Friday, Nov 7 2003

Dan writing.

Another busy day of diving in New Harbor. The day started off with Stacy and Craig going in again at our experimental site in Explorer’s Cove. Stacy collected a set of cores while Craig took photographs and collected animals. After lunch Stacy went in yet again, but this time with Jonna at Cape Bernacchi which is our other experimental site out here in New Harbor. This was the first dive at this site for the year, and since we were using a hole blasted at GPS coordinates recorded last year, it was a little bit of a guessing game as to just where the experiments would be in relation to the hole. On top of this it was extremely dark under the ice because of drifted snow an additional year’s worth of ice growth. As a result, Stacy and Jonna spent about 20 minutes swimming around in the dark with their flashlights before they located their target. In spite of this it turned out to be a successful dive and we had more samples to take back to the lab for sorting.

Stacy and Craig preparing to dive at Explorer's Cove

Late in the evening Jennifer and I got a chance to go in at a site we are calling the Circus. This is the location where John Oliver and Paul Dayton, our predecessors in this work, set up a large number of experiments during trips here between 1971 and 1974. John Oliver came here with us last year and he re-located this site, after not seeing it for nearly 25 years, on a far ranging swim from another dive hole. It was quite a pleasant surprise not only to find this array of floating lines, cages and racks suspended off the bottom still somewhat intact, but to discover the number and size of animals which had taken advantage of these structures as hard substrates on which to grow. On this side of McMurdo Sound there are far fewer sponges and soft corals because hard substrate is relatively rare - the bottoms are mostly made up of fine glacial silt which has been pushed down out of the Trans-Antarctic Mountains. This doesn’t mean that conditions are not suited to the growth of these animals, because many of the sponges growing on experimental structures at the Circus are amazingly large given the relatively short (in Antarctic terms) 25 years they have been alive. One species, Scolymastra joubini has been recorded as only growing millimeters in a decade, but there are individuals over 80 cm tall growing on artificial substrates at the Circus. Many of these sponges are covered in beautiful crinoids or feather stars and fish and seastars seem to like hanging out on them as well.

Crinoid atop a large Scolymastra sponge at the Circus