During the 28th of May, the krill patch study continued in the northern portion of Marguerite Bay. Our current position at 1714 (local time) is -67 51.396°S; -68 24.300°W. The winds are in the 10 to 15 kt range out of the north (011) and air temperature is -0.7°C.
During the early morning hours of 27 May 2001, BIOMAPER-II was towyo'd across a northern section of Marguerite Bay in order to fill in sections of the survey lines missed when the towed body was being repaired. It was brought back on deck to facilitate steaming to the Faure Islands before first light where a second Automated Weather Station was installed. It was placed at the top of a small island (approximately -68 05.5°S; -68 48.75°W) just to the east of Dismal Island in the Faure Island group, which is located in the northern portion of Marguerite Bay. Winds during the day were in 18 to 22 kt range out of the north-northeast (020). While the heavy cloud layers and occasional snow kept the region looking gloomy during the short period of daylight, working conditions were reasonably good and the installation was done before the last light of the day had disappeared. The small group of islands were also a good working site for those interested in the diet of penguins. A couple of hours after the first Zodiac load of gear and people were offloaded on the island, a second group was ferried over to a second small island adjacent to the first where penguins had be sighted. They managed to catch six penguins before darkness forced their return to the Palmer. The nighttime period was devoted to surveying the Lebeuf Fjord with BIOMAPER-II, looking for high concentrations of adult krill. Once located, an adaptive sampling approach was taken in an attempt to define the boundaries of the patch.
Eileen Hofmann reports that the activities for the CTD group in regard to acquiring additional hydrographic data were limited to making five XBT drops during the transit to the Faure Island for deployment of the second Automatic Weather Station. These temperature data continue to confirm the presence of an intrusion of Circumpolar Deep Water into Marguerite Bay.
Since no CTD casts were planned during the time that the AWS was being installed, two members of the CTD group, Rosario Sanay and Baris Salihoglu, participated in the activities of the bird research group. They learned about capturing penguins, penguin stomach pumping, and processing of diet samples. Again, thanks go to Chris Ribic and Erik Chapman for continuing the education of physical oceanographers in biological science.
Chris Ribic and Erik Chapman reported that on 27 May, they diet sampled six Adélie Penguins from the Faure Islands. Four of the diet samples contained fish and krill and two of the penguin's stomachs were empty. Otoliths were taken from two samples for identification of species and size-class of the fish. The krill in the samples were adult Euphausia superba between 48 and 56mm in length.
Ari Friedlander reported that on 27 May, the ship was in place during
daylight hours just east of the Faure Islands while an automated weather
station was assembled and while penguin work was done. The seas were light
to moderate with overcast skies, giving way to cloudy conditions and partial
clearing to the north. Incidental observations were made during the day,
but no whales were sighted. Again, humpback whales were heard, and determined
to be north and east of the ship's position.
BIOMAPER-II/MOCNESS report (P. Wiebe, C. Ashjian, S. Gallager and
BIOMAPER-II was put into the water around 1930 on 27 May near the site of the AWS installation. The purpose was to survey the northern reaches of Marguerite Bay for a large krill patch in which to do a study to determine the effectiveness of the high powered strobe light in reducing the avoidance reaction of krill to the 1 m2 MOCNESS. From the Faure Islands, a series of way points were used to define three transects across Labeuf fjord. Along the second transect line, we came into a fairly intense layer of krill located between 40 and 90 m that became more intense as we went along. Towyoing of BIOMAPER-II was mostly between 15 and 150 m, although we did one down to 250 meters so that we could get into another layer, which started about 200 m below the surface and went down to 380 m. In that layer were mostly copepods, polychaete worms, pteropods, and salps, but not krill. The big adult krill were in the shallow layer and as the patchiness became more intense, the VPR images of the adults increased. Just before mid-night, the patchy layer ended abruptly and an adaptive sampling plan was used to try to define the horizontal dimensions of the layer. This involved steaming in different directions across the geographical are in which the layer of high krill backscattering occurred until the edges were evident. While the patch of krill was five to 10 kilometers in horizontal extent, it proved illusive. It took most of the nighttime just to map it out and find a suitable place to do the net towing. As a result, no MOCNESS tows were taken during the 27th of May.