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.
Our
first challenge is to identify the associated species that use tubeworm
bushes as habitat. One method is to collect the tubeworm bush, bring it to
the surface, and preserve all the animals on the tubeworms. The animals
can then be examined with microscopes and photographed. Grabbing a
tubeworm bush by the base and putting it in a secure box for transport to
the surface may sound like a straightforward task. However, tubeworm
bushes can be a struggle! It is difficult for the submersible
pilots to find a spot where they can land and grab the bush securely
at its base when the lava is as bumpy as it was today (see right). Only
small tubeworm bushes can fit in the boxes on the submersible. Also, the
worms often grow together and tangle and can be difficult to tease apart
or remove from rock crevices. Faced with these challenges, we decided to
be creative.
The
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!
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