Report of Activities on the RVIB N.B. Palmer Cruise 02-04

8 September 2002


The weather along the Western Antarctic Peninsula is certainly changeable. Whereas yesterday we were enveloped in a dense fog, on 8 September we woke to mostly clear skies and a very nice sunrise.  A high thin cloud layer filtered the sunlight and softened the reflections off the snow and ice covered peaks of Adelaide Island, which loomed large as we worked our way north along the island's shore.  The massive Fuchs Ice Piedmont leading down to the abrupt ice cliffs at water's edge never fails to inspire awe.  A fringe of wispy clouds sat at the base of the Piedmont. For much of the day there was essentially no pack ice, just mostly frozen surface of the large polynya that we entered yesterday.


During the day, work was completed at stations 19, 18, and 17.  At station 19, the remaining task that finished off the station was a 1-m MOCNESS tow taken in Johnston Passage between midnight and 0230.  BIOMAPER-II was then towyoed to station 18 arriving about 0930.  Just before arriving at station 18, the smell of smoke was reported from the aquarium room and shortly thereafter the fire alarm sounded. There was a localized fire in a scrap wood pile in the aft cargo hold of undetermined origin. It was quickly extinguished by the safety crew. The scientific party was also very quick to respond and inside of two or three minutes all were accounted for in the muster area on the 03 level. Within an hour, work began again with the deployment of the CTD.  The BIOMAPER-II was positioned about 12 m below the surface during the pair of CTD casts so that time-series acoustics data could be compared with the microstructure in the water column. By noon, the Palmer was underway headed for station 17 only 11 nm away. This transit took us back into a region of pack ice, which was composed of large broken floes, brash ice, and open water leads. A low swell was running through the area, helping to keep the floes from cementing together and making it easier to traverse.  


There was, however, a problem that developed with the CTD at the end of the cast at station 18.  Strands of the outer armor of the CTD conducting cable had broken during the cast about 5 meters above the cable termination.  Re-termination of the cable was started on the way to station 17 and was completed more than seven hours later in time to deploy the CTD as the last event at that station.  An under-ice SCUBA dive led off the work at station 17 in the late afternoon.  The nature of the pack ice and winds were such that the ice collection preceded the ROV deployment instead of both being done at the same time. The ROV deployment was cut short because a thruster developed problems and the ROV could not be maneuvered well enough to counteract the ship and pack ice drift.  The deployment of the pair of 1-m ring nets off the stern netted a good catch of krill and copepods for experimental work just before the CTD cast was done. Work at station 17 was finished just after midnight and BIOMAPER-II was again deployed for the steam to station 9.   


Working conditions during 8 September remained good for the most part. The winds were in the 25 to 30 kt range out of the southwest during the MOCNESS tows at station 19, but had no effect on them. By early morning, they had dropped quickly to 10-12 kts or less along with a corresponding shift in direction to east-northeast. They remained in that range until increasing again to 20 kts in the evening. The changes in wind speed and direction correlated with a shift in barometric pressure which dropped from 1012 to 1008 mb until 0600 and then began to rise again.  Air temperature varied between -7 and -3ºC. 


CTD Group report (Baris Salihoglu, Eileen Hofmann, Bob Beardsley, Chris MacKay, Francisco (Chico) Viddi, Sue Beardsley)

During September 8, we completed two inner stations on transect 3. Around noon, two CTD casts were made at station 18 for CMiPS sampling and to sample the water column to the bottom.  The second cast also included FRRF sampling.


During the last cast at station 18 the CTD cable frayed due to rust and wear. After this station 300 m of the CTD cable was cut off and the cable was mechanically and electronically re-terminated. After the re-termination processes were done, the cable was pull tested for 15 minutes under 3000 lbs of pressure and made ready for the following cast. Many thanks to Marine Technician Stian Alesandrini and Electronics Technician Fred Stuart for their efforts.


Because the re-termination of the CTD cable was a time consuming process, the CTD cast which was scheduled first for station 17 moved to the late hours of September 8 and the results from this station will be included in the report for 9 September.


Station 18 was the innermost and the shallowest station on survey transect 3. Surface sea water temperatures at this location were above freezing at -1.79ºC with a salinity of 34.04. The mixed Winter Water layer extended to 80 m at this station.  The maximum temperature observed below 300 m was 1.4ºC with a corresponding salinity of 34.70.  This is an indication that Upper Circumpolar Deep Water (UCDW) that had been modified by mixing with the overlying Antarctic Surface Water and Winter Water extended to the shore.


The temperature and salinity sections plotted for transect 3 showed that the UCDW intruded onto the shelf below 200 m. Surface temperatures along this transect were at freezing (<-1.8ºC) at the outer stations and the salinity at these stations was lower (33.9) than that observed at the inner stations. This resulted in a downward tilt in isoclines towards the edge of the shelf.


The distribution of the temperature maximum below 200 m shows the southern boundary of the Antarctic Circumpolar Current (ACC), distinguished by the 1.6ºC isotherm flowing along the outer boundary of the continental shelf. The southern boundary of the ACC curls towards the shelf at the central and northern parts of the study region and this coincides with UCDW intrusions. The UCDW makes one intrusion onto the shelf towards Marguerite Bay in the central study region (as described in 27 August report) and another one in the northern part of the study region along Marguerite Trough and onto the shelf.


A similar pattern was observed during the previous NBP02-02 cruise and also during the two U.S. SO GLOBEC cruises that took place last year (NBP01-03 and NBP01-04). This suggests that intrusions by UCDW may be permanent features on the west Antarctic Peninsula continental shelf.


As reported in the summary of CTD activities for 7 September, the fourth set of CMiPS time-series casts was made at station 20A in a large lead in dense fog in the center of Marguerite Trough.  The Palmer had been following leads towards station 20 from 21 over the outer shelf, and the location of 20 was moved to 20A to stay within the lead and over the deepest part of the trough. The Palmer stopped at the side of the lead, which was covered by nilas with ice flowers in some regions and some open water. The lead was roughly 2.5 nm long and 0.3 nm wide, with the ship located in the center lengthwise.  When doing the first CMiPS cast to 350 m, we noticed that the base of the surface layer was very sharp, so we did a second CMiPS cast to 350 m. While doing this, Peter Wiebe reported that BIOMAPER-II was showing a distinct scattering layer at about the base of the surface layer that appeared to have physical and not biological origins, perhaps due to concentrated sound speed gradients. We then made a third CMiPS cast between 50 m and 150 m, then made the last CTD cast using the FRRF lowering speed of 10 m/min for the first 50 m, then 20 m/min to about 110 m (below the base of the surface layer), then the CMiPS speed of 40m/min to the bottom.  The CTD and CMiPS data from these casts look excellent and will provide a good representation of microstructure variability in an active polynya region.


Phytoplankton Ecology / Primary Production (Kari Sines and Frank Stewart)

Week five of sampling (1 September to 8 September) for the primary production group was the start of the water collection in the northern sector of the SO GLOBEC survey grid.  Eight more simulated in situ (SIS) experiments were completed at stations 4, 2, 13, 10, 15, 23, 21, and 19 showing higher production in this area (a maximum of 7.2 mgC/m2 in the northern grid compared to a maximum of 3.3 mgC/m2 in the other grid sections).  The FRRF was deployed as part of the CTD/rosette in nine of the seventeen CTD locations.


Chlorophyll continued to be sampled at twelve depths per CTD cast and results show a trend matching production, with higher chlorophyll in the north than in the south. In the northern sector chlorophyll a levels ranged from as low as 2.5 mgC/m2 to as high as 7.46 mgC/m2 (integrated to 100m).  Particulate carbon samples were also preserved at nine more stations during week five.


Seabirds (Chris Ribic and Erik Chapman)

Seabird and Crabeater seal surveys were conducted for almost five hours as the ship moved north approximately 10 miles offshore of Adelaide Island between stations 19, 18, and 17.  We traveled through a large, recently frozen lead immediately adjacent to the western shore of Adelaide Island and the primary ice-type was new gray in 7 to 10/10ths concentration for most of the survey.  As the ship began to move offshore, toward station 17, we encountered a distinctly different ice-habitat consisting of larger, first-year floes with extensive rafting and snow-cover in 7 to 10/10ths concentration.


Today's survey provided an opportunity to compare the biology associated with two distinct ice-types; new gray ice, and older first-year floes.  Few birds were observed in the new gray ice alongshore of Adelaide.  Snow Petrels, Kelp Gulls, Southern Giant Petrels, and Antarctic Petrels and Adélie Penguins were all observed, but in low numbers.  Seals were observed here, but also in low numbers before heading into the first-year floes on the way to station 17.  After moving into the older ice, Crabeater Seals and Snow Petrels were immediately more abundant.  Apparently, BIOMAPER II recorded a change in the prey-field at this point, with a noticeable increase in the amount of zooplankton under the older sea-ice.  Adélie Penguins were also observed here along with two Emperor Penguins.


A summary of the birds and marine mammals observed on 8 September (YD 251) during 2 hours 38 minutes of survey time as the ship moved between stations 19 and 18 and 2 hours 21 minutes as the ship traveled between 18 and 17 is the following:



Species (common name)

Species (scientific name)

Number observed           

Snow Petrel            

Pagodroma nivea                


Kelp Gull              

Laru dominicanus                


Southern Giant Petrel  

Macronectes giganteus          


Antarctic Petrