Weekly Report 2: LMG02-03 Southern Ocean GLOBEC

Cruise days 14 April to 28 April inclusive

 

I. LMG 02-03

 

a. Mission statement: Our 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.

 

b. Projects represented on the process cruise

 

BG-232-0 Dan Costa and Jennifer Burns - Seal ecology

BG-234-0 Bill Fraser - Seabird ecology

BG-236-0 Kendra Daly - Krill ecology and physiology

BG-237-0 Rodger Harvey - Krill biochemistry

OG-238-0 Laurie Padman - Mesoscale circulation and hydrography

OG-240-0 Eileen Hofmann - Circulation, hydrography, modeling

BG-239-0 John Hildebrand-Cetacean biology

BG-245-0 Jose Torres - Krill and fish ecology, krill physiology

BG-248-0 Meng Zhou - Krill ecology, behavior, and modeling

Nutrient Analyses - Jeff Morin

 

c. Cruise overview to date

 

07 APR 02 LMG departed PA

12 APR 02 LMG arrived Palmer Station

13 APR 02 LMG departed Palmer Station for first study site, process station 7, Crystal Sound and Hanusse Bay on the western Antarctic Peninsula Shelf. Visited Vernadsky Station enroute, dropping off supplies and taking advantage of the available time in quiet water to calibrate our HTI 120/38 acoustic system.

14 APR 02 Arrived process station 7, initiated sampling.

17 APR 02 Departed process station 7

18 APR 02 Arrived at Avian Island, dropped off penguin field party, began process station 5: Laubeuf Fjord.

20 APR 02 Dropped off seal field party at Rothera Base, continued with station 5 ops.

23 APR 02 Rendezvoused with RVIB Palmer, departed station 5

24 APR 02 Arrived station 1, initiated sampling

27 APR 02 Departed station 1

28 APR 02 Arrived Avian Island, picked up penguin field party. Departed Avian Island, arrived at Rothera Base to pick up seal field party.

 

d. Synopsis

 

During the first two weeks of the process cruise three stations were completed. Our shipboard operations were complemented by the stand-alone field efforts of our seal and penguin teams during the LMGs offshore sampling.

 

Station 7. Station 7 was created as a mini-station during the last 2 d of LMG 01-04, the fall 2001 process cruise, when we found it to be an area of high krill abundance. Tagged seals used it extensively as a hunting area during the winter of 2001. It clearly merited further study and was chosen as our first study site for 2002. It is bounded on the north by the northern end of Lavoisier Island, on the south by the southern end of Hanusse Bay, on the west by Matha Strait, and the east by longitude 66o 30' W.

 

We arrived at station 7 at first light and began our operations with a successful seal survey along the east coast of Lavoisier Island, which set the tone for what has been a terrific cruise. We have followed a strategy similar to last years process cruise which is to devote the lions share of daylight hours to the projects that are most light dependent, viz. our seal and penguin projects. One very clear difference between this year and last year is the presence of considerable sea ice left over as relic floes from last years winter cover, and sea surface temperatures over a degree colder.

 

During our stay at station 7 we completed three CTDS , two MOC 10'S, two MOC 1'S, and two ADCP/HTI surveys, in addition to six Tucker trawls and a large suite of lab experiments. Our seal team instrumented and worked up four seals, and our penguin team sampled diets in two Adlie penguins. At completion of our sampling in the Crystal Sound region we originally planned to move south down the inside track, staying to the east of Adelaide Island by skirting the west coast of Laird Island down through Hanusse Bay, into Tickle Passage, through The Gullet, and through the Barlas Channel and down into Laubeuf Fjord, our station 5. Unfortunately, we were stymied by heavy ice cover in southern Hanusse Bay, an area that was totally ice free on the 29th of May in 2001. Consequently, we ran around the west coast of Adelaide Island to reach Avian Island, and to enter Laubeuf Fjord from the south.

 

Station 5. Following the drop-off of our penguin team at Avian Island, we began an ADCP/HTI survey covering the mouth of Laubeuf Fjord and running the length of it to Day Island. At the conclusion of the survey we resumed our day/night division of labor with MOC 10'S and MOC 1'S dominating the hours of darkness and seal/whale operations during the day. At station 5 we introduced diving into our daylight repertoire to look for Euphausia superba furcilia under the scattered ice floes in Laubeuf Fjord. We saw no furcilia under the ice on our first dive, in spite of considerable amounts of brown ice in the floes around us.

 

We dropped off our seal team at Rothera Base on 20 April and immediately began an ADCP/HTI survey back and forth across Laubeuf Fjord during the course of a tidal cycle. The purpose of the survey was to allow us to get an idea of the tidal influence on circulation through Laubeuf Fjord as well as distribution and movement of krill over a well defined area through time.

 

We towed our MOC 10 and MOC 1 intensively during our last two days to get a nets eye view of diel distribution patterns prior to our departure for station 1. Our rendezvous with the Palmer went seamlessly, with an exchange of chemicals and a brief visit by Captain Robert of the LMG to the Palmer Bridge. Directly after our rendezvous we headed out to the treacherous waters at the shelf break to complete our station 1.

