took another hit on Saturday when an oil barge collided with another vessel and breached one of its tanks. 168,000 gallons of RMG 380, a particularly viscous marine fuel oil, spilled into Galveston Bay.  Because it is heavy, most of it will sink to the bottom, but because it is sticky it will smother wildlife and persist in the environment for a long time.  The collision occurred in fog when the towboat M/V Miss Susan and her barges hit a bulk tanker, Summer Wind  in the Houston Ship Channel.  Coast Guard records show the Miss Susanhas been involved in twenty collisions in the past twelve years.   The latest mess from the oil industry coincides with peak migration of shorebirds in the region.  Audubon says more than 100 oiled birds have been found, and there are mortalities [photo credit: Houston Chronicle]. Galveston Bay is one of the most biologically productive areas in the nation, second only to Chesapeake Bay. Visitors come from all over the world to view its diverse wildlife. Houston Audubon scientists have found dead birds on the Bolivar Flats Shorebird Sanctuary, just two miles from the collision spot. During migration now underway, more than 100 species of birds rest, forage or breed at the sanctuary including the endangered piping plover. Any marine specie that comes to the surface such as dolphins and turtles will also be impacted. Rough weather has defied efforts to skim the surface and remove most of the gunk so more than half of it has swept into the Gulf of Mexico.