LTER Research Cruise Part I

[Written by Elizabeth Leonardis for our old blog, So Civilized]

The reserach Alex & I are contributing to down here at Palmer Station, is part of the larger research project, Palmer Long Term Ecological Research (LTER). Since 1993, the scientists of the LTER project have spent the month of January on an oceanographic research cruise along the Western Antarctic Peninsula (WAP), compiling a data set inculding bacteria, phytoplankton, zooplankton and on up to the top of our small food chain, penguins.

Our month began when the Gould arrived January 3rd , chocked full of scientists and their reserach teams. Oscar Schofield (Alex’s PhD advisor) headed up our group, which was the Phytoplankton/Bio-Optics componenet of the LTER. The lead PI (prinicipal investigator) Hugh Duckow decided that everyone needed a fun day off the boat before the intense month of science began. That meant a quick trip to Torgersen Island to see the penguins and zodiac around the Palmer area. We ended up getting a brillant show by a small group of Humpback Whales on the way to Torgersen. Andrew McDonnell, a graduate student also doing phytoplankton work on the LTER, captured these incredible shots of the whales.

After a quick trip to Torgersen to introduce everyone to the penguins and so I could say goodbye to my favorite friends here on station, it was time to start the real work.

The ship left early on the morning of January 5th and by 10am we were out on the back deck lowering our first instrument into the ocean. Our work consisted of lowering our insturment cage with AC-9 , CTD, and backscatter (all to measure properties of light in the water column as well as temperature and salinity), followed by the “spear” a hyperspectral radiometer (also measuring light properites but requiring sunlight to make its measurements).

Following all our light measurements, a CTD is lowered to the ocean floor. Depths ranged from 100 meters at some of the stations close to shore, up to 3000 meters at a few offshore stations. The CTD consists of a rosette, or ring of 24 go flow bottles, similar to the ones we use to collect water at Palmer only these can hold 12 liters compared to the 2 liters we collect off our zodiac.

Bottles are triggered at different depths and our group collected and filtered water for Chl a measurements, HPLC (pigment analysis), primary production of phytoplankton using radioactive 14C, CHN (Carbon, Hydrogen and Nitrogen) and nutrient anaylsis. Many of these samples are to be analyzed by us back at Palmer Station or back in the States at our home institutions. Ducklow’s group also collected water from the rosette to do various microbial measurements, inclucing bacterial primary production.

After all the exciting seawater collection, a VPR (which takes images of the particles in the water) was then deployed by Andrew and his advisor Ken Buessler, followed by net tows for zooplankton (the small animals in the ocean that feed on phytoplankton and in turn are consumed by penguins, seals, and whales as their primary source of food).

On this particular day the net tow was virtually all salps and there were thousands of these gelatinous critters who usually form chains and looked a bit like sea snakes to me. Not surprising judging by this net tow, they are most abundant in the Southern Ocean.

A “fun” tradition on cruises is to taste some of the critters that are collected. Due to the abundance of salps on this day many people took the opportunity to give them a try, me included. Photos were of course taken to document the event.

This was the typical run down at each station and took us anywhere from 5-8 hrs to complete. We followed transect lines that run perpendicular to Palmer Station at about 64ºS to just north of 70ºS, doing anywhere from 1-4 stations per line (about 200 km). Once a station was completed we steamed to the next and started sampling as soon as we arrived. This meant we were often working through the night, but lucky for us we were traveling south so the daylight hours only got longer.