This 26 September 2011 photo taken by Florida State University oceanographer Ian McDonald via an unmanned submersible vehicle, at a depth of 68 meters at the Alabama Alps Reef, offshore of Mississippi and Louisiana, 35 miles from the site of the Deepwater Horizon rig explosion and oil spill, shows Hypnogorgia pendula coral with injuries attributed to the oil spill. Photo: Ian MacDonald / Florida State University

By Cain Burdeau
27 October 2015

(Associated Press) – Gulf coral damage from the massive BP oil spill is more extensive than previously thought, according to a new study that revealed sick and dying corals in the rich, deep-water environment off the coasts of Alabama and Mississippi known as the Pinnacles.

Using remotely operated submarines, researchers explored the Pinnacle Reef in September 2011 and found more than 400 coral colonies were injured. Corals—such as sea whips, sea fans and black corals—were covered in a scum of dead tissues and oily residue. Some showed severe damage, such as bare skeletons and missing branches.

These colonies are found about 35 miles to 68 miles to the north of BP PLC's blown-out well, which spewed more than 130 million gallons of oil into the Gulf of Mexico in 2010. Previous discoveries of coral damage were found south of the BP well and in much deeper water. The coral in the Pinnacles live about 200 feet under the water surface.

The Pinnacles is a rocky outcropping on the Continental Shelf about 70 miles off the coasts of Mississippi and Alabama.

The study was conducted by a team of Florida State University researchers and federal scientists with the National Oceanic and Atmospheric Administration. It was also done as part of the work to assess damage from the spill, the so-called natural resources damage assessment. The study is set to be published in Deep-Sea Research, an oceanography journal.

The paper said the damaged coral showed signs of injury from an "acute, isolated event rather than ongoing natural processes." It based this conclusion on previous explorations that looked at the corals between 1997 and 1999, which found the corals were mostly healthy.

"We saw many injured colonies," said Ian MacDonald, an oceanographer at Florida State University. He is one of the authors of the study.

He believes a much larger area of the Pinnacles most likely suffered similar damage.

"The area we have looked at so far is only the tip of the iceberg," he said. [more]

Study shows extensive coral damage related to BP spill

ABSTRACT: Pathologies in over 400 octocoral and antipatharian colonies were quantified in the aftermath of the DWH oil discharge. Observations were made in September 2011 at water depths of 65 to 75 meters in the Pinnacle Reef trend area offshore from Mississippi and Alabama, Gulf of Mexico, using a digital macro camera deployed from an ROV to examine the coral populations for injury at two principal sites: Alabama Alps Reef (AAR) and Roughtongue Reef (RTR). Taxa observed to exhibit injury included gorgonian octocorals Hypnogorgia pendula, Bebryce spp., Thesea nivea, and Swiftia exserta, the antipatharian Antipathes atlantica, and the sea whips Stichopathes sp., and Ellisella barbadensis. The most common type of injury was a biofilm with a clumped or flake-like appearance covering sea-fan branches. Extreme injuries were characterized by bare skeletons, broken and missing branches. Comparing the 2011 results to previous photo surveys of the same study sites between 1997 and 1999, we found significantly more occurrences of injury in 2011 among taxa with growth forms>0.5 m. We hypothesize that Tropical Storm Bonnie facilitated and accelerated the mixing process of dispersant-treated hydrocarbons into the water column, resulting in harmful contact with coral colonies at mesophotic depths. Analysis of total polycyclic aromatic hydrocarbon (tPAH) concentrations in sediments at AAR and RTR found levels elevated above pre-discharge values, but orders of magnitude below toxicity thresholds established for fauna in estuarine sediments. The tPAH concentrations measured in octocoral and echinoderm tissue samples from AAR and RTR were detectable (mean values ranged from 51–345 ppb); however, bioeffect thresholds do not currently exist with which to evaluate the potential harm these levels may cause. Our findings indicate that coral injuries observed in 2011 may have resulted from an acute, isolated event rather than ongoing natural processes.

Coral injuries observed at mesophotic Reefs after the Deepwater Horizon oil discharge



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