A new study conducted by he National Oceanic and Atmospheric Administration has found that the BP oil spill may be causing heart problems in some commercial fish.

Dr. John Incardona, a NOAA research toxicologist, said the research found fish exposed to lower concentrations of oil suffered from abnormal heartbeats.

"Fish that looked morphologically normal on the outside still had abnormal heart rhythms or arrhythmia," Incardona said.

Large, deepwater fish — like tuna and amberjack — that had been exposed to higher levels of oil exposure from the 2010 Deepwater Horizon disaster were found to have "severely malformed and malfunctioning hearts," Incardona said, adding that oil's impact on the fish is based on the level of exposure.

"The Deepwater Horizon oil disturbed the heart rate and rhythm of each of the species we tested in a concentration-dependent manner," Incardona said. "That is, the effects increased in severity as the oil concentration was increased."

BP has disputed the findings, claiming oil levels used in the study were "rarely seen in the Gulf."

Incardona said the heart defects could lead to widespread losses of popular deep-sea fish in the Gulf.

"Fish would in all likelihood survive the immediate effects of oil exposure," Incardona said, "but would also probably end up with a mild heart malformation, reducing their aerobic performance — which for fish means swimming — later on in life, which could lead to premature death."