23 October 2003

Jonna here:

Today at McMurdo Station the sun will set at 12.26AM for the last time. From here on out we will have 24 hours of daylight until February 19, 2004 when the sun will again dip below the horizon. Being in a place with 24 hours of daylight is an amazing experience. You walk out of a building at 10:00 PM and it feels like 3:00 in the afternoon. I find that I have much more energy with all this light and I tend to sleep one or two fewer hours a night.

Sunset at McMurdo

It is no wonder that this continent is the only one on earth that humans have never inhabited. As we approach austral summer, today's maximum temperature was 16 deg F/-9 deg C, minimum temperature was -1 deg F/-18 deg C, peak winds were 24 knots and minimum wind chill was -42 deg F/-41 deg C. Antarctica is a harsh and unforgiving place in terms of weather conditions.

Our morning began with Stacy and Rob doing hard-hat dives at the outfall. They were collecting core samples and syringing up beggiotoa (a type of bacteria that thrives at the sewage outfall) for experiments at Outfall A and Cinder Cones. The beggiotoa was used to innoculate artificial enrichment material (a concoction of carrots, beans, peas, rice and flour meant to mimic human waste) in Tupperware containers under cages at Cinder Cones. This was done in the afternoon by Stacy, Jennifer, and Jim. In the next few days, uncaged Tupperware containers containing the same artificial enrichment will be placed in the experimental grid. The main objective of this experiment is to find out if the presence of beggiotoa is excluding Odontaster sea stars from accessing and thus feeding on the enrichment pile at the sewage outfall.

Meanwhile Craig and I headed to our S4 current meter and CTD station, which is located on the sea ice about 27 km from McMurdo Station, to deploy the CTD. The visibility on the way out was limited but to our surprise we were able to distinguish the Erebus Ice Tongue for the first time although we had passed it many times in the previous days. We were really surprised to find out how close to the flagged road the tongue was. There are several large sea ice cracks in the vicinity caused by the pressure of the ice tongue.

	Large sea ice crack in foreground and Erebus Ice Tongue in the background

Craig at winch controls.	CTD cast.

On the way home the visibility was much better and we had some great views of Inaccessible, Tent, Big Razorback and Little Razorback Islands and Turks Head point.

	Tent Island in foreground, Big Razorback Island in the middle, and Turks Head and Mt. Erebus in the background

After a Mexican fajita lunch I went for my fourth dive here in Antarctica, my third dive at the jetty. I am an invertebrate zoologist so I want to tell you about a few of the really amazing invertebrates that live here in Antarctica. Sponges or Porifera (the scientific name for sponges) are the most abundant marine invertebrate in Antarctica. Sponges in Antarctic marine communities are similar to corals in coral reef habitats in that they provide much of the benthic structural relief, a place to hide, and a food source. For our research we regularly collect bush sponges, Homaxinella balfourensis, and pipe sponges Haliclona sp. Two of my favorite species are the knob sponge, Inflatella belli, and the spiky sponge, Cinachyra antarctica. Sponges in Antarctica can get amazingly big. Some barrel sponges are big enough for a person to sit inside.

Knob sponge.	Barrel sponge at the Jetty.

A really cool animal that we frequently see are sea spiders or pycnogonids. A phenomena that we observe in Antarctic marine communities is gigantism/dwarfism--that is organisms that are normally quite small attain larger sizes or conversely, organisms that might normally be big are quite small. Pycnogonids in most habitats are quite small but here in Antarctica they can be as big as a dinner plate. This can be a response to insular environments where resources can be limited and/or there is a release from predation.

One of my favorite animals that we frequently see at our dive sites is the soft coral, Alcyonium antarcticum. Corals are colonial animals in the phylum Cnidaria which includes sea anemones, hydroids, and jellyfish in addition to soft and hard corals. The little white plumes covering the animal are individual feeding polyps. Soft corals are permanently attached to hard substrate and feed by extending their polyps and filtering plankton from the water column.

I will continue sharing the wonderful Antarctic marine community invertebrate life that we see when we dive in my next journal entry.

Pycnogonid	Alcyonium antarcticum