 

Station 1. Station 1 was divided into two stations, one at oceanic depths (>3,000 m), which was dubbed station 1a and one at shelf depths (500 m) which we termed station 1 b. We arrived at station 1a in the wee hours of 24 April (01:00) and initiated our sampling with an ADCP grid across the shelf break followed by a MOC 1 and a CTD. Our nighttime sampling included Tucker trawls for live animals and MOC 10/HTI deployments. Winds were moderately high, 25-35 knots, but the sea stayed a workable 10-12 feet for our first 12 h.

 

Our schedule continued with our days divided between CTDs, Tucker trawls, and MOC 10'S/HTIs from noon-midnight and ADCP surveys and MOC 1'S from midnight to noon. We stayed a total of 4 d at station 1, losing our third day to weather. We completed 5 MOC 10'S, eight Tucker trawls, three CTDS and six MOC 1'S, three ADCP surveys and several deployments of the HTI acoustic system before departing. The weather hovered at the limits of a working sea for the LMG most of the time, with winds running from 25-45 knots and seas from 10-20 feet.

 

Our last day for the present (bi) weekly report, the 28th, included our transit and smooth pickup of our penguin team at Avian Island and the pickup of our seal team at Rothera Base. Station 1 was the first location where we captured krill larvae in quantity.

 

e. Individual group reports

 

1. BG 232 - Seal ecology and physiology - Burns/Costa

 

Week 1: April 7-13th

 

Our team (Jennifer Burns, Gitte McDonald, Millie Gray, Mark Hindell) arrived in Punta Arenas on April 4th, and had a easy move onto the ship. Raytheon had done a great job with orders and gear sorting, and with few exceptions, everything we needed was available. [two ordering glitches 2 cases rather than 2 bottles of lidocaine-HCL; 15oz epoxy bottles rather than 50ml epoxy cartridges, both easily dealt with]. We unpacked into our lab space, and battened everything down for the transit south. At Palmer Station, we did some work in the rad van, which was used first by our group and others to weigh chemicals on land (as the bio lab at Palmer was under construction). Thanks to Steve and the MTs who were willing to load the van off and on the ship during a busy port call so that we could do our science prep. We enjoyed the time at Palmer station, and recorded one tagged and branded (ST 0) southern elephant seal. We are working to track down the owner of the brand so that we can report the sighting appropriately.

 

 

Week 2: April 14-20th

 

The morning of the 14th the ship was at the northern tip of Lavoisier Island in Crystal sound. This area was a hot-spot for seals throughout the winter last year, and we were interested in characterizing the region on this cruise. The eastern coastline of Lavoisier was an ice cliff into the water, and fog lowered visibility considerably. However, as we approached the southern tip of the island, we entered an area with several large ice floes, three of which had crabeater seals hauled out. We took the zodiac out, and captured and deployed a satellite tag on the first crabeater seal of the 2002 GLOBEC cruises (Event #20). The seal was a small female, and all procedures (weight, blood sampling, measurements, body condition, blood volume, tissue samples) went well. A good start, that was promptly followed on April 15th, when we realized that Crystal sound was a hotspot for crabeater seals in the fall as well as the late winter. The ship was in the area around 66 45.225W, 66 46.555S and we were surrounded by large floes with multiple seals on them. In one day we saw more seals than we had seen during the entire cruise last fall. After a little difficulty with very alert and active seals, and with floes not being stable enough for us to work on safely, we located a floe on which 3 seals were hauled out. We successfully captured and tagged a male on the floe (PTT 13363), and then immediately moved on and captured one of the females that had remained on the floe (PTT 13365, Event #29). All procedures worked well, and we have refined our methods slightly to increase speed and efficiency. Our luck continued to hold, and on the 16th we were again in an area with abundant seals and large floes. Since we had 3 of our tags deployed already, we decided to hold onto our remaining tags until we captured a larger animal. The single seal we handled on the 16th did not meet the size criteria (was < 200kg), and so we only collected blood and tissue samples from it (event #38). Having the opportunity to be selective is a welcome change from last year. On the 17th, the ship was still in southern Crystal sound, as the high abundance of krill was of interest to many groups. As the weather held, we were again able to conduct seal searches, and this time we captured a large adult male (Event # 52) and deployed our fourth PTT (14749) on the animal. With half of our tags deployed, we are working well as a team, and have been well supported by Steve (MPC), Christian and Josh (MTs). Wed also like to thank Chris Denker, Brett, and Ari Friedlander for their assistance with the animals. With four PTTs deployed, we were well ahead of schedule, and off to an excellent start. The abundance of seals was possibly due to a large krill swarm that was located at the southern end of Matha Strait, and we were thrilled to have tagged seals out in an area of known krill abundance. The tags are working well (as determined from data sent daily to the ship) and we have already received many temperature-depth profiles from the seals. One interesting point is that the seals we handled in Crystal sound were much smaller than the seals we handled last year. Still they have been fat and healthy, so it does not appear that food is a limiting factor, just that the animals are younger.

 

The 18th and 19th were spent getting the Penguin team set at Avian Island, and doing a 24 hour ADCP / HTI survey in Laubeuf Fjord. We did not see any crabeater seals on either day, but did sight some Orca (a predator on seals). In the morning of the 20th we were off Wyatt Island, where we captured our first 3 seals of last year. This time the area was clear of ice and seals, so we proceeded south down Lawrence Channel searching for seals on suitable ice. At the southern end of the channel (67 27.364W, 67 38.900S) we located a single large female hauled out on an ice floe by herself. We took a zodiac to the seal (Event #87) and attempted to capture the animal. After several technical problems, we succeeded in restraining the animal sufficiently to get her on gas anesthesia (she destroyed one of our capture nets in the process). After that, all went well, and we deployed the fifth satellite tag of the study on this animal. We then returned to the Gould, and prepared for our evening transfer to Rothera Base.

