Tuna Exposed to Oil and Toxins Suffer Cardiac Arrest

tunaThough scientists have know that fish that are exposed to toxins from oil spills suffer from cardiac arrest, they were not entirely sure how until recently. A study published in the journal Science on Thursday explains exactly they studied bluefin tuna to determine what happens when the fish are covered in oil.

Authors of the study from Stanford University and the National Oceanic and Atmospheric Administration (NOAA) have been studying the effect of the oil spill that occurred in the Gulf of Mexico in 2012 from the Deepwater Horizon. Barbara Block and her team specifically looked at the bluefin tuna, which has dropped 64 percent in population since 1970.

Scientists extracted heart cells of tuna and exposed them to oil at the Tuna Research Conservation Center in California. What they discovered is that polycyclic aromatic hydrocarbons (PAHs) disrupt the molecule movement in the pores of heart cells, thus restricting blow floor to the heart. Irregular heartbeats follow, as the heart slows down and weakens.

Even low levels of exposure that do not immediately kill the fish result in a hindered ability to swim due to deformed hearts. Their torpedo-shaped bodies are normally known for their speed, however. Bluefin tuna can get as big as 12 feet long and weigh in as much as 1,400 pounds, but the average tuna is closer to six feet long and 550 pounds. Under healthy circumstances, they have a life expectancy of 35.

According to the experts at NOAA, the findings of this study are relevant to more than just bluefin tuna. It is likely that other animals, and even humans, could experience a heart attack if exposed to oil pollutants.

On Apr. 20, 2010, four million barrels of crude oil spilled into the Atlantic when an explosion caused an oil rig sunk near the Gulf of Mexico, killing 11 people. It is considered the worst oil spill to date in the U.S. The BP pipeline spilled gas and oil through the ocean for 87 days, until the well was finally capped on June 15. It is estimated that over 200,000 gallons were spread into the ocean each day.

Few U.S. oil spills can compare to the damage that the BP pipeline caused. In June of 1979, an oil well collapsed and caused an explosion, spilling more than 140 million gallons into the Bay of Campeche in Mexico. On Mar. 24, 1989, a reef collision caused the Exxon Valdez to spill 10 million gallons near Alaska. On Dec. 15, 1976 the Argo Merchant spilled 7.7 million gallons and in 2005, Hurricane Katrina resulted in seven millions gallons spilled in New Orleans.

But the damage caused by the oil spill in the Gulf of Mexico goes beyond the immediate effects. The National Wildlife Federation (NWF) states that dolphins, sea turtles and fish are continuing to die off following the 2010 oil spill.

Several years after the oil spill that exposed the natural environment and countless animals to harmful pollutants and toxins, the negative effects continue. Residue still exists, causing health concerns for the dying population of fish. This study provides deeper insight as to how the oil affects the fish hearts. Previous studies found that the oil caused a heart problem, but the details were unclear. Oil and toxins are the reason for the decline in the tuna population because they cause them to suffer from cardiac arrest.

By Tracy Rose

Sources:

Christian Science Monitor
Los Angeles Times
Science Recorder
National Geographic
Ocean Portal

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