Today's update is provided by Amanda Bates, a Ph.D. student from the University of Victoria.
Site: 21°N – Clam Acres
was an exciting day for many of the scientists on board because we
launched the first dive of this expedition on the East Pacific Rise. The
control room seats were full when we reached the seafloor, which was
sparkling basalt. It is fun to think that we were looking at the newest
part of our planet. The clean basalt was also a nice visual change from
the mud bottom that we were exploring at Guaymas. We started the dive in
search of Clam Acres, which is the rumored home of giant clams (Calyptogena
magnifica) up to one foot long (see above). Although all eyes in the
control room were keen to find serpulid worms and galatheid crabs, which
are species that live just outside
vents and indicate that a vent is near, we were distracted by other
interesting deep-sea species along the way. For example, we found a unique
type of sponge that grows from a stalk and is shaped like a mushroom (see
left). After three hours of exploration, we found Clam Acres, a diverse
site with abundant clams and tubeworm (Riftia) bushes.
Many vent animals such as snails, crabs,
and fish use tubeworm bushes as habitat. Can you find the zoarcid fish
peeking out from the base of the tubeworm bush? We are interested in
describing how the number of species found on tubeworm bushes varies with
the size of the bush.
species found on the East Pacific Rise are well described. Therefore,
species can be identified from photographs. Luckily we have a
high-resolution camera on the ROV, which we used to create close-up
mosaics of the tubeworm bushes (see left). Although many species are
missed using this technique because they are too small or occur inside of
the bush, photography has many advantages. Taking photo mosaics is not as
time consuming as taking a tubeworm grab. Therefore, more bushes can be
examined in the precious bottom time we have in the vent habitat. Also,
taking images is less invasive than removing many tubeworm grabs. This is
the first time we have used photo mosaics to identify animals on
tubeworms, and we are currently downloading the images from the camera. If
we like the results, we plan to use this technique in the next two dives.
Wish us luck!