 

As of the 20th, 3 of the tagged seals were within 20 miles of their tagging location, but one had moved 70 miles to the NE.

 

Week 3: April 21- 27th

 

We transferred from the Gould to Rothera Base in the evening of April 20th. The transfer went smoothly, and took approximately an hour to accomplish. Everyone at base was welcoming, helpful and friendly, and we immediately felt at home. Sunday, April 21st was a rest day on base, and we spent it getting acquainted with our new home, and setting up our labspace in the main building. We also went through several safety briefings, and acquainted the base commander, Simon Garrod, Dive Officer Phil Horne, and Boatman John Burleigh, with the details of our research plan. Sunday evening we presented a brief slide show about our project to everyone on base. The 22nd was our first opportunity to conduct research, but the winds were too high to permit safe zodiac operations. Instead, we walked Rothera point, and located one crabeater seal on a floe a bit offshore. This was reassuring, as it meant that the seals were in the area. That point was in no doubt on the 23nd, as we awoke to a beautiful still day. The wind overnight had blown sea ice into Ryder bay, and as we went out in boats to look for seals, we saw dozens on the floes. All in all, we counted ~100 crabeater seals on floes. While BAS boating policy does not normally support operations on floes, the fact that we couldnt reach the haulout beaches due to dense ice, and the abundance of seals on ice led both John and Phil to suggest that they ask for an exception to policy. We returned to base and spoke with BAS in Cambridge, and after providing a risk assessment of work on floes, were able to return to Ryder bay and work on sea ice. We are extremely appreciative of the efforts of Simon, John, and Phil to make this possible.

 

The effort paid off, and in the afternoon, we captured a large male seal on an ice floe upon which there were 11 other seals hauled out. We deployed PTT 14755 on this animal (Rothera Event #2) and while working on the seal spotted a pod of about a dozen Orca in the nearby ice. We were able to accomplish all procedures except weighing the animal, as the wind was blowing our floe into the side of a large iceberg, and we felt it prudent to leave the floe before the impending impact. We returned to base, and celebrated our success with those who had been so helpful.

 

By the morning of April 24th all the ice had blown back out of Ryder Bay, and we searched the shoreline of Lagoon and Anchorage Island for seals from zodiacs. Unfortunately we did not see any seals there, and we were unable to go out to Leonie Island due to worsening sea conditions. Winds continued to plague our efforts on April 25th and 26th, as we were unable to go out in boats, and shoreline searches did not find any seals. However, conditions broke on April 27th, and we were able to get out in boats. There was little ice in Ryder Bay, and we planned to search the shoreline of Leonie Island. However, on our way to the island we sighted a large floe with four crabeater seals hauled out on it. We were able to capture two of these animals and deployed our two remaining satellite tags on two large females (Rothera Event #7). While working on the animals we were visited by 3 minke whales, an Antarctic fur seal, and several flocks of penguins. It was a magical day, where everything worked as it was supposed to, and we all enjoyed our time out on the floe (despite being rained on for most of the time). We were happy to get the tags out, and not concerned that the tags were located in the northern part of the study area because seals we had tagged earlier were showing large scale movements. We returned to base to discover that the Gould would arrive the next night. We were sad to think that our time at Rothera was coming to a close so quickly, but thrilled with our success during our visit. We celebrated our success at a fancy dinner Saturday night, and thanked everyone who helped. Sunday (28th) we packed our gear, and got ready to transfer back to the ship.

 

At this point, Id like to reiterate that we received superb support during our stay at Rothera. On each trip in boats we were supported by 4 (or 5) base personnel, and we cant thank Phil, John, Rayner Piper (marine assistant), Pete Martin, Andy Chapman, and Felicity Aston enough for their help in the field. On base, everyone helped ensure that our work was a success, but also that we had a good time while guests. The time ashore was well spent we accomplished a significant amount of science, gained insight into the research program at Rothera, and made many new friends. We hope to be able to repay their hospitality in the near future.

 

2. BG 234 - Seabird Ecology - Fraser - Report by Chris Denker

 

BG-234, Seabird Component of SO GLOBEC LMG. Dr. Bill Fraser represented by Chris Denker, and Brett Pickering

 

The period from 14 April to 28 April was a very successful 2 weeks for the Seabird Group. In the Crystal Sound region we collected 4 Adlie penguin stomach samples from two groups of two birds on the 15th and 16th. The depth of the first location was 1200 meters with the majority of krill in the 41 to 45mm size class. Both of these birds (a male and female) appeared very healthy with the females sample containing fish. The second two birds were found in 200 meters of water with krill a bit smaller (36-40mm). Both of these birds were females with fish found in one. Unlike the birds found in 1200m of water, these two did not appear nearly as healthy.

