Posted by graduate
Sipe, University of Delaware College of Marine Studies.
The last couple of dives have led to interesting findings.
The biologists are very excited about the possibility that
they may have discovered a previously undescribed symbiosis.
A red polychaete worm about 5 to 6 centimeters in length
was collected from the vents. Tim
Shank identified that the species belongs to the family
Polynoidae. He and Craig
Cary were intrigued by the great number of large white
setae on the worm. Setae are hair-like structures
that line the length of the worms body and are used
for slivering through the muddy bottom.
the thought crossed Craigs mind that the prominent
setae may actually be covered in bacteria. There are quite
a few symbioses between hydrothermal vent worms and bacteria,
so it would not be surprising to find such an association.
Craig snipped off a few setae,
stained them with a fluorescent dye, and viewed them under
the microscope. Based on his initial crude assessment, he
thinks the cells may actually be bacteria. He plans on looking
at the structures more closely when he returns to the University
of Delaware and uses his special microscopes. This was a
very unusual specimen in their collection, for it was the
only one sampled so far during the cruise. Hopefully, they
will be lucky enough to find another.
As I have alluded to
before, the science party has been frustrated with the sediment
cores they have collected. George
Luthers laboratory, including post-doctoral fellow
Rozan, will use electrochemical techniques to characterize
the chemical environment of the sediments. They insert their
special sensor probes vertically through the sediment layers
and measure the chemistry at different depths of the core.
As is usually the case with sediments, there are distinct
zones or layers that have different chemical compositions;
therefore, it is important that the layers be preserved
while remaining in the cylindrical sampler.
There have been many
interesting methane-producing bacteria in these sediments,
which the microbiologists are thrilled about. However, these
methanogens produce gases that bubble within the core and
disrupt the sediment layers. To solve this gassy problem,
the scientists planned to sample less methane-rich sediments
this strategy was a success because the cores they
collected remained undisturbed throughout the dive.
The scientists are working with the cores this evening.
Much to the dismay of the rest of the ship, the sediment
cores are super-stinky! They contain high levels of hydrocarbons
(diesel fuel) and sulfides, both of which have smelly odors.
The hydrocarbon stench overwhelms the sulfide odor, although
Tim comments that the talented nose is able to discern both
smells. I am not sure Id care to learn that skill.
Ortmann is excited with the results of her marine virus
experiments. Viruses get a bad rap, because we usually associate
the word virus with nasties that harm humans.
But viruses are everywhere in our world most of them
dont even bother humans at all. The oceans are teeming
with marine viruses that play an important part in the marine
ecosystem. Surprisingly, no one has reported on whether
there are viruses living at the hydrothermal vents. Are
there viruses? How many? Where are they? Do they like the
super-hot vent fluids, or do they prefer to hang out in
the cold water?
It turns out that Alice has found many viruses in her water
samples taken near the vents. She still needs to analyze
her data by plotting graphs on the computer and correlating
these numbers to the sampling areas and temperatures. No
doubt, she will be glued to the computer screen doing her
analyses during our transit to the mainland. It will be
interesting to see the story she tells based on her results.
Two brilliant pink spiny spider crabs have been collected
from the vents during the cruise. These crabs measure about
a foot-and-a-half across when their legs are extended. There
are thousands in the Guaymas Basin vents, but they are challenging
One of the crabs was a gravid female, meaning that she was
toting hundreds of eggs in her carapace. The eggs look like
a palm-full of blackberries, but were connected to a stalk
such as grapes are. The vent biologists took a couple of
samples of the crabs leg tissue, which will allow
them to examine the DNA for systematic examinations (species
identification) and determine what foods they are eating
using special isotopic experiments. Craig Cary and Tim Shank
have arranged to donate the male crab to the Smithsonian
Institution when they return to the States because they
believe that the museum does not have a good specimen of
this crab species.
Tomorrow is the final Alvin dive of the Extreme 2000
cruise. Post-doctoral researcher Dorothee
Gotz and marine chemist Don
Nuzzio will be diving in the sub with pilot Blee Williams.
The scientists and Alvin pilots have grown increasingly
familiar with the Guaymas Basin vent terrain and can quickly
maneuver from site to site. The submarine dive will be moved
ahead one hour earlier tomorrow, because as soon as the
sub surfaces at the end of the day, the R/V Atlantis
will start cruising for the mainland and the port stop in
Manzanillo. The sky will still be dark and speckled with
stars when the sub goes in the water a most spectacular