 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Life Aboard Ship, Dispatches From South of the "Roaring Forties"
|
Sunday, June 20, 2004
Well, we're on our way to Bouvet (or Bouvetoya, depending I guess, on whether you are Norwegian). It’s a small island that belongs to Norway. We left Bristol Island this morning before breakfast and came out of the ice around 3 this afternoon. We decided not to try to go further south for several reasons. First, this is becoming an early and hard winter down here; from the satellite ice cover data we get every few days, we can see a steady increase in ice cover extending north around the islands. [Note: go to http://www.icefish.neu.edu/currentactivities/ to look at an ice map.]
Second, going through the ice is slow, and although
we have a great deal of flexibility in how we use our DAS (days at sea),
we have NO flexibility about
our arrival in Capetown. It has to be July 17th. Third, breaking ice uses
much more fuel than running in the open sea, especially if we use all the mains
(the PALMER has four main engines, for more information about the ship, go
to http://www.icefish.neu.edu/onboard/abouttheship/). Our normal cruising
at
10 knots uses only two, which saves fuel. So, off we go.
The PALMER left the uninhabited South Sandwich Island of Candlemas and is heading toward a Norwegian island called Bouvet, or sometimes Bouvetoya, farther east.
I was sorry to leave the ice. I loved it, cold as it was (a few nights ago it got down to around -18°C (with a wind chill of about -40°C). The light was always changing and the landscape with it; I took hundreds of photos (maybe thousands by now) and could have taken more. For instance, old ice is blue, sometimes like a robin's egg (it's blue because when it's fresh it includes lots of tiny trapped air bubbles, but as it ages and compresses, the air is forced out). It can show the layers forming it, so you get this beautiful striation like sandstone or the walls of the Grand Canyon. We all agree it really is awesome (in the real sense of the word) to see these islands, the bergs, sea ice, and the animals that live here, and we are fortunate to be able to work on them.
The
NBP has a heated working deck. When it's cold enough to freeze water
on the deck, the engineers fire up boilers that heat glycol which is
then circulated
through channels under the deck, raising the temperature to about 100°F.
It's a really wonderful sight to see everything above the deck covered in
ice, and yet have steam rising off the deck from evaporation!
This picture was taken a while ago. When we left South Georgia Island, two-thirds of the population came to see us off. In the background is the King Edward Point laboratory of the British Antarctic Survey.
At the cruise planning meeting last October in Denver, when I asked Herb Baker, our on-board Marine Projects Coordinator, how warm the deck is, he told me that you can lie down on it to warm up when you get cold. That was hard to believe, but it IS true. Although I wouldn't recommend that; if you're outside, you're working; otherwise, it's better to be inside anyway.
The scientists concerned, Stacy Kim, an Adjunct Professor at Moss Landing Marine Laboratories in Moss Landing, California, and Andrew Thurber, her graduate student, are funded by the National Science Foundation to study the communities of bottom animals both in McMurdo Sound, Antarctica, and at the sites visited by this cruise. They are sampling using the SMG to get bottom infauna (animals that live in the bottom) and the trawls to get the invertebrates that live on the bottom. They put the sediment from the grab through a 500-micron (half millimeter) sieve and save all the animals that don't go through the sieve. Because the trawls catch far too many invertebrates to keep, they take a subsample (a known proportion of the total catch, selected randomly to prevent bias, and analyzed as a representative of the whole catch). The samples are preserved, and will be analyzed back in California, where Stacy and Andrew will identify everything possible (there may be new species collected) and then analyze the structure of the animal communities at each location and compare them to one another and to those in other areas, such as McMurdo.
We don't know much about the bottom fauna of these islands. The infauna of
Bouvetoya is unknown except for some very old samples taken without benefit
of modern technology. At Tristan da Cunha, the next island group we will
visit, there is a little more known, but still not much. It's a measure of
how tedious
and difficult this work is that Stacy and Andrew won't know for months, and
possibly years in some cases, whether there are any new species in the infauna.
The color of this iceberg shows that it's an old one. As air in the ice escapes with time, the color changes from white to blue.
You may wonder why this kind of work is important. Stacy and Andrew are community ecologists, trying to understand the interactions between the individual organisms and species that make up a community. Although it's hard to understand why a sponge (for example) is important to us directly, the indirect linkages are important. The sponge provides habitat and hiding places for amphipods that are food for fishes that we eat. Sponges may also provide protection: they have sharp glass spines and toxic chemical compounds, providing safe places for fishes to lay eggs, and their structure (some are more than a meter tall) can shelter fish and other animals from predators such as seals. No animal (including us) survives in isolation.
Now we are looking for
a place to make a deep tow (more than 4000 m or 13,000 ft. deep). We have
adjusted our course
to Bouvetoya so that it passes across
some likely places where the isobaths are very far apart (hundreds of miles)
indicating that they may be flat. Unfortunately, the best bottom chart we
have shows these depths in 500 m (1625 ft.) increments, which means that they
can
be very rough as long as the relief is less than that. We need a flat spot
of at least 15 miles to safely avoid hanging the net up on a rock. I think
that the farther we get from the South Sandwiches, the more likely it becomes
that we will find one. We will surely find out in the next couple of days!
In the meantime, we are all catching up on sleep, work, "housecleaning",
and other tasks that are hard to accomplish when we are all working as many
hours a day as we can.
This photo shows the steam, and also shows several scientists getting ready to put a Smith-McIntyre Grab (an SMG) over the side in about 500 meters (1625 ft.) of water last night (isn't technology wonderful?). The grab takes a sort of clamshell sample of the bottom sediments and the animals that live in them.
BoatUS : my.BoatUS : Membership : Boat Insurance : Towing Services : Boat Loans
Online Store : Boat Graphics : Classifieds : Site Map : Contact Us
©2008, Boat Owners Association of The United States. All Rights Reserved.