 

The morning of the 17th brought us to Avian Island where brash ice surrounded the island. After pushing through the ice we landed at the survival hut on the north end of the island. The remainder of the day we spent setting up camp and securing anything and everything. We deployed satellite transmitters on the 19th, 20th, and 22nd. A total of 14 were set out with 4 of them being dive/depth. After the 22nd we spent our time collecting diet samples. From the 23rd to the 27th a total of 20 samples were collected with one day taken off due to weather. Krill size classes have varied depending on the day of collection. Adult krill in the 40mm class were found early in the week, while 25 mm juveniles dominated the end of sampling period. Fish were present throughout the sampling period. The Avian Island camp allowed us to complete a fair amount of work which otherwise might not have happened. The time allowed for the camp was sufficient to meet our objectives.

 

So ended the 14th through 28th of April.

 

3. BG 236 - Krill ecology and physiology - Daly

 

29 April

 

Shortly after leaving the Vernadsky Base and before our planned survey in Crystal Sound, we successfully completed a field calibration of the Hydroacoustic Technology Inc. (HTI) echosounder using a standard target sphere. Unfortunately, the southern end of Crystal Sound had too much sea ice to allow us to safely tow the HTI system. The ADCP system, however, detected a dense layer of Euphausia superba (verified by net tows) across Matha Strait. By positioning the Gould using the ADCP, we were able to collect over an hour of acoustic data of the layer by drifting through the heavy pack ice. The layer extended from about 35 to 300 m in depth over water 400 m or greater. As the bottom depth shoaled, the layer consolidated between about 50 to 150 m and disappeared when the bottom shoaled to about 100 m. Many of the krill collected in net tows had black-green guts and hepatopancreas indicating feeding on phytoplankton or phytodetritus. A brief assessment indicated that juveniles 17 33 mm in length were the dominant stage and size present as well as immature and mature males and females 39-47 mm. No Euphausia crystallorophias of any stage or E. superba larvae were found.

 

At our next station in Laubeuf Fjord, we completed almost 24 h of a hydroacoustic/ADCP survey of the main fjord basin in collaboration with Meng Zhou, before ice conditions forced us to bring the towed fish on deck. Last year we observed dense layers in this outflow region from Crystal Sound. The purpose of this survey was to map the density and distribution of this layer in relation to the bottom bathymetry, circulation and tidal flow to better understand how the zooplankton and fishes maintain themselves in the strong downstream current. The layer was continuously present over the main basin and up onto both sides, but disappeared when the bottom shoaled to about 75 m depth. Although the overall extent of the layer varied, it was generally 20 to more than 200m in depth, with one maxima concentrated between 30 to 120 and a second maxima centered about 150 m, during late afternoon and evening at the bottom of the fjord. There was some evidence of vertical migration. By 10AM near the top of the fjord, there was little acoustic backscattering in the upper 60 m. The layer was more compact with a maximum concentration about 180 m.

 

Net tows suggested that different species of zooplankton and fishes were vertically segregated, with Euphausia superba and E. crystallorophias being shallower than juvenile and adult Pleuragramma (fish). The occasional acoustic targets near surface were probably Themisto amphipods. Deeper targets included the mysid (Arctomysis sp.) and large amphipods (Eusirus spp.). Almost no krill larvae were found in Laubeuf Fjord or the surrounding area. Juvenile E. superba appeared to be the dominant size class similar to the krill population in Crystal Sound. Live individuals of all the above species were given to Dezhang Chu during a rendezvous with the Palmer to determine their acoustic material properties (the sound speed contrast and density contrast of an individual relative to the surrounding seawater). These measurements will help interpret the acoustic backscattering data.

 

Kerri Scolardi participated on one ice dive in Lawrence Channel behind Wyatt Island. No krill or ctenophores, a potential major predator of small krill, were observed at the undersurface of the ice, even though both were collected in net tows in nearby areas. Two samples from the ice-water interface and one piece of golden-colored ice were collected and measured for chlorophyll and particulate organic carbon.

 

At the off-shelf station, acoustic backscattering layers were generally about 140 to 280 m deep. High winds and a large swell prevented much acoustic data collection. Larval E. superba were collected by some net tows at this station, but they had a very patchy distribution compared to that observed last year. Larval stages included Calyptopis 2 and 3 and Furcilia 1 and 2, whereas last year we found these stages as well as older furcilia. Few large E. superba were collected.

 

To date we have completed 1 lipid biomarker and an HPLC feeding experiment for krill in collaboration with Se-Jong Ju, 3 growth and molting rate experiments, 3 ingestion rate, 4 egestion rate, and 1 assimilation efficiency experiment for different stages of E. superba. We have collected 2-3 samples per day from the flow-through fluorometer to help characterize the along-track surface chlorophyll concentrations. In addition, Maureen Hodgins has collected chlorophyll profiles for all the CTD casts.

 

4. BG-237 Krill Biochemistry - Harvey - report by Se-Jong Ju

 

Our field team consists of Se-Jong Ju and Susan Klosterhaus. The major focus of this project is the biochemical determination of age structure in E. superba and lipid biomarkers indicative of its dietary history. A tucker trawl tow on 4/16 in Crystal Sound collected lots of adult krill by Dr. Torress group. Different size classes of adult E. superba (n=400) were sorted providing an adequate number (>300) for statistic analysis. After morphological measurements (length, eye diameter) were taken using a dissection microscope, eye tissues were carefully excised. Age markers (lipofuscins) were extracted from eye tissues and immediately analyzed to minimize potential problems of preservation and sample handling using the onboard HPLC system. Whole bodies were immediately frozen in the deep freezer for lipid analysis. A week later (4/20), the second set of adult krill (n=300) was collected on Process site # 5 using a tucker trawl. Morphological measurements and eye tissue collections were conducted immediately as described above. However, age markers (lipofuscins) from the second set of samples could not be analyzed immediately due to the sea condition on process site #1. After coming back to the near-shore site, those are being analyzed.

