Report of Activities on the RVIB N.B. Palmer Cruise 02-04

5 August 2002

According to the Geographic Names of the Antarctic, Crystal Sound was so named relatively recently in 1960 “...because many features in the sound are named for men who have undertaken research on the structure of ice crystals.” It is an apt name also because ice dominates the seascape in the area now. Our transit to the Sound ended about 1230 on 5 August at a station south of Watkins Island (-66º 31.37′S; -67º 16.15′W). In contrast to yesterday, which started off bright and sunny, dark clouds hung low most of the day blending in with the pack ice so that the horizon was often not visible. Although the Palmer moved easily on two engines through the pack ice for a good portion of the steam down to the Matha Strait entrance to Crystal Sound, as we made the approach to the strait, the ice pack thickened significantly and the power of four engines was needed to get us into the sound and to our first working location. During the late evening of 4 August while steaming southwest out along the outer margin of the series of Islands leading to the study site, radio communications with the L.M. Gould revealed that they were steaming into Pendleton Strait and would head south to the east of Lavoisier Island down to Crystal Sound rather than following along our trackline, which lay to the west of the Island. They thought that by taking that route, they had a better chance of encountering seals and penguins to work on, although as noted below, a number of sightings were made from the Palmer.

First up in the science program for the two and a half day stay in the sound was a SCUBA dive under the ice to look for krill larvae and other zooplankton that live in close associated with the undersurface of the pack ice. The dive was done from a Zodiac boat in a frozen lead opened up by the Palmer. The dive went well, although one of the diver handlers dressed for the cold, but not for in-water work, slipped getting down the ladder into the Zodiac, and took a short plunge. Another person quickly got suited up and took the place in the boat, while the other, unhurt, dried out. Interestingly, no krill were observed during the dive. During the dive, the first CTD cast was undertaken and as described below, went well. BIOMAPER-II was deployed for a calibration run off the stern of the Palmer after the divers returned, and the evening ended with the starting of a series of CTD casts in a transect line across the Matha Strait inlet to Crystal Sound.

The weather during 5 August was dark, dreary, and cold, although the wind stayed moderate (15-20 kts) to low (<10 kts) all day. The air temperature started out in the early morning hours at -9.4ºC and the barometer reached a peak of 1019.2 mb. By evening, the air temperature had warmed some to -4.7ºC; the barometer remained high (1018.6 mb). The sea water temperature was at the freezing mark (-1.824ºC).

CTD Group report (Eileen Hofmann, Bob Beardsley, Baris Salihoglu, Chris MacKay, Francisco (Chico) Viddi, Sue Beardsley)

We arrived at a site just inside of Crystal Sound about mid-day today. This site was designated as a test station for a range of activities and instruments. Following the test dive by Torres and group, the CTD/Rosette system was deployed for a test cast. The purpose of this cast was to check the functioning of the CTD, to provide experience in deploying/retrieving the CTD from the Baltic Room, and to test the software used for acquisition of data from the CTD. Also, water was obtained from the Nisken bottles mounted on the Rosette for calibration of the AutoAnalyzer used for nutrient analysis (Fanning Group), for dissolved oxygen titrations and salinity determinations, and for microzooplankton experiments (Gallager Group).

The CTD was lowered to 500 m (bottom depth of 679 m), which is deep enough to test the software and sensors. It is also deep enough to obtain water for the nutrient and oxygen analyses, i.e., the deeper waters have a more consistent concentration. Eighteen of the 24 Nisken bottles were closed at 500 m. Four additional bottles were closed at 300 m, 100 m, 50 m and the surface. These latter bottles provided water for the microzooplankton experiments.

The deployment of the CTD went well, in spite of it being the first cast. The data acquisition software and CTD sensors seem to be working as they should. The Nisken bottles worked and none appeared to be leaking.

The vertical profiles of temperature, salinity and oxygen obtained from the cast showed a thick (about 80 m) Winter Water layer at the surface. Below this the temperature warmed to 1.4ºC at 500 m, and oxygen concentration decreased to about 3.8 ml/l. Salinity increased with depth to about 34.72. These hydrographic features are indicative of Upper Circumpolar Deep water. This water mass originates at the edge of the west Antarctic Peninsula continental shelf and must be moving into Crystal Sound via a deep trough that connects this region to the outer shelf. We have planned a small-scale CTD survey for Crystal Sound that we will do during the next 2 to 3 days. One objective of this survey is to determine where Circumpolar Deep Water enters Crystal Sound.

Sea Birds (Chris Ribic and Erik Chapman)

Floes of first year ice, about ¾ m thick, characterized the area covered by the ship today as we headed into Matha Strait and Crystal Sound. The ice ranged from 9 to 10/10ths coverage and bird observations were taken for approximately 4 hours during the day. Surprisingly, very few flying birds were observed, even in areas where there was some open water. However, as we entered Matha Strait and began to move east toward Crystal Sound, the ship began to travel through more open water and 2 Snow Petrels and 3 Antarctic Petrels were observed. Eight Emperor Penguins, including 2 juvenile birds, were observed throughout the day in 3 separate sightings. Thirteen adult Adélie Penguins in 3 different sightings were also observed. Nine Blue-eyed Shags, typically seen within 10 miles or so of land, were also observed today. Twelve seals, including Weddell and Crabeater Seals, were observed both in the water and hauled out on floes.

In the afternoon, the ship approached the Barcroft Islands, where 14 diet samples were taken from Adélie Penguins during the April cruise. It appeared that there was at least some open water around these islands and perhaps this area may still be serving as a haul-out area for Adélie Penguins foraging in Crystal Sound. Hopefully, there will be enough open water so that we could explore this area by Zodiac tomorrow afternoon to see if we can find penguins returning from foraging trips.

Marine Mammal report (Chico Viddi)

As wonderful as Antarctica is, today (5 August) it showed us how variable it can become. Effort could only start at 0915 this morning (local time), since light was optimal only then. The day was dark, cloudy, and foggy, and ice coverage was at least 9/10 all day. Therefore effort was mainly focused on the open water in the wake by the vessel. Viewing conditions were very poor, so we just achieved 1 hour 45 minutes of observation effort. No cetaceans were seen, but many crabeater seals were observed. The survey ended at 1514 (local time) because of the poor observing conditions, but also due to the vessel stopping for the first station work in Crystal Sound.

Current Position and conditions

We continue to work in Crystal Sound in substantial pack ice and our position on 6 August at 2352 is -66º 41.694′S; -67º 07.540′W. The air temperature is -9.2ºC and the sea temperature is -1.816ºC. Winds are calm and the barometer is at 1015.4 mb. The skies are cloudy.

Cheers, Peter