New ECOGIG publication summarizes spill impacts on Gulf's deepwater ecosystems

New ECOGIG publication summarizes spill impacts on Gulf's deepwater ecosystems
Deepwater corals and brittle stars (ophiuroids) which are thought to have protected the corals from oil damage and hydroid colonization after the Deepwater Horizon accident. Photo courtesy of Cherisse Du Preez.

October 25, 2016

A recent ECOGIG publication in the GoMRI special issue of Oceanography summarizes the ecological impacts (to date) of the 2010 Deepwater Horizon accident on the deep ocean ecosystems of the Gulf of Mexico.

The deep ocean is a remote place that is difficult to access and is largely unexplored by humans. Documenting the impacts of the DWH accident in this region is extremely difficult, but of the utmost importance as organisms found there serve vital roles in deep ocean ecosystems, some of which are not fully understood at this point.

Ninety percent of the volume of the Gulf of Mexico is contained in waters deeper than 200 meters (approximately 600 feet)- the maximum depth that sunlight can penetrate the water and the depth that is considered to be the start of the deep ocean. The Deepwater Horizon (DWH) accident occurred at a depth of approximately 1500 meters (4500 feet) - an area that contains more ecological diversity than any other part of the Gulf of Mexico. A recent ECOGIG publication by Dr. Charles Fisher (ECOGIG), Dr. Paul Montagna (C-IMAGE II) and Dr. Tracey Sutton (DEEPEND) in the GoMRI special issue of Oceanography reviewed Natural Resource Damage Assessment (NRDA) studies in an attempt to understand the ecological impacts that the DWH accident had on the deep ocean ecosystems of the Gulf of Mexico.

Deep ocean communities are made of up three community levels- pelagic (open ocean), demersal (near the bottom) and benthic (on or in the bottom). These three communities are intricately linked through complex food webs- severe impact to one can have a ripple effect through the other two. NRDA studies show that oil from the DWH accident was incorporated into the pelagic food web. This caused a reduction in the number of organims that eat phytoplankton, leading to a large phytoplankton bloom that sank to the bottom, taking some of the oil with it. Fish larvae were killed, losing an entire generation. Cetaceans (whales and dolphins) were either killed or left the area of the spill completely. Benthic animals living in the sediment suffered a large decrease in diversity due to the oil. Deepwater corals, anchored to the seafloor, were especially vulnerable to the falling oil which coated them in a layer of flocculent material. The effects of accident were devasting in the deep ocean and found as far as 14km (approximately 9 miles) from the wellhead.

The deep ocean is a remote place that is difficult to access, so it is largely unexplored by humans. Documenting the impacts of the DWH accident in this region is extremely difficult, but of the utmost importance as organisms found there serve vital roles in deep ocean ecosystems, some of which are not completely understood at this point. The deep Gulf of Mexico in particular contains vital foraging grounds for commercially important fish and spiritually valued cetaceans. The deep ocean is extremely efficient at dealing with human generated waste- absorbing up to 25% of our carbon emissions and helping to degrade some of the oil released during the DWH accident. There has also been a number of educational and scientific advancements to come out of studying the deep ocean. It is vital that we protect this valuable resource so that we can discover all there is to know about it.

To read more, you can access the entire article, titled "How Did the Deepwater Horizon Oil Spill Impact Deep-Sea Ecosystems?" herewhich appeared in the special Gulf of Mexico Research Initiative (GoMRI) funded issue of Oceanography.

 

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