Weekly Science Report 2: LMG02-05 Southern Ocean GLOBEC

Cruise days 5 August to 11 August inclusive

I. LMG 02-05

a. Mission statement: The U.S. Southern Ocean Global Ocean Ecosystems Dynamics (U.S. SO GLOBEC) Program is in its second and final field year. The focus of this study is on the biology and physics of a region of the continental shelf to the west of the Antarctic Peninsula that extends from the northern tip of Adelaide Island to the southern portion of Alexander Island and includes Marguerite Bay. The overall goal is to elucidate shelf circulation processes and their effect on sea ice formation and Antarctic krill distribution, and to examine the factors that govern krill survivorship and availability to higher trophic levels, including seals, penguins, and whales.

This is the second of two joint cruises. The first occurred in April-May and this, the second cruise that is occurring from July 29–September 19, 2002 onboard the RVIB N.B. Palmer, which is carrying out a broad scale survey, and the ARSV L.M. Gould, is conducting process-oriented studies. The goal of the process cruise aboard the ARSV L.M. Gould is to provide a more detailed examination of the biological and physical processes that are occurring in this region that can be put into the shelf-wide context supplied by the broad scale survey being carried out at the same time on the RVIB N.B. Palmer.

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 Western Antarctic Peninsula Region

BG-244-0 Quetin/Ross – Winter Ecology of Larval Krill: Quantifying their interaction with the Pack Ice habitat

c. Cruise overview to date

5 August

The LMG made good progress to the south, inshore of Lavoisier Island last night.  Before breakfast 4 workable Adélie penguins were sighted and two were eventually captured and tagged.  Less than half an hour after penguin operations were complete, two crabeater seals were located and sampled.  Less than half an hour after that operation was complete, another workable seal was sighted.  This slowed our southerly progress, but compared to last year has gotten the predator groups off to an excellent start.

6 August

The LMG made some southerly progress towards Matha Strait throughout the night, punctuated by the capture and tagging of several penguins.  We have met up with the NBP and are working within visual range of each other (at least when the fog lifts).  The seal team had a successful morning; as they captured and tagged their 3^rd crabeater seal.  After lunch several more penguins were captured and sampled.

7 August

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 1^st process station at the southern most region of the survey grid.

8 August

Today was spent in transit to the southern most part of the survey grid.  The day started at midnight when we rendezvoused with the Palmer to begin our trek through Matha Strait.  This turned out to be tougher than we planned as we spent much of the day stuck, trying to work our way out of the ice. Much of the daylight hours were spent backing and ramming by both ships.  However with a combination of Capt. Robert’s skill and persistence along with considerable assistance from Capt. Joe and the power of the Nathaniel Palmer we finally got out of Matha Stain and into smooth going. 

9 August

The LMG made good progress toward the southwest and Process Station #1 throughout the night following the NBP parallel to the west coast of Adelaide Island.  At approximately 0900 this morning a group of ~50 Adélie penguins were sighted.  A number were captured and sampled.  The seal team captured and tagged their 6^th crabeater seal, and the dive team completed another dive collecting juvenile krill.  It has been a successful day for all science groups aboard.  We plan to continue to the southwest overnight.

10 August

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.

11 August

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 Crystal Sound just east of Lavoisier Island. The two female seals tagged on 5 August weighed 385 kg and 268.5 kg. This is the largest animal tagged this year and is the second largest seal tagged during our two-year study. The largest seal tagged was also a female, weighing 413 kg tagged May 2001 in Lazarev Bay. On August 6 we tagged a single female crabeater seal that weighed 294.5 kg, on August 7 we tagged two female crabeater seals, (238, 207 kg) and a sub-adult male leopard seal (197.5 kg). Although, we were prepared to tag any of the Antarctic pack ice seals (crabeater, Ross, Weddell, leopard seal), we had not initially planned on tagging a leopard seal this early in the cruise. During the afternoon of August 7, we spotted what we thought were two crabeater seals laying next to each other, so we decided to capture both of them. However, the first “crabeater seal” was awfully frisky after injection and once we got a decent look at it, we realized it was a sub-adult leopard lying next to a crabeater seal! So we decided to take advantage of the opportunity and completed a full workup of our first leopard seal. Our next crabeater seal was captured and tagged on August 9 during the transit south to the first process station. This animal weighed 273 kg and was our first male crabeater seal. We were able to obtain a complete set of morphometric measurements (body mass, blubber thickness, length, girth), and we collected blood and other tissue samples. We passed many crabeater seals in transit to Ice Station Sparky and are hopeful that we will see more at the southern most station.

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 transiting along Lavoisier Island, we were able to deploy 3 dive depth satellite transmitters and 5 SPOT location satellite transmitters on both male and female birds. Additionally, we were able to lavage 8 birds finding primarily empty stomachs with the occasional amphipod or digested krill. Once we reached the southern edge of Adelaide Island (50 miles from the shore), we encountered a group of 40 Adélies on a viable floe. We captured 9 penguins total: 4 birds, including a juvenile, were outfitted with SPOT transmitters and 5 were lavaged. Once again, the stomachs were empty excepting a squid beak in one bird. In the afternoon, we caught 3 more birds for diet sampling and found they had been eating very little.

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 Crystal Sound area. Phytoplankton biomass (measured as chlorophyll a was low) averaged 0.35 to 0.40 micrograms per liter in the upper mixed layer (mixed layer was only ~ 30 meters).  Two late night ice stations were conducted in Crystal Sound. One (named Ice Station Levy) was on relatively young first year ice averaging 50-70 cm thick and the second (named Ice Station Bergy bit) was on an older first year ice floe that had more deformation and ridges. Cores were taken for analysis of structure (along with OG-241), temperature, salinity, nutrients, bacteria numbers and biomass and algal identification and biomass. Brine samples were collected for productivity assays. Chlorophyll a concentrations in ice cores ranged from 0.2 to 13 micrograms per liter (average of ~ 0.8 micrograms per liter). Nilas, collected next to the ice floe at ice station Bergy bit had 0.7 micrograms of chlorophyll a.

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, 1^st year ice 75cm thick, rafted and ridged 1^st year ice 300 cm thick, and 1^st 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.