During the spring and summer of 2010, the BP Deepwater Horizon disaster released over 4 million barrels of crude oil into the Gulf of Mexico. This was an unprecedented amount of toxic material discharged into the Gulf, and scientists have been researching its impacts on marine and coastal wildlife ever since. One of the species of concern is the imperiled Atlantic bluefin tuna, which was spawning at the time and location of the BP disaster.

In a new study, scientists from Stanford University and the National Oceanic Atmospheric Administration (NOAA) discovered that crude oil, specifically polycyclic aromatic hydrocarbons (PAHs), disrupts the cellular pathway that allows juvenile bluefin and yellowfin tuna heart cells to beat effectively. This causes a slowed heart rate, reduced ability of muscular heart tissue to contract, and irregular heartbeats that can lead to cardiac arrest and death.

Crude oil is known to be toxic to the developing hearts of fish embryos and larvae, reducing the likelihood that those fish will survive. But until now, the details of how crude oil harmed fish hearts were unclear.

How Crude Oil Slows the Heartbeat

The heart in vertebrates is made up of a collection of individual cells that interact to give the heart its ability to beat and pump blood. To beat effectively, the heart cell must move essential ions like potassium and calcium through channels into and out of the cell quickly. Very low concentrations of crude oil block these channels in heart cell membranes, which ultimately slow the fish’s heartbeat.

The ion channels observed in tuna heart cells are similar to the ion channels found in heart cells of many animals, including humans. This study provides evidence as to how petroleum products may be negatively affecting cardiac function in a wide variety of animals.

Implications for Other Species

After the BP Deepwater Horizon disaster, other fish, such as red snapper, spawned in offshore waters, these spawning habitats were potentially oiled as a result of the disaster. This raises the possibility that eggs and larvae of many species, which float near surface waters, were exposed to oil. The potential harmful impacts of the BP disaster on young fish are still being investigated.

Looking at the big picture, these new findings demonstrate how petroleum-derived chemical pollution from the BP oil disaster and other sources — such as urban stormwater runoff — could affect coastal and marine species in the Gulf or elsewhere. This study raises the concern that exposure to PAHs in many animals – including humans – could lead to cardiac arrhythmias and bradycardia, or slowing of the heart.

Restoring the Gulf of Mexico

This study is groundbreaking for many reasons. For one, it offers insight into how crude oil from the BP disaster could impact wildlife in offshore waters. Second, the study points to the types of data that scientists need to collect in order to monitor the environment’s health and recovery before and after an oil spill – like a doctor taking vital signs to monitor a patient’s health prior to and after a heart attack.

And lastly, it underscores the importance of funding long-term ecosystem monitoring to understand how daily pollution such as stormwater runoff and air pollution as well as large scale human-caused disasters affect the health of wildlife, habitats and humans.

In light of this significant discovery, it is essential that we continue to research and monitor the impacts of the BP Deepwater Horizon oil disaster so that we may understand the full scope of injury and implement strategies to restore the Gulf of Mexico to its former resilience and beauty.