22 November 2003
Jonna's journal day:
Our research is winding down and this is my last Saturday in
Antarctica. Jim captured the essence of my feelings in his last
journal entry (Monday 11/17) where he writes about the magnificence of
Antarctica and how this continent has a way of putting things in
perspective and re-igniting psych and stoke in one's life. I know all
of us feel very privileged to have spent time here. Experiencing this
incredible landscape has definitely been one of my life's highlights.
I have found that Antarctica dwarfs most sights I have ever seen and
expletives are required in any attempt to capture its grandeur. I
think our web site photos have given you a taste of how large, stark,
lovely, and awe-inspiring this place is. I hope we have sparked your
interest in science and in polar environments and passed along a sense
of responsibility and stewardship; a sense that we must work hard to
take care of our planet to preserve natural wonders like
Antarctica.
This morning while Stacy went diving at the outfall using surface
supply to recover the time lapse camera, Dan worked on the time lapse
movie, Jenn and Craig deployed the CTD and recovered the S4, and I
worked on my sea squirt project.
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| Stacy in Viking dry suit for surface supply diving |
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| Craig at his computer downloading S4 data - or trying to
at least |
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These last couple weeks I have spent time working on a project that
Kathy Conlan and I began in 1996. We are studying the natural history
and feeding behavior of the sea squirt or tunicate, Cnemidocarpa
verrucosa. Another component of our work involves the examination of
a C. verrucosa population in the proximity of the sewage outfall
compared to a population outside the influence of the sewage outfall:
we are comparing size frequency and diet between the two
populations.
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work station where I examine the stomach contents of
C. verrucosa using a dissecting scope |
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Cnemidocarpa verrucosa is found throughout Antarctica and the
Antarctic Peninsula, South Shetland Islands, South Orkney Islands,
South Sandwich Islands, South Georgia Island, Kerguelen Island, Bouvet
Island, Crozet Island, Falkland Islands, and Tierra del Fuego from 5
to 761+ meters depth. C. verrucosa is the largest and most
abundant of the Styelidae (solitary) tunicates, attaining lengths of
25 to 30 cm. The body shape of C. verrucosa may be
cylindrical, ovate, or barrel shaped and has been described as
football-like. C. verrucosa has a thin, tough, flexible,
opaque body covering (test) whose surface may be smooth or roughened
by furrows, wrinkles, and conical or low wart-like papillae. The test
is an acellular covering secreted by the epidermis; it is largely made
of tunicin, a substance allied to plant cellulose and the only
cellulose-like substance to occur in the animal kingdom.
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| Cnemidocarpa verrucosa - two adults |
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| Cnemidocarpa verrucosa - Adult and
juvenile |
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Cnemidocarpa verrucosa lives at least four years. Only one
study has looked at the diet of these tunicates and they were found to
consume diatoms, nanoplankton, bacteria, and detritus (we are further
examining the diet and feeding behavior of C. verrucosa).
The bright yellow lamellarian mollusc Marseniopsis mollis is
the primary predator of C. verrucosa; no seastars or fish
have been observed eating C. verrucosa. M. mollis
is protected from predation by a chemical, homarine, which deters
feeding. It obtains its defensive chemical homarine from bryozoans
and hydroids growing on the surface of C. verrucosa.
In the afternoon all of us went to Cinder Cones to deploy the time
lapse camera, to look for sea squirts, and to collect one urchin (a
job for professionals only!). The drive out to Cinder Cones was
beautiful as usual. I thought that the view of Mt. Erebus looked
especially surreal, almost like it was a fake back-drop for a movie
set.
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| Mt. Erebus |
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The dive was quite easy for Craig and I so we had a lot of time to
explore - we spent a lot of time in the shallows checking out the
shapely and beautiful ice chandeliers or brine tubes. Stacy and Jenn
had a busy work dive setting up an experiment and arranging the time
lapse camera to film the experiment.
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| Dan with the time lapse |
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| Time lapse camera going down the hole |
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We ended the day with a big celebration at the Dive Locker. We were
celebrating the winding down of a very successful research season for
ASPIRE and saying our "good-byes" to many of the people who have made
the success of our research possible. One thing for sure, success
here in Antarctica is a team effort and the support at McMurdo is
absolutely fabulous. I am very grateful and proud to have been a part
of the ASPIRE 2003 team. It has been a great, eventful, fun-filled,
and action packed season. Thank you Stacy!
