Life Aboard Ship #19 July 14, 2004 #18 July 11, 2004 #17 July 6, 2004 #16 July 5, 2004 #15 June 30, 2004 #14 June 27, 2004 #13 June 23, 2004 Bouvet Island #12 June 20, 2004 #10 June 16-17, 2004 South Sandwich Islands #9 June 13, 2004 #8 June 9-10, 2004 #7 June 4-6, 2004 #4 May 26, 2004 #3 May 23, 2004 #2 May 19, 2004 #1 May 16, 2004 Punta Arenas, Chile May 14, 2004 Landfall: Visiting Islands in the Atlantic Ocean June 16, 2004 South Sandwich Islands May 30, 2004 Falkland Islands May 26, 2004 Science on the NATHANIEL B. PALMER June 24-26, 2004 June 15, 2004 May 30, 2004 Questions & Answers

Monday, May 31, 2004
Well, we searched and searched for Champsocephalus esox, but it seems nowhere to be found. We have fished all the places around the Falklands where it has been previously known, but only caught hundreds of thousands of munid crabs (they look sort of like crayfish, see http://www.icefish.neu.edu/currentactivities/) and a few other nototheniid fishes.

The reason why C. esox is so badly wanted by the scientists on the ICEFISH cruise is that it is the northernmost representative of a family that has no hemoglobin in its blood. That is, they are white blooded. Perhaps it is needless to say, but this is the only vertebrate without hemoglobin in its blood, a very unusual situation. All the other vertebrates (and many invertebrates, too) have some compound in the blood that has an affinity for oxygen and makes the blood able to carry more of it to the body tissues.

It was thought for a long time that they had no red blood cells at all, but not too long ago it was found that they do in fact have such cells, but they are 1) clear, and 2) not abundant, and are therefore hard to both see and find. We need C. esox to see if it, as the northernmost representative of its family, has any different genes and physiology from its more southern (colder climate) relatives. There are 16 species in the family, and all the rest of them live further south. By looking at this species, we can estimate the time for its evolution (since they split off from their nearest relative) and how (or if) their physiology has changed in this relatively short period of time. In addition this is probably the most remote area of the Antarctic, in the sense that few expeditions study this area and it is very hard to get here.

Tuesday morning, June 1, 2004

Photo #1: One of three icefish (Champsocephalus esox) caught and being kept alive in a tank aboard the NATHANIEL B. PALMER. Scientists are studying how the fish swim.

We lucked out - caught three C. esox (see photo #1). One has been sacrificed already for tissues, but the other two are alive and well. This one is being used for swimming studies and is being photographed and videoed from the side and above. The grid you can see is to show its position better. We also retrieved our fish traps but did not have much luck with them - we caught one moderately small toothfish. So, we are now on our way to Shag Rocks (so named because they are the nesting place for the “blue-eyed shag”, a cormorant).

Photo #2 of C. esox shows some of the internal organs. Every one is white! The large creamy white organ being held is the liver, and the tweezers are next to the stomach (which was quite full of the last meal, another fish). You can’t see the gills, spleen, pancreas and gonads, but they are also white as is the flesh. It gives you a striking idea of how what we take to be “normal” appearance of flesh and internal organs is the result of coloration by hemoglobin. The blood is also white, and (compared to other fishes) there is a larger than usual volume of it - probably because the fish needs that extra volume to make up for its lower ability to transport oxygen. When it clots, it looks like cream.

Why this unique character evolved is problematic. It was probably a mutation that would have been fatal in any other environment but the extreme cold of the Antarctic. Because of the cold, seawater is saturated with oxygen (that is, there is as much as it will hold) at a higher concentration than is possible in warmer waters. This in turn makes it possible for icefish blood to carry enough oxygen for the fish to survive. Warmer waters will not hold as much oxygen and therefore tissues could not get enough of it without hemoglobin (or hemocyanin, the pigment that makes crustaceans “blue-blooded”). Antarctic fishes in general are inactive and slow-moving, possibly for several reasons, one of which could be their relatively low metabolic rate owing to the extremely low temperatures at which they live. A low metabolic rate means lower demand for oxygen and thus the possibility of surviving without hemoglobin.

Wednesday, June 2, 2004

Photo #2: C. esox is an unusual fish because it doesn't have red blood, hence the unusual appearance of its flesh and internal organs.

Now it’s my turn to collect, so I have selected three stations for deep trawling: one at 2250 m (7310 ft.), one at 3000 m (9750 ft.) and one at 4500 m (14625 ft.) depth. We will arrive at the first (shallowest) one at about 2100 today. When we come on station, the first thing we do is survey the bottom using our multibeam sonar system, an extremely accurate computerized echo sounder that uses a number of different sound frequencies to see and characterize the bottom. For instance, not only can we see whether it’s flat, but we can also determine fairly accurately what it’s made of (sediment, rock, sand, etc) and even what’s below the surface (sediment covered rock, for instance). However, the system does have its limits, and (as we saw on Burdwood Bank) it may look flat, but be rough enough to chew up our gear very effectively. So it’s always a risk; an old oceanographer’s saying is “if you can’t afford to lose it, don’t put it over the side”. If the bottom looks flat enough, we will tow. Otherwise we will keep looking until we run out of the allotted time and have to move to our next station. We don’t expect any problems finding places to tow, however, because we have selected areas that are known to be relatively flat and sediment covered. These tows will take a long time to make using our 30-foot otter trawl. The deepest one will take about 12 hours start to finish.

We don’t specifically know what to expect either in terms of catch size or composition. Generally, we know what fish families occur at these depths here, and that catches will be small. There has been relatively little sampling of great depths in this region, and it’s entirely possible (likely, even) that these stations have never been sampled. This is the first thing I like about deep-sea sampling: it’s like a birthday, Christmas, Hanukah, and all other gift-receiving holidays all rolled into one! Every organism is like a wonderful gift, and it is not uncommon for some of them to be collected for the first time. Imagine being the first person to see an animal no one’s ever seen before.