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Tuesday August 3, 2004 17:27:46
GMT, 10:27am ship time
Denson Seamount 53N 137W
What a basket of goodies! No doubloons
or diamonds, but six corals, four rocks,
one crab, an anemone, and a hula suction
(to be explained
later) were in yesterday's haul. As Alvin
rolled back into its burrow and the A-framewas
secured for the night, the scientists
pounced on the basket. (I am still looking
for the perfect collective noun for a
group of scientists - gaggle? flock? murder?)
Alvin's "basket" is actually
a metal platform to which various sampling
receptacles are attached, depending on
the science goals of the cruise. This
time, it's all about rocks, corals, and
hula skirts. And I should explain that
for all the hi-tech wizardry inside the
sub, what goes on the basket outside is
usually concocted from milk crates, cable
ties, and (believe it or not) rubber bands.
So for this cruise, we have two milk crates,
subdivided by plastic mesh, for rock collection;
two "bioboxes" containing sawn-off
pieces of PVC pipe, a rack of Niskin bottles
for water collection, and something that
looks for all the world like a carpet
cleaning machine.
The last item is actually a rotating
multichambered container with a vacuum
hose attached. The hose slurps up a sample
and deposits in one of the chambers, then
the container rotates, and is ready to
receive the next sample. Slurping is important
on this cruise, because we are hunting
for an eminently slurpable quarry - the
hula skirt. This is a fringe-like material
adorning the stem of large black corals
observed on previous cruises. It sways
sensuously in the current, and you can
almost hear the Hawaiian music in the
background. Pete Etnoyer is especially
interested in the hulas. Pete is our Californian
coral/mapping guy, and is trying to work
out whether the hulas are an extension
of the coral (a so-called sweeper tentacle)
or in fact a separate animal that has
attached itself to the coral.
The five or six hours after Alvin surfaces
are usually the busiest time for the science
group. Delicate animals need to be immediately
transported to the cold room, where bundled-up
scientists identify them and divide them
up for different kinds of analysis. Rocks
collected from the edge of undersea escarpments
are sliced and diced to reveal their geological
secrets. Water is filtered through meshes
of different size to catch successively
smaller and smaller creatures. The video
tapes recorded during the dive must be
duplicated for the science group, and
everybody's collection data has to be
gathered into one place. Dinner often
is forgotten as someone glimpses something
particularly spectacular. My proudest
contribution yesterday was quite serendipitous.
I was hanging out in the Alvin lab, waiting
for a bucket of purified water to fill,
and idly looking at small pieces of coral
in glass petri dishes. On one of them
I spied a very pale, half-inch long crabby-looking
thing. "Hey," I announced, "there's
a small crabby-looking thing here"
(that's about the limit of my vocabulary
for anything macrobiological.) Expert
evaluation revealed that it was in fact
a pycnogonid or "sea spider".
These crab-imitators grow up to 2 feet
long, feed by sucking the juices out of
jellfish etc., have no anus, and the males
brood the eggs. Who knew?
Several people have asked what I am actually
doing out here. Well, besides expertly
identifying crabby-looking things and
the different flavors of Jelly Belly beans
kept up in the mess, I am studying bacterial
communities. For those of you not yet
in the know, bacteria make the world go
round. The ones that give you plague,
cholera, and all those other nasty diseases
are in fact a tiny minority of the bacterial
world. The rest of them are busy keeping
us alive - generating our atmosphere,
recycling carbon, nitrogen, and sulfur,
breaking down dead stuff. There is more
microbial biomass (living stuff) on the
earth than biomass of all other lifeforms.
And what we have found out in the last
ten or so years is that our tried and
trusted methods for studying these beasties
(growing them on agar plates and in tubes
full of yeasty broths) has been a spectacular
failure. New methods, that by-pass the
cultivation step and identify bugs based
on their DNA sequences, have revealed
that cultivation gives us 0.1-1% of all
the bacteria that are out there. The rest
of them are picky eaters - just not particularly
keen on what we are feeding them there
in the lab, and so they don't grow on
the agar plates.
So we are applying this DNA-sequencing
approach to study the bacterial communities
associated with deep-sea corals. Like
me before I got involved in this stuff,
you probably have always associated corals
with tropical climes, shallow water, and
the like. But there are cold-water corals
that inhabit deep, deep waters (down to
3,000m). Because of their relative inaccessibilty,
these corals have not been as well-studied
as their shallow-water cousins, and so
there is much to be learned about their
distribution, reproduction, and relationships
with other creatures in the deep-sea environment.
Some of these relationships, we think,
hinge on the thick mucus produced by the
corals. The mucus is thought to have a
mostly protective function, guarding the
coral against threats such as drying out
(more a problem in tidal shallow-water
habitats) and colonization by other creatures.
But the mucus also provides an ideal home
for teeming bacteria, which in the better-understood
shallow-water corals can be there in thousands
per drop of mucus. Coral mucus is released
from the coral, drifts through the water
column picking up other particles, and
eventually falls down to the sediment,
where it is snapped up by detritus feeders.
So the mucus and its associated microbes
are an important part of the food web.
From our 2002 cruise, we know that the
mucus contains microbes, and there is
a hint that different coral species harbor
specific microbial populations. We hope
to gain many more samples on this cruise,
to help answer all our questions about
this system: Do different coral species
really attract different microbes? why?
and how? Do the animals we see perched
on the corals feed on the mucus + microbes?
Why does one coral host lots of animals,
while a neighboring seemingly-identical
coral is bare? Could it have something
to do with the mucus and its microbes?
So we are armed with collection tubes,
microscope, and DNA extraction kits to
try to get some answers. Many of the answers
will come months later, when all the data
are analyzed.
Well, I wanted to write about the first
dive of my friend Catalina, which is occurring
today. But I think I may be approaching
my email limit, so it will have to wait
til next time. Right now I am going to
head up to Top Lab, where we are due to
receive a phone call from a middle school
in Rhode Island. We will be on hand to
answer science questions from the students,
and we will also be able to patch them
through to Alvin so they can talk to the
pilot and observers. Ah, the wonders of
technology.
More later,
N.
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