 

Additionally, the portable HPLC system for this project presented the opportunity for separation and analysis of algae pigment distributions in the water column. Water samples from CTD casts and brown ice (potentially ice algae) have been collected and will be analyzed on-board for algae pigments to provide information on phytoplankton distributions and communities in the water column and in the ice.

 

5. BG 239 - Cetacean ecology - Hildebrand - report by Ari Friedlander

 

14 April 2002

Day 8

0805 began observations as we steamed along the east side of Lavoiseur Island looking for seals to tag. Patches of fog and snow fog, visibility between 1-2nm, winds from the south began the day around 20-25 knots and diminished to 10-15 later in the morning. Position at beginning of watch: 66 10S, 66 29W. Stopped at 1000 for seal work and remained in that area for the rest of the day. Position at 1000 66 20S, 66 46W. No whales were seen, only 4 seals on scattered floes. Zodiac trip was attempted but stopped due to bad motor.

15 April 2002

Day 9

0800 ship transiting across Crystal Sound from east to west. Skies were mostly cloudy, BSS 2, 2/10 ice coverage of brash and bergy bits, and visibility was good. Position 66 45S, 66 44W. At 0805 4 minkes were sighted working a zone of open water between larger areas of ice. Zodiacs were deployed for seal tagging and whale biopsy. No biopsy samples were collected. The whales were seen once from the water and then were not seen again. Stayed out on ice to help with seal tagging and returned to the ship at 1500. When the ship began moving again, the minkes were resighted and the ship soon stopped for penguin capture, finishing off the daylight hours. Position at penguin capture at 1650, 66 42S, 66 57W.

 

16 April 2002

Day 10

Position at 0755 66 30S, 67 34W. Snow fog, 0.75 nm visibility, in 8/10 brash and bergy bits. At beginning of effort, 3 minkes were seen in the open lee of a small berg. Ship stopped at 0845 for seal capture and resumed steaming at 1345. Ice loosened to 5/10. A single humpback whale was sighted at 1400 in 3/10 ice nearing open water. At 1540 the ship stopped for penguin capture at 66 44S, 67 09W.

 

17 April 2002

Day 11

0800 towing mocness nets in Crystal Sound. Winds were 15-20 knots, skies partly cloudy, visibility was good. Some bergs and floes in the area. At 0850, 2 minkes were seen at 66 39S, 67 25W. Ship then stopped for seal capture for the rest of the daylight. However, when leaving the ship, a single minke whale followed the zodiac at close range and stayed with us to the ice floe with seals. The whale surfaced several times very close by, spy-hoped, swam under the zodiac right side up and upside down, and was generally very curious.

 

18 April 2002

Day 12

0800 ship stationed off Avian Island to drop of penguin team at 67 46S, 68 51W. Remained off Avian moving the team on until 1425 when we began a slow ADCP/HTI survey across the northern end of Marguerite Bay and heading generally north. Skies were partly cloudy, with excellent visibility. Winds were light in the lee of the island, but increased to 20 knots once into the bay. No whales were seen at the time that observations ended at 1630 at 67 57S, 68 36W.

 

19 April 2002

Day 13

0815 position 67 41S, 68 15W. Skies were partly cloudy, BSS1-2, visibility excellent at 3nm. Ice to the north as small cakes and floes and bergs. Continued throughout the day on a slow (4knots) acoustic survey of Labeuf Fiord area weaving east to west and heading from south to north. No animals were seen until 1600. At that time, several crabeater seals were seen, as were a dozen or so Adlies on floes. A group of 12 orcas was sighted meandering through 6/10 pack ice and bergs. There were 2 large males in the group, as well as at least 2 other large animals, and one distinctly small calf. The orcas passed the beam at 1km from the ship and some video was taken. They appeared to see the ship, as evidenced by several high surfacings, but did not alter their course of travel. Observations ended soon thereafter due to failing light. A sonobuoy was deployed at 1642 and listened until 1753, but no sounds were heard.

 

20 April 2002

Day 14

Observations began at 0755 at 67 17S, 67 50W under cloudy skies, BSS 1, good visibility, and fine sighting conditions. We circled around Day and the Wyatt Island searching for seals. Some bands of ice were encountered, but mostly there was open water, newly frozen grease ice and glacier rubble in some spots. We stopped at 1005 for seal capture and remained there for the rest of the day, diving afterwards. No whales were seen before stopping.

 

21 April 2002

Day 15

At 0845, 67 37S 67 57W, winds were high (30-40 knots), skies were overcast and visibility was 1nm. The ship was doing an ADCP survey back and forth on the same line at the south end of Laubeuf Fjord. No survey effort due to winds and continuous survey of the same area. Incidentally, nothing sighted.

