The Gulf of Mexico is a very unique place
geologically. It is home to the largest oil
and gas producing region in the continental
United States, and it is also one of the most
complex continental shelves in the world.
So I the Gulf of Mexico – the northern Gulf
of Mexico – we have oil and gas bearing
shales with a salt sheet underneath them and
a layer of sediment on top. And as these different
geological forces interact, we get cracks
in the oil-bearing shale, and we get natural
seepage coming out of the sea floor. So at
thousands of different places in the Gulf
of Mexico, oil and gas is naturally seeping
– very slowly – from the sea floor. In
those environments, we have some very special
communities of animals.
Among the things we’ve discovered over the
years is that there are mussels that get all
their carbon and energy from methane gas.
They can live entirely from methane gas. There
are tube ones – giant tube ones, meters
long – no mouth, no gun, no anus. They get
all their energy from hydrogen sulfide – a
gas that’s normally toxic, but it’s made
by bacterial living off oil in the sediments.
Now, another thing that came out of our studies
in the Gulf of Mexico is that the same bacteria
that are eating the oil, eating the methane
– as a byproduct of that, they’re creating
the chemical environment where rocks form.
And in places where you have oil seeps, you
have carbonates form. Most of the Gulf of
Mexico is mud – soft bottom. So in areas
where there are rocks are areas where special
communities can move in, and corals love rocks.
So we’ve found that in fact, most of the
deep corals in the Gulf of Mexico are associated
with oil seeps. We found that from east to
west across the Gulf, they’re actually quite
similar within a depth range. But we see very
different communities as we change in depths.
The biggest cutoff between the communities
occurs between 800 and 1,000 meters. Above
800, we have one type of coral community – predominantly
a community known as Lophelia pertusa, which
is a reef building coral that’s famous all
over the world for the structure and habitat
is provides for fish, which you don’t find
Lophelia deeper than 800 meters. Some other
hard corals cut in, and then deeper than about
1,400 meters, you find all kinds of soft corals,
bamboo corals and black corals dominating
the communities.
Now similar to that, the seep communities
change. Now they change in a different way
because shallow and deep, we still have mussels
with a symbiance. We still have tube worms,
but we have different species. We get an almost
complete species changeover at about 1,000
meters and some additional new species of
tube worms and mussels that come in at about
2,000 meters. So similar types of communities,
but completely different players, and all
new species – many of which were unknown
to science until we started working on these
sites.
All of the research we do is at depths greater
than it’s practical to do with scuba. So
when we go to sea, we use large ships and
some kind of a deep submergence facility.
We’ll use either remotely operated vehicles,
or an ROV, or a manned submersible – a submarine.
On our next expedition, we’ll be using the
Jason 2 ROV from Woods Hole and Graphic Institution,
which is a finely tuned remotely operated
vehicle built especially for science.
Now in addition to all the tools they’ll
bring with them – which will include precision
navigation capability, high definition video
cameras, and digital still cameras – we’ll
take a lot of our own specialized equipment
that we’ve built to work on the sea floor.
This will include devices that we’ve used
to put bands on tube worms so we could measure
their age over years; staining devices that
we’ve used to get yearly growth rates in
tube worms; specialized collection devices,
including one that we’ve nicknamed the Bush
Master, which is a giant hydraulically actuated
net that we can put around an intact coral
community or a tube worm community and collect
it for analysis in the lab.
Our project in October is part of a regularly
scheduled project. This project was designed
to explore and discover new deep water coral
sites in the Gulf of Mexico, characterize
those sites; but also conduct experiments
that will let us understand how the corals
work and why they are where they are. This
will be our main goal, will in fact be to
study the deep water coral communities of
the Gulf of Mexico. But in light of the recent
deep water horizon disaster, we’ll be supplementing
that work with some additional explorations
for sites in closer to the spill; and we’ll
be revisiting some of the sites we know very
well to see if we can detect any changes over
the last years since we were there last.
Now, we don’t really know what we’re going
to find when we go back out to visit these
communities, and we don’t know if they will
be impacted by the deep water horizon disaster.
But they certainly may have. Even though some
are adapted to oil, none of them are adapted
to dispersant. If there was a heavy exposure
to dispersant in any of the communities, this
could have some very serious toxic effects.
If in fact the dispersed oil forms small globules,
this could foul feeding appendages. It could
foul respiratory appendages and have a very
bad effect on these communities. Seminally,
if an area is a deep water plume of oil and
dispersant stayed cohesive, if it stayed intact,
oxygen in that area could be depleted. And
all of these animals require oxygen.
So certainly we don’t know that we’ll
see an impact. But there are a variety of
scenarios where we could, and the only way
to find out is to go down and take a look.
