deepwater horizon coral
July 30, 2014

Scientists Discover New Coral Communities Affected By Deepwater Horizon Oil Spill

redOrbit Staff & Wire Reports - Your Universe Online

The environmental impact of the Deepwater Horizon oil spill is more widespread than previously believed, as experts have located two additional deep-water coral communities that were damaged by the 2010 disaster.

The discovery was made by a team of researchers led by Penn State University biology professor Charles Fisher, and is detailed in a paper published online Monday by the Proceedings of the National Academy of Sciences.

“The footprint of the impact of the spill on coral communities is both deeper and wider than previous data indicated,” Fisher explained in a statement. “This study very clearly shows that multiple coral communities, up to 22 kilometers from the spill site and at depths over 1,800 meters, were impacted by the spill.”

According to the study authors, since most of the oil leaked into the Gulf of Mexico following the oil rig’s explosion has since dissipated, they needed to turn to alternative methods of identifying marine creatures affected by the spill. Fisher and his colleagues used the conditions at a coral community previously identified as having been impacted by the spill as a blueprint against which to measure the impact of the spill in newly discovered coral communities.

While the remains of most species affected by the spill will quickly disappear from the ocean floor, corals form a mineralized skeleton that can remain for years following the organism’s death. The scientists compared the new coral communities with one discovered shortly after the oil spill, using it as a model to track the progression of damage.

“One of the keys to coral's usefulness as an indicator species is that the coral skeleton retains evidence of the damage long after the oil that caused the damage is gone,” said Fisher. “We were able to identify evidence of damage from the spill in the two coral communities discovered in 2011 because we know exactly what our model coral colonies, impacted by the oil spill in 2010, looked like at the time we found the new communities.”

There are few corals located deep in the Gulf of Mexico’s waters, but since they act as an indicator species and can be used to track the impact of oil spills and other ecological disasters, taking the time to find them can help scientists secure essential data. Fisher’s team went looking for coral communities located at depths of over 1,000 meters, some of which were smaller than the size of a tennis court, in order to capture high-resolution images of them.

The study authors used 3D seismic data from the US Bureau of Ocean Energy Management to identify 488 potential coral habitats in a 40 km radius around the site where the spill occurred. Next, they narrowed the list down to 29 sites deemed most likely to contain corals that were damaged by the spill, and used towed camera systems and an autonomous underwater vehicle to survey the region and collect images from just above the ocean floor.

Finally, Fisher and his colleagues used an ultra-heavy-duty remote-operated vehicle (ROV) to collect high-resolution images of corals at the sites where they were discovered. While searching for the coral communities impacted by the Deepwater Horizon oil spill, they also discovered two coral sites that had been entangled with commercial fishing line, which they called a reminder that the region is also being impacted by various human activities.

“With the cameras on board the ROV we were able to collect beautiful, high-resolution images of the corals. When we compared these images with our example of known oil damage, all the signs were present providing clear evidence in two of the newly discovered coral communities of the impact of the Deepwater Horizon oil spill,” Fisher said.

Fisher was joined by Penn State colleagues Pen-Yuan Hsing, Samantha P. Berlet, Miles G. Saunders and Elizabeth A. Larcom on the study, as well as Carl L. Kaiser, Dana R. Yoerger and Timothy M. Shank of the Woods Hole Oceanographic Institution; Harry H. Roberts of Louisiana State University; William W. Shedd of the Bureau of Ocean Energy Management; Erik E. Cordes of Temple University; and James M. Brooks of TDI-Brooks International Inc.

Their research was supported by the Assessment and Restoration Division of the National Oceanic and Atmospheric Administration (NOAA), the Gulf of Mexico Research Initiative funding to support the Ecosystem Impacts of Oil and Gas Inputs to the Gulf (ECOGIG) consortium administered by the University of Mississippi, and BP as part of the Deepwater Horizon Oil Spill Natural Resource Damage Assessment.