 

22 April 2002

Day 16

Survey effort began at 0805 during an ADCP survey at 67 57S, 68 30W. Skies were overcast ,visibility was good and BSS 3-4. No sightings were made by 0945 when we stopped to mocness tow.

 

23 April 2002

Day 17

0925 position 67 51S, 67 58W after rendezvous with NBP, skies were clearing, BSS 2-3, visibility was good, began steaming around Adelaide Island towards the offshore station. Between 67 36S 69 22W and 67 32S 69 24W (Johnston Passage) ice was 3/10 brash bits in neat lines, 3 sightings of humpback whales (2 mom/calf pairs and a single animal) and over 300 crabeater seals were seen. The crabeaters were mainly in large groups of 20-50 animals in the water, but at least 50 were hauled out on small floes.

 

24 April 2002

Day 18

0825 position 66 08S, 71 23W, BSS5 skies overcast visibility 1 nm, no ice. Effort continued until 1130 for a deep CTD cast. At this position at 1330 a pair of large humpback whales surfaced near the ship and remained social for 5 minutes before diving and then reappearing near the ship (50 meters). Position of sighting 66 10.49S, 71 19.82W.

 

25 April 2002

Day 19

0800 MOCNESS tow in progress, followed by a CTD cast. BSS 5, skies cloudy, visibility 1.5 nm. No observations made today.

 

26 April 2002

Day 20

0900 position: 66 12S, 71 17W. Conducting ADCP survey, BSS 6, snow and fog, poor visibility. No observations made until 1345 at 6610S, 71 03W, for 2 hours. No sightings were made.

 

27 April 2002

Day 21

0845 position: 66 13S, 71 18W. Day spent at station or doing tows. No survey effort, and no sightings.

 

28 April 2002

Day 22

0840 position: 67 32S, 70 00W. Winds 25-30 knots, overcast and foggy skies, steaming to Avian Island around Adelaide. No survey effort, only incidental watch kept. No sightings made.

 

Survey Times and Sightings Log, 14-28 April 2002

 

Date

Start Survey

Finish Survey

Survey Time

 

11-Apr

11:50

13:56

2:06

 

11-Apr

14:39

18:17

3:38

 

13-Apr

17:19

20:47

3:28

 

14-Apr

12:02

13:47

1:45

 

15-Apr

11:51

13:58

2:07

 

16-Apr

17:43

19:35

1:52

 

17-Apr

14:36

14:53

0:17

 

18-Apr

18:24

20:31

2:07

 

19-Apr

12:07

16:23

4:16

 

19-Apr

17:33

20:33

3:00

 

20-Apr

11:49

14:06

2:17

 

21-Apr

12:02

13:43

1:41

 

22-Apr

13:21

20:13

6:52

 

24-Apr

12:22

15:31

3:09

 

26-Apr

17:40

19:27

1:47

 

28-Apr

14:22

15:31

1:09

 

28-Apr

18:31

20:08

1:37

 

TOTAL

 

 

42 Hours 8 Minutes

AVERAGE

 

 

3 hours/day

 

 

 

 

 

 

 

 

 

sighting #

species

number

date

18

minke

4

15-Apr

19

minke

3

16-Apr

20

humpback

1

16-Apr

21

minke

2

17-Apr

22

orca

12

19-Apr

23

humpback

2

23-Apr

24

humpback

2

23-Apr

25

humpback

1

23-Apr

 

 

 

 

TOTAL

8 sightings of 27 animals

 

3 sightings of 9 minke whales

 

4 sightings of 6 humpback whales

 

1 sighting of 12 orcas

 

 

 

6. BG 245 - Krill and fish ecology, krill physiology - Torres

 

Process station 7. The bottom topography at process station 7 was shoal and necessitated our taking very shallow tows to assure the safety of our nets. MOC 10 tows were limited to maximum depths of 300 m and were taken in the Matha Strait. We captured very large quantities (2-3 l) of large (45-50 mm) krill in the upper 100 m. Oceanic fishes, notably Electrona antarctica and Gymnoscopelus nicholsi, were captured in both MOC 10 and Tucker trawl samples. Sixty individual determinations of metabolism and excretion on a variety of species were completed. Species included: E. superba, Calanoides acutus, Metridia gerlachei, and Pareuchaeta sp.

 

Process station 5. Laubeuf Fjord and its adjoining fjords on the east contain several depressions of 800 m or more. We were able to deploy our MOC 10 with a margin of safety in two depressions that run along the axis of the fjord, and captured a similar fauna in each. Five MOC 10 tows and ten Tucker trawls were completed at station 5. In addition, 2 dives looking for krill larvae underneath sea ice were completed in collaboration with the Daly program. Typical catches for the MOC 10 were as follows. Species are named in order of abundance. Species lists are incomplete.

