Author: Xavier Pastor
Date: September 18, 2010
If you’ve been keeping up with the ship's log, you'll notice that these past two weeks have been as equally intense as the others. The departure of Oceana workers from Alaska and Washington and their hydrocarbon sensors was immediately compensated by the arrival of a new group of Spanish divers and the underwater robot (ROV) to Gulfport, Mississippi. Then we begin a new phase of the expedition: the visual exploration of the seabeds in the areas whose surface waters had been covered by oil for weeks.
The concentration of seamounts aptly named the Alabama Alps forms part of the rocky chain of the Pinnacles Reef that borders a large part of the continental shelf of that state and Mississippi, in the De Soto Canyon. This is the area where one of the most important hydrocarbon “veins” was detected.
The peaks of the Alabama Alps plunge to 68 meters depth. The northern slopes rise from the shelf, to only 90 meters. But on the southern slope, the beds plunge into the abyss, to roughly 1,000 meters. This group of pinnacles is known to harbour high levels of biodiversity. An exuberant oasis in an area that, because of inflow of sediments from the Mississippi and Mobile Rivers, among others, is covered by a layer of mud which is constantly disturbed by the trawling gear of the shrimp fleet in the Gulf of Mexico. We wanted to verify the initial impact on these seabeds caused by the Deepwater Horizon catastrophe, roughly 50 miles from the sight of the accident.
We had a 3D rendering of the Alabama Alps, but using the Latitude’s sensitive ecosonar and the Olex system installed in our computer, we’ve been able to construct a real image of the small mountain range, by repeatedly going over the area with the ship. Once the orography of these seamounts was determined in detail, we carried out up to eight dives with the ROV in different areas, crossing them in all directions and reaching the two main peaks with the robot. These dives were somewhat risky, because the pinnacles in this area live up to their names and -despite the fact that the sonar should have picked them up- they appear out of nowhere in front of the ROV’s lights, so the robot handlers and people in charge of the line that controls the ROV’s cable must move quickly to avoid crashing into the almost vertical walls, or even worse, to prevent the machine or its cable from getting caught in the numerous cracks and rocks that comprise this seabed.
There is no visual evidence to prove the ecosystem in these particular Alps has been seriously affected by the spill. The corals, gorgonians, crustaceans, fish and spectacular equinoderms, which are only a small part of the rich biodiversity of these seamounts, seem to continue with their lives without signs of degradation. We shouldn’t, however, get too confident. The invisible impacts of toxic hydrocarbons and the chemical dispersing products used to eliminate them from the public eye can manifest themselves in the medium or long term, in reproduction processes.
Once the Alabama Alps were explored in detail, we headed towards a new group of seamounts, the Schroeer Site. The weather is getting worse. We begin the dive and halfway down the cable, at roughly 350 meters depth, a huge wave hits the boat and water gets into an area that had been maintained dry up to now, hitting the ROV's electric generator and causing an overload. On top of that, the underwater robot is damaged. After verifying the damage, we head to Mobile Bay to have it repaired.
Meanwhile, activity on board the Oceana Latitude continues. We always have alternative work to begin, making sure we take advantage of the time. The Longitude is launched and, for the two days necessary to repair the ROV, the divers dive 20 miles from the boat, at different wrecks sunken on purpose to create artificial reefs. With the abundance of marine species, these places have become extraordinary laboratories in which the progressive impact of the invisible component of the BP spill can be determined.