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7 May, 2000

Ice and Going to Chile Question 78: More than 20,000 fish species exist in the world today, about 58% of them inhabiting marine environments. There are more kinds of fish than all other kinds of vertebrates put together. Since the Southern Ocean has about 10% of the world's ocean surface, how many fish species do you think live south of the Antarctic convergence? Waking up in my cabin was a surprise this morning. It isn't the same room I have been living in for the past two months! I have the lower bunk in our cabin and can pull the curtain across to feel like I am in a warm, dark litttle cocoon. Katrin and I had to rouse ourselves for the mandatory safety meeting at 10 am but otherwise we were so exhausted that sleeping, reading and snacking in bed sounded like the best activities in the world. The extra blankets we found in the laundry room help with the cocoon illusion as the ship is fairly chilly otherwise. The safety meeting was the same as when we came south on the Gould in March--try on life vests and survival suits in the lounge, then stow those back in our cabins before heading outside to practice climbing into the lifeboats. The last part was certainly more exciting than the first time! Even though the water we are travelling through now is relatively protected, the ship is still moving and all the decks and hand rails have ice and snow built up on them. There is no shame in sliding your feet carefully along the edge of the deck and never letting go of the rails. This drill felt much more real than when we did it in the sun at anchor off Punta Arenas, especially when we had to climb the stairs and step across the gap to the boat with nothing but moving icy water underneath. I was very glad to get back to my warm bed! At this time of year, winter is beginning and sea ice is in the process of forming. Sea ice that has already formed fits roughly into three main categories: fast ice, open pack ice, and close pack ice. Fast ice is sea ice which remains fast (meaning attached, not quick) along the coast, where it is attached to the shore. Open pack ice is sea ice composed of floes seldom in contact and with leads of open water between them. Close pack ice is composed of floes mostly in contact with one another. As the ice begins to form it moves through stages of development, starting with new ice (a general term for recently-formed floating ice which includes frazil ice, grease ice, slush, shuga, ice rind, nilas, and pancake ice), and progressing to young ice (floating gray or gray-white ice 10-30 cm thick in the transition stage from new ice to first year ice, its snow cover mostly moist and slushy), first year ice (ice that is 30-70 cm thick and between a year and two years old), and old ice (floating ice more than two years old and 3 meters or more thick. At the bow of the Gould we are cutting through new and young ice now. Over the last month we have been watching new ice form on the water around Palmer and in our outdoor aquarium tanks. The tanks hold salt water, and even though they have covers, they get colder faster than the ocean water because of their smaller volume. Frazil ice is the first stage to start solidifying. When it is at its peak the whole surface of the water is thick with a layer of fine spicules (spikes) or plates of ice that aren't connected and is called grease ice. The thick layer of tiny pieces make the clear surface of the water look cloudy, soft and unfocused because it reflects very little light. Then the ice can either form an elastic crust or a brittle crust, depending on the movement of the water it forms on. Ice rind is formed on a quiet water surface and is a brittle and very shiny crust, while nilas is a matte, elastic crust that bends easily on waves and under pressure. These can be up to 10 cm thick. Some of the stages of new ice formation that we didn't see in our aquarium tanks were slush and shuga. Once it snows on top of any wet ice you get slush--snow saturated and mixed with water. This can form on any age ice just as long as the snow doesn't fall on open water and melt. Shuga is an accumulation of spongy white ice lumps only a few centimeters across formed from grease ice or slush. Answer 77: Squid are fast swimmers and carnivorous. They eat a variety of things, including other squid, amphipods, krill and fishes. They can chop prey into small pieces with their beaks.


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