Weekly Science Report 2: LMG02-05 Southern Ocean GLOBEC
Cruise days 5 August to 11 August inclusive
I. LMG 02-05
is the second of two joint cruises. The first occurred in April-May and this,
the second cruise that is occurring from July 29–
b. Projects represented on the process cruise
BG-232-0 Costa/Burns/Crocker – Foraging Ecology of Crabeater seals
BG-234-0 Fraser – Winter Foraging Ecology of Adélie Penguins
BG-235-0 Fritsen – Sea Ice Microbial Communities
OG-241-0 Smith/Martinson/Perovich – Optical Environment of the
BG-244-0 Quetin/Ross – Winter Ecology of Larval Krill: Quantifying their interaction with the Pack Ice habitat
c. Cruise overview to date
The LMG made good progress to the south,
The LMG made some southerly progress
The LMG made a rendezvous with the NBP last night to allow each ship to exchange needed items. Ice conditions prevented zodiac operations so a bow-to-stern exchange using cargo nets was performed. The LMG hove to overnight. Today the predator groups were quite busy. The morning started out with the penguin group catching birds and then moved onto the seal group who caught 2 crabeater seals and one leopard seal and then finished with the bird group catching additional penguins. The scuba divers were able to get into the water and collect krill samples. Once everyone was on board we began our southward journey to establish the 1st process station at the southern most region of the survey grid.
Today was spent in transit to the
southern most part of the survey grid. The day started at when we rendezvoused with the Palmer to begin our trek through
The LMG made good progress toward the
southwest and Process Station #1 throughout the night following the NBP
parallel to the west coast of
The LMG followed the NBP towards the southern end of the SO-GLOBEC grid. Ice conditions varied from heavily rafted rubble fields to relatively uniform floes with diameter 10-20 meters. The barometer continued to drop, but the weather remained rather comfortable. Throughout the day many crabeater seals were spotted, but the seal team decided to wait until we reached the first process station to hopefully deploy their remaining tags.
The LMG continued to follow the NBP to the vicinity of GLOBEC Survey station #76. It was determined that the ice types here were acceptable to establish a Process site, and further progress to the east was deemed impractical due to thicker and more heavily rafted ice slowing our forward progress. In the afternoon we established our “campsite” and completed another trade of items with the NBP. While the LMG groups were establishing their study areas, the NBP stood off from us and conducted a CTD cast and accomplished other tasks. We anticipate remaining in this location for the next week while conducting ice and snow surveys and under-ice dive operations. Predator sampling will occur opportunistically as animals appear within easy reach. We faced the coldest temperatures yet with the thermometer reaching -18°C or 0°F! Working outside at these temperatures for prolonged periods is very tiring.
E. Individual group reports.
BG-232 (Costa, Shaffer, Barnes, McDonald, and Kuhn)
We have had considerable success
over the past week. To
date we have captured and tagged 7 seals, 6 crabeater and 1 leopard seal. Four of the crabeater seals and the leopard
seal were tagged in the
BG-235 (Heidi Geisz, Brett Pickering)
The first week of GLOBEC IV
cruise proved successful for our team.
Finding plenty of Adélies on ice floes while
BG-235 (Fritsen, Hartsough, Blees, Cunningham, Adkins- Desert Research Institute)
During transit periods from Punta Arena and Palmer Station we have conducted hourly ice observations that include observations of visible algal material in the ice. Already this year we are seeing “colored” ice in the study region. This is in stark contrast to last year when we did not see one piece/bloc of colored ice the entire cruise on board the L.M. Gould.
During the first week of “on-ice”
science operations, we conducted opportunistic ice and water column sampling
while watching the predator science teams tag penguins and seals. Two CTDs were run in the
Photosynthesis irradiance assays conducted on brine and slush samples gave preliminary evidence for photoadaption to in situ irradiances along the vertical profiles, which indicates production processes are occurring throughout the vertical ice profiles. This is not overly surprising considering that the ice column has been relatively warm (above - 2.5ºC) and these temperatures do not prohibit production and growth of sea ice algae.
Microscopic examination of a small number of ice samples have shown a large range of species richness, with some samples being mixed assemblages (included diatoms: Fragilariopsis sp. (likely curta), Corethron sp., Amphiprora sp., Chatocerous sp. and a myriad of thecate dinoflagellates) as well as some samples with low species numbers (these were dominated by dinoflagellates).
Ice Station Sparky (named in honor of the Marine Tech's birthday) was established on JD 223 and we began ice thickness transects, sampling and daily CTD operations. The ice station is located in first year ice ranging in thickness from 30 to 50 cm in the areas of the floes that have not experienced deformation. The small ridges next to the ship are measuring 2 to 4 meters in thickness. Despite air temperatures being -15ºC the floes are flooded with seawater and slush is prevalent on the flats as well as within the snowdrifts. The slush is currently in the process of freezing. However, this morning's air temperatures are only -5ºC and it is unlikely these temperatures will allow the slush to freeze in the next few days.
We will continue sampling the ice throughout the day and initiate physiological assays in the upcoming week.
OG-241 (Bruce Elder and Kerry Claffey, Cold Regions Research and Engineering Laboratory)
In transit to our first long term process station “Sparky” we sampled 4 different ice floes in conjunction with BG-235 and BG-244. The 4 ice types were Nilas, 1st year ice 75cm thick, rafted and ridged 1st year ice 300 cm thick, and 1st year ice 140 cm thick. Two of the ice stations were longer-term stations. Transect lines were laid out to measure the variability of snow and ice thickness. We sampled a snow pit for snow properties. At each site 4 ice cores were taken for temperature, salinity, d18O, and ice crystallography as well as measurements by other project. All ice cores were collocated for data comparison. The other 2 stations were quick stations where just ice cores and brine were taken.
BG-244 (Quetin, Hessell, Willis, Boch, Oakes, Johnston, Dovel)
The first week of the cruise has gone well for our project during transit to the first process station. Our divers new to Antarctic conditions did their first dives during a scheduled stop at Palmer Station. All went well. None of the divers lost their enthusiasm for diving in Antarctica. On the transit south, which was primarily for predator work, we dove opportunistically at three locations. Though early in the cruise, we have not seen krill larvae in the abundances observed last season. We collected krill larvae from the underside of the ice east of Lavoisier Island and west of Adelaide Island. Krill from both collections were staged, measured for total length, preserved for measurements of condition factor and their instantaneous growth rates determined. Furcilia 6 stages dominated the collections.