Weekly Science Report 6: LMG 02-05 Southern Ocean GLOBEC
Cruise days 2-9 September inclusive
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
Cruise overview to date:
The week began abruptly with a
minor incident involving the Dush-5 winch, though no one was injured and only
minimal equipment damage was incurred. The problem was quickly traced to
a faulty winch control, which was replaced and the CTD system checked over before
the evening cast using the Dush-4/fantail CTD configuration. The
remainder of the week was rather unremarkable but very productive despite our
needing to relocate the LMG several times when our floes broke apart or the
ship could not hold position with light winds and loose pack ice. All
science groups were able to conduct operations including the Seal team, which
had not seen many workable animals in some time. We are beginning to wrap
up operations, pack gear, and prepare for our port calls at Palmer Station
The LMG continues to occupy Process Station #3. This site is unlike our previous two locations because we are able to move about on our own. There are no sufficiently large ice floes upon which we can maintain a continued presence. Therefore, we have been picking a “floe of the day” each morning and gathering as much data as possible during the day before moving off to a new floe the following day. Also unlike our previous stations, the scuba dive team found and collected krill from the underside of the ice.
The LMG is occupying a relatively small floe (40 meter diameter) for a second consecutive day. The scuba divers have had good success at this site and the ice deployed their third and final drifter buoy. We were treated to a gorgeous sunrise (now about LT) and a visit from a single emperor penguin in the morning.
Somewhat surprisingly, the LMG has continuously occupied the same relatively small floe for a third consecutive day. We have seen the pack loosen up and begin to re-freeze as the light winds have shifted slightly and the air temperatures have dropped. This area looks completely different than it did just a short while ago when we arrived early this week. The Ice team and the Krill team have had very good success here and the Seal team is pitching in to help wherever possible.
The LMG moved off the floe we've occupied for the last three days, conducted CTD casts last evening and this morning, then repositioned alongside a large, thick floe with heavy snow cover to work for the day. Three crabeater seals have hauled out just aft of the ship. Meanwhile, the scuba team and the ice corers have been busy collecting samples. The Seal Team was finally able to work on another crabeater in the evening. Although all their satellite tags were deployed early in the cruise, they are still able to make physiological studies. We are seeing some rather significant relative motion between floes due to a slight swell running through the area.
The LMG continues to operate in the same general area, though on a different floe from yesterday. The Ice Team recruited help from others on a beautifully clear day and collected many meters of core, and the divers completed two dives. Everyone is pleased with the amount of work we're accomplishing, but we're starting to think about port calls and heading home.
The LMG found a good ice floe yesterday so we are continuing to occupy it today. The Ice team is collecting cores and optics measurements, the Dive team currently made 3 dives, and the Seal team was able to complete measurements on another crabeater seal. We are definitely making productive use of the last few science days of GLOBEC IV.
The LMG was not able to maintain position against the floe we worked on the past two days, but we quickly found another location in the immediate vicinity this morning. After lunch the Ice Team went out to make optics measurements and the Dive team made two dives. We are seeing lots of seals in the area, and one hauled out relatively close to the ship so the Seal team was able to complete measurements on their 15th seal.
have completing our final day of on-ice science from the LMG, though analysis
of samples in the lab will continue for some time yet. The Dive team
completed three dives and the Seal team completed their 16th and “last”
seal. We are communicating with both the NBP and Palmer Station to
coordinate activities for the next few days, and to think about preparations
for the upcoming port call in
Individual group reports:
BG-232 – Seal Foraging Ecology (Costa, Shaffer, Barnes, McDonald, and Kuhn)
The last seal we worked with was on 16 August, since that time we have either not seen seals or were not in a position that allowed us to work with them. This all changed when we came to Process Station 3. In this region we have seen many seals in the water with a few hauled out that were too far away to safely reach. Finally on 5 September a seal hauled out immediately behind the ship. However, the ice was very loose and although the floe was behind the ship it would have required crossing several loose floes to reach it. After some discussion we decided to wait until the other research teams were off the ice or out of the water. Once the other groups were back on board we were able to maneuver the ship to use the personnel basket to reach the flow. We were thus able to capture out first seal in almost 3 weeks. Our luck continued as seals hauled out nearby the ship on 7 & 8 September. Although we had deployed all of our tags we still had physiological measurements to complete. These included measurements of the animals oxygen stores, which are the primary determinate of diving ability. Measurements included blood volume, muscle myoglobin and blood hemoglobin content. We used the time between captures to analyze our samples from the first part of the cruise allowing the development of other sampling protocols that we were able to test on these last three animals. We also collected data on the animals’ body mass and composition, as well as blubber biopsies for estimates of diet from free fatty acid analysis. This will bring our total number of seals captured during this cruise to 16; twice the 8 we captured during the winter cruise last year. Our total for the entire 2-year, 4 cruise GLOBEC field program is 44 crabeater seals and one leopard seal. We are now cleaning up and packing our gear and looking forward to the trip home.
BG-235 - Sea Ice Microbial Communities (Adkins, Blees, Cunningham, Hartsough, Fritsen)
As we have drifted north, the floes have become smaller and the pack is generally breaking up. It has become difficult to stay on one station. We have taken on the strategy of quick (one day) ice stations, assuming that we will not be there long. In the last week we have had 4 ice stations. Ice sampling has continued although we have largely had to forgo transects and other physical characterization in favor of quickly isolating different biotic environments and sampling them. Forty-eight ice cores were collected in efforts to determine integrated biomass of sea ice microalgal communities, and nutrients and salinity characterization. Work continues in conjunction with OG-241 at the optics sites to co-characterize optical environments and their associated biota. In addition we continue work with BG-244 to try to sample from the surface algal communities that they have identified during dives.
We have continued to find enhanced algal biomass (>20 micro grams per liter) in cores measuring over 70 centimeters in length. The distributions of the peaks in biomass in all cores have been distributed at all depths in the ice core profiles. Production assays on these communities indicate high potential for in situ production and in situ photo-adaptation. Further observations and experimentation at the northern most stations has noted the early onset of the spring bloom occurring in the ice.
OG-241 Optical Environment of
In the last week we have concluded on ice operations for
BG-244 - Winter Ecology of Larval Krill: Quantifying their interaction with the Pack Ice habitat (Quetin, Hessell, Willis, Boch, Oakes, Johnston and Dovel)
This week we occupied the northern-most Process Station, #3, and, for the first time on the cruise, found krill larvae directly associated with and feeding on the pack ice surface. The weather during the week was relatively mild, and we dove daily. We completed 18 dives this week and found larvae on every dive except one, which made for a very productive week. During this station we collected krill for experiments on instantaneous growth rates, fecal pellet production and whole body fluorescence, preserved krill for analysis of condition factor and measured samples for length frequency and stage analysis. Due to the relatively loose pack ice, this northern-most Process Station was a series of locations close to each other, so some of the transect methods used at other stations were not feasible. At this station we were able to collect a set of 77 suction samples from ice surfaces, which will enable us to assess the variability of the microbial community within and between the three process stations occupied during the cruise. Appropriately, on our final day of sampling, September 9, we were again swimming with a group of curious crabeater seals, a fitting end to a productive cruise with a great group of people on board. To thank any one person for the success of this cruise would be inappropriate. Thank you all, from the bridge to the mid-decks to the engine room for your help, good nature and willingness to put up with our crazy, hard working group.
Daniel Costa, Chief Scientist and
Karl Newyear, Marine Projects Coordinator