This photomosaic is a careful compilation of multiple images taken of a mussel bed in AT340 with a downward looking still camera in 2006. Click image for larger view and image credit.
Seafloor community of tubeworms, mussels, shrimp and a crab in GC852. Click image for larger view and image credit.
Mission Plan
Chuck Fisher
Penn State University
This year’s mission includes two types of activities, which together will advance our understanding of the sea floor communities that live in association with hydrocarbon seepage and hard grounds in the deep Gulf of Mexico (GoM). We will revisit about half of the sites we discovered last year, complete our characterization of these impressive sites, and also collect time series data that will provide important information on how fast seep animals grow and how the deep communities change over time. The second objective will be to explore 3-5 new areas and to characterize any new sites and communities discovered. We have identified likely sites for these exploratory dives and will use them to fill in key pieces to the puzzle of the seep animal and coral distribution patterns in the deep Gulf of Mexico. All of the sites we will study are in areas where energy companies could soon begin to drill for oil and gas. Our mission will provide essential information on the ecology and biodiversity of these deep-sea communities to regulatory agencies and energy companies as the quest for oil moves into deeper and deeper water.
The largest oil reserves in the continental United States are found in the Gulf of Mexico. The Minerals Management Service (MMS) of the US Department of the Interior oversees the responsible extraction of these natural resources and has been supporting the study of the hydrocarbon seep communities since the early 1980’s. Up until a few years ago these studies were focused on communities found between 500 and 1000m depth.
Meanwhile, energy companies have continued to develop the technology for extraction of oil and gas from deeper and deeper water, and now have the capability to drill oil wells in all water depths in the GoM. This is one of the reasons that the Mineral Management Service and NOAA have funded our study, and also one of the reasons that our project received a Cooperative Conservation Award from the Department of the Interior this year for this project.
On June 4th, our plan is to depart on the NOAA Ship Ronald Brown from Fort Lauderdale, Florida to begin our 2-day transit to our first dive site. We will begin our operations at one of the lushest sites we discovered last year, which we call AT340 after the MMS lease block it is in: Atwater Valley lease area, block 340. When we first arrive we will deploy an array of navigational transponders that will allow us to make detailed maps of the sea floor and always know where we are (within a meter or two). The Jason II ROV, designed by the Woods Hole Oceanographic Institution’s Deep Submergence Laboratory, can work around the clock, so as soon as our transponders are ready to go we will launch the ROV and begin our bottom operations. We do not want to stop the bottom operations just to retrieve collections so we will be using an “elevator” to send our collections back to the surface without recovering the ROV. On board the ship, teams of scientists will be working on these valuable collections; analyzing the chemistry and geology, identifying the animals, and studying the microbial communities.
A red gorgonian from the Coral Garden area in GC852. The eight tiny tentacles on each polyp place this coral in the Octocorallia. You can also see an anemone attached to the coral and a small galatheid crab in the background. Click image for larger view and image credit.
The next site we will visit will be “GC852” (in Green Canyon lease area, block 852). In addition to lush communities of tubeworms and mussels, we also discovered a beautiful coral community at this site. We have several studies to finish up at GC 852, but when we are finished we will change the types of equipment we have on the ROV and begin the most exploratory phase of the expedition. We will dive on at least 3 new sites, and perhaps as many as 5. What we do and how long we spend working on each site will depend on what we find. These are sites never before seen by human eyes, and we will have to adapt our plans as we go.
About half-way through the expedition we will have an at-sea exchange of personnel. Six new scientists will board a transfer ship in Florida and meet us about 150 miles off the coast of Louisiana. Six other scientists will get off our research ship and take the “taxi” in to a port in Texas and fly back to their home laboratories. Meanwhile, the rest of us will continue our exploration and study of the deep seep sites. Our plan is to finish up with the sites offshore of Mississippi and Louisiana by about our third week at sea, and then move 200 miles further to the west and make a series of dives at three different sites in the Alaminos Canyon lease blocks, off the coast of Texas.
A few of the hard and soft corals in the Coral Garden area in GC 852. Click image for larger view and image credit.
A large aggregation of tubeworms (mostly Escarpia laminata) attached to carbonate blocks at 2200 m depth in Alaminos Canyon lease block 645. In the fore-ground is the Bushmaster collection device attached to the front of the Alvin submersible. Click image for larger view and image credit.
At AC 818, in 2,800m water, we have a tubeworm growth study underway and have also seen, but not collected, what is almost certainly a new species of clam with sulfur-oxidizing symbionts. Another site, AC 645, was the first deep water hydrocarbon seep community discovered in the GoM, and where we banded some tubeworms and mapped mussel communities way back in 1992. We found our 1992 study area during the last dive of the 2006 expedition, so we will return here and document the changes in the communities and growth of the worms that has occurred over the last 16 years! Another site, in AC 601, hosts a large lake of brine that covers about 17,000 square meters of the sea floor. The sediments here had some of the most extreme chemistry and strange microbial activity of any site we visited, and the chemists and microbiologists are excited for another set of samples from this site.
By the end of this expedition, we will have a very good understanding of the biodiversity of the communities on the deep hard grounds and seeps in the Gulf of Mexico, and their relation to the complex geology and geochemistry of the region. We will have the samples needed to begin unraveling the relationships among the populations at different sites and the data to estimate growth rates and calculate ages of some of the key species. We will also have collected a large quantity of “ground-truth” information relating what can be detected by remote sensing to what is actually present on the sea floor. This will provide us with a vastly improved ability to predict the occurrence of seep and coral communities in the deep sea, based on geophysical, geochemical, and satellite data collected from on and above the surface of the ocean.
