From Wildlife Extra:
The effects of the Deepwater Horizon oil spill that are still emerging
A team led by Charles Fisher from Penn State University in the US has found two additional damaged coral communities up to 22km away from the original site and at depths of more than 1,800m, reports Science Daily.
Fisher’s team compared damaged communities found around the time of the oil spill with the new ones. The former has provided a useful model for the progression of damage caused by the spill over time.
“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.”
Corals are sparse in the deep waters of the Gulf of Mexico, but because they act as an indicator species for tracking the impact of environmental disasters like the Deepwater Horizon blowout, the effort to find them pays off in useful scientific data.
The team used 3D seismic data from the Bureau of Ocean Energy Management to identify 488 potential coral habitats in a 40 km radius around the spill site. From that list they chose the 29 sites they judged most likely to contain corals impacted by the spill.
Towed camera systems and an autonomous underwater vehicle then came into play, which they programmed to travel backwards and forwards across specific areas collecting images of the sites from just metres above the ocean floor.
“We were looking for coral communities at depths of over 1,000m that are often smaller than the size of a tennis court,” said Fisher.
“We needed high-resolution images of the coral colonies that are scattered across these communities and that range in size from a small houseplant to a small shrub.”
In searching for coral communities impacted by the Deepwater Horizon oil spill, the team also found two coral sites entangled with commercial fishing line.
These additional discoveries serve as a reminder that the Gulf is being impacted by a diversity of human activities.