July 22, 2008
We awoke to cheerful signs, adorned with Hawaiian leis, welcoming "hump day" (the half way point of our cruise) taped to our cabin doors, but hump day did not go as planned. I was expecting to be on a transit this morning but instead we were still at Station E. Apparently water leaked into the strobe light of the Yoyo camera during last night's deployment and the scheduled Blake trawl never happened. A smooth Blake trawl requires a pretty gentle bottom profile and the ship had a difficult time locating a flat stretch of seafloor to drag the net. So the day crew jumped right into a Blake trawl at the start of our shift, which is a bittersweet way to start off the day. A fair amount of sorting through mud in return for observing a plethora of interesting creatures. We turned up another octopus and a good sample of sea urchins in addition to the usual bizarre assortment of invertebrates in all shapes and sizes.
There was a little sea swell rising up enough to gently wash over the deck from time to time to remind us it is winter in the southern ocean. The rolling of the ship has been increasing in gentle increments allowing most folks to adjust well to be outing of the ice.
I am sure lots of people would nominate emptying the mud out of a Box Core for some reality show in line with "world's dirtiest jobs," but from here the Box Core is looking good-tonight I was trained in dissection which is now on my list of tough jobs to do at sea. Linda showed me how to dissect Peniagone specimens as she worked on sea urchins. With a background in biology I have done my share of dissections, but the cold room with poor lighting, bundled up layers on a moving ship takes the activity to another level.
After each bottom trawl, we set aside a substantial sample size of about 10 different species of invertebrates for dissection to prepare tissue and ingested sediment for further analysis (20 animals of each species from each station is the target). Mostly we dissect sea urchins, holothurians (sea cucumbers), and echiurans (a type of worm). All of these organisms were studied back on the FOODBANCS1 project and are selected for being the more common deposit feeders in the benthic zone of the Antarctica Peninsula. The digestive tracks are isolated to assess, through chemical analysis, the age of the materials in the animal's gut. By doing chromatography on the sediment in the fore-gut we can quantify the amount of chlorophyll-A to see how much fresh food the organism has taken in. We can also look at the type of foods they are selecting and the nutritional quality of the algae. The University of Hawaii team uses an elemental analyzer to approximate the protein to lipid ratio in the gut to assess the energy content of deposit feeder tissue. Liz Galley is looking at seasonal and latitudinal changes of gonad mass as an indictor of food richness and availability. All dissected samples are frozen at -80° C for the trip back to the States.
When it was first explained what I was to dissect, I thought I was being hazed. It took me a moment to figure out that they were serious. I worked on a small animal around three inches in length. My job was to cut open its jelly like body and remove, without tearing, an intact digestive tube from beginning to end. As the ship rolled my specimen slid across the tray and I followed along with forceps and a scalpel. The scalpel I realized was useless on fresh tissue so I turned to small scissors, although it was difficult to get my gloved fingers to grip them. The digestive tube is about 10 - 12 centimeters in length and about 3 millimeters wide and has invisible connective tissue holding it in place. I was very proud when I finally freed the tube from the body, but then learned I was not done. I was to find the "fore-gut" and separate the top portion of the digestive tract so I could remove the ingested sediment. This entailed holding one end of the tube and using small forceps to gently squeeze out the contents into a specimen bag, like a tiny fragile toothpaste tube of mud. It was not an easy task but not the most difficult dissection they do here at sea. I was amazed at the number of hours folks put in on dissection in addition to a full day of deck work and other science exploits. I worked for about three hours straight and was only able to get through five animals and emerged from the small windowless cold room stiff and cross-eyed from the intensity of it all. Not everyone is on board is able to do the dissections, so each watch has a few specialists. On my watch Arthur, Linda and Fabio are the main cutters and on the night crew it is Liz, Pavica and Ari. I will be trained on other species later in the trip. I hope to share some successful dissection stories in future logs.