 

 

Night

 

0-50 m Euphausia superba juveniles (<30 mm), Eusirus spp., Callianira, Thimble jellies

 

50-100 m Euphausia superba adults (>50 mm), Pleuragramma year class 2, Eusirus spp, Stygiomedusa gigantea

 

100-200 m Pleuragramma year class 2, E. superba adults, Eusirus, Antarctomysis ohlinii

 

200-300 m Antarctomysis ohlinii, Pleuragramma year class 2, Paraliparus terraenovae

 

300-500 m Antarctomysis ohlinii, thimble jellies , Electrona antarctica, Melanostigma gelatinosum

 

Day

 

0-50 m Themisto gaudichaudi, Eusirus spp, Antarctomysis

 

50-85 m Euphausia superba juveniles (<30 mm), Pleuragramma year class 2

 

85-125 m Euphausia superba juveniles and adults , Callianira, Pleuragramma

 

125-200 m Euphausia superba adults, Callianira, Eusirus

 

200-500 m Euphausia superba adults, Antarctomysis ohlinii, Eusirus, Electrona antarctica, Pleuragramma, Stygiomedusa gigantea

 

In addition to the trawling program, one hundred fifty individual determinations of metabolism and excretion were successfully completed on E. superba and a variety of other species at station 5. The character of the trawls differed from our 2001 cruise in the presence of large quantities of juvenile krill and Pleuragramma year class 2. Very few Pleuragramma were captured in 2001, and almost no juvenile krill. The oceanic fish Electrona antarctica was present in all trawls.

 

Station 1. Station 1 was at the shelf break in the vicinity of survey station 12 which allowed us to complete several tows to 1000 m of depth, giving us a good look at the full complement of oceanic fauna we were able to capture in our nets. We divided the station into two elements, one off the shelf in oceanic depths (station 1a-3000 m) and one just over the shelf break (1b - 500 m) The western Antarctic Peninsula shelf is atypical of Antarctic coastal regions in the absence of very cold (-2.0C) ice shelf water, which is potentially lethal to fishes without antifreezes. Even so, there is the potential for depth limitation of oceanic species with a range over the upper 1000 m of water. Our deep oceanic tows gave us a barometer for what was typically an oceanic species, what species were present only on the shelf, and what species were found in both areas. Typical catches for station 1a are described below with species listed in order of abundance. Species lists are incomplete.

 

 

 

Night

 

0-50 m Salpa thompsoni, Themisto gaudichaudi

 

50-100 m Salpa thompsoni, Euphausia triacantha, Electrona antarctica, Gymnoscopelus nicholsi

 

100-200 m Euphausia triacantha, Electrona antarctica, Gymnoscopelus braueri

 

200-500 m Euphausia triacantha, Thysanoessa macrura, Electrona antarctica, Protomyctophum bolini, Pasiphaea scotiae

 

500-1000 m Gennadas valens, Atolla atolla, Cyanomacrurus piriei, Cyclothone spp, Euphausia triacantha, Periphylla wyvillei, Parandania boecki, Euphausia superba

 

Day

 

0-50 m Themisto gaudichaudi

 

50-100 m Themisto gaudichaudi

 

100-200 m Callianira, Myctophid (unidentified)

 

200-500 m Euphausia triacantha, Protomyctophum bolini, Periphylla wyvillei, Cyclothone spp.

 

500-1000 m Electrona antarctica, Gennadas valens, Gigantocypris mulleri, Benthalbella elongata

 

There is clearly good evidence for diel vertical migration in the fishes at station 1. Euphausia superba adults were nearly absent, but our Tucker trawl picked up large numbers of larvae. Ninety individual measurements of metabolism and excretion on a variety of species were completed at station 1. Blood samples were taken from all species of fishes for hematocrit and total hemoglobin determinations.

 

7. BG 248 - Krill ecology, behavior, and modeling - Zhou

 

Prior to April 14

 

Our group is responsible for the 1-m Multiple Opening and Closing Net and Environmental Sampling System (MOC-1), Optical Plankton Counter (OPC) and Acoustic Doppler Current Profiler (ADCP) during the cruise. Both MOC-1 and OPC were tested prior to departure using a test cable. The sea cable termination was not done till we arrived at the Palmer Station. We had to increase the FSK signal voltage of the OPC when the sea cable was used. The FSK voltage was lowered down to 0.5v during the last winter cruise on the R/V Palmer. The resistance of the sea cable on the R/V Gould is much higher. The final voltage setting was set at 1.5 v (The standard is 3 v.). Both MOCNESS and OPC were working properly. The ADCP was set by Eric Firing at the University of Hawaii. The only difference in ADCP settings between last year and this year is that the pulse length is set to be 8 m instead of the 16 m used in last years cruise. The current ADCP data can be accessed in real time, which gives us a powerful tool to display the echo intensity measurements at real time.

 

Crystal Sound (April 14-17, 2002)

 

Our first station was in Crystal Sound. An ADCP survey and 6 CTD casts were conducted crossing Matha Strait, and the two channels between Crystal Sound and Hanusse Bay during the night of April 14 after seal and penguin operations during the day. The objectives were to understand the circulation patterns and krill distribution in this area. The ADCP current measurements show a mesoscale circulation pattern of 5-10 km, in general a clockwise circulation pattern in the southern part of Crystal Sound. The water near surface is fresher in nearshore regions and in Hanusse Bay. Most of the krill swarms were concentrated near Cape Mascart, the southern entrance to Crystal Sound, north of Liard Island. The ADCP transect to the east showed that there are still a fair amount of krill inside the Sound.

 

During the second night, we tried to make our way to Hanusse Bay through the channel between Adelaide Island and Liard Island. We had to turn around at 66 48.5S due to heavy ice. Very high abundances of krill were measured by ADCP during the transit. The study of krill distribution in Hanusse Bay was aborted due to ice.

 

Two MONESS tows confirmed the acoustic measurements of krill swarms, which are contributed mostly by Euphausia superba adults. The echo intensity in the swarms reached -60db. If we take the target strength of an adult krill as approximately -80db, the abundance of krill reached 100s individuals/m3.

 

A study of diel vertical migration was conducted using both ADCP and MOCNESS. Miles long krill swarms were found within the top 150 m during the night. In the morning transition period, they form smaller dense patches of 100s m and descend to 200-280 m. At depth, they again form a miles long dense swarm.

 

Laubeuf Fjord (April 18-23, 2002)

We started our acoustic and XCTD survey as soon as we dropped the penguin group on Avian Island on the 18th of April. The survey consisted of 8 longitudinal transects and 9 latitudinal transects covering from lower to upper Laubeuf Fjord. At each longitudinal transect, 3 XCTD were launched at the beginning, middle and end. The reason we used XCTDs instead of a regular Rosette CTD was to simply save time. Our operation was scheduled at night. We arrived at Hinks Channel in the morning for the seal and whale operation.

 

The survey indicated the zooplankton distribution is very much different from that of last year. We did not find the super swarms in the deep canyon at the lower Laubeuf. The distribution was more dispersed and relatively uniform in space. We found two layers at night: One from the surface to 50m contributed mostly by krill, and the second layer between 80 and 120 m contributed by fish larvae. The night and day MOCNESS tows indicated the top layer is contributed by intermediate-size krill. They migrated to 150-200 m during the day.

 

One MOC 01 tow was conducted in Cole Channel, and two were conducted in the Laubeuf deep Canyon. Comparing to last year samples, which indicated the dominance of adult E. superba in this area, E. superba does not dominate the samples collected in this year. There are mysids, amphipods, copepods, a lot of fish larvae and a lot of jelly fish.

 

The circulation study shows several clockwise and anticlockwise circulation features in Laubeuf Fjord. They seem to be associated with bottom topographic features. We took a 13 hour time series of velocity measurements over a transect to see the tidal period dynamics and vertical migration behavior of krill. The measurements showed the existence of a very weak tidal component up to several cm/s. The other component is up to 10 cm/s.

 

Shelf break Station (April 24-27, 2002)

We arrive at the station at 0100 am. The wind was at 35 knots from north northeast, occasionally reaching 50. Waves were washing over the main deck. MOC-1 tow was postponed to 0300am when the wind declined to 15 knots. During this period, a small scale ADCP survey was done to seek hot spots of back scattering. At the retrieving, the wind increased to 25 knots with 10 foot swells. Though the MOC-1 was deployed at the side of the A frame which caused a lot of difficulties during retrieval, it came back in safely despite the rolling and pitching.

 

MOCNESS samples at the off-shelf site revealed extremely high abundances of krill larvae, phytoplankton and salps in the top 50 meters. A deep layer was found at 150-200 meters. Some small fish were found in the net corresponding to that depth. In contrast with the samples from the off-shelf site, samples at the on-shelf site show no or very few krill larvae. Phytoplankton was still found n the top 50 meters.

 

Two ADCP surveys over the off-shelf and on-shelf regions were carried out during the periods when other activities were cancelled due to weather. The circulation shows that our off-shelf site was set in a counter clockwise small eddy, and our on-shelf site was in a region where the current crossed the shelf break onto the shelf. Large amount of krill larvae were found in net tows prior the wind storms at the off-shore site. After the storm, krill larvae were not found on both off-shelf and on-shelf sites. If we assume that the wind-driven Ekman layer is down to 50 meters, within which krill larvae were found, the transport of krill larvae should be in the on-shore direction because of the predominant north northeast wind.

 

8. Nutrient analyses - Morin

 

 

Nutrient and O2 Analysis of CTD Bottle Samples

 

Oxygen profiles show a distinct reduction from the surface to a depth of between 200 and 300 meters. This downward trend generally lies below a relatively stable surface layer with high concentration (7.8-8.0 ml/L, approx 50 m) that is evident regardless of the existence of an obvious mixed layer defined by the salinity profiles. In the deep water stations the oxygen minimum has concentrations below those of the bottom waters. In many cases the concentration begins to increase at the O2 minimum and increases consistently to the bottom of the bottle cast.

The nutrient profiles thus far have shown remarkably similar trends. Expected surface water depletion in NO3- , HSiO3, and HPO4=, are evident in almost all profiles. The concentrations do not approach complete depletion, or levels approaching limitation. NH4+ and NO2- conversely show consistent increases toward the surface starting around the depth of the pycnocline. The depth of the origin of depletion in NO3-, HSiO3, and HPO4=, and the beginning in the increase in NH4+ and NO2- co-occur with the oxygen minimum. In many cases the depth of the minimum in oxygen concentration corresponds to a peak in both NO3- and phosphate. A localized subsurface peak in nitrite concentration is also evident in many of the profiles slightly above the oxygen minimum and above the depths of the peaks in NO3- and phosphate.

 

Nitrate and phosphate concentrations in the bottom waters of the deepest cast (Station 1, event 112, event 122) show extremely low variability below the pycnocline (NO3- standard deviation is 1.25% of mean for bottom 2500m, 12 samples, HPO4=, standard dev is 1.36%). HSiO3 displays a slight increasing trend with depth but also exhibits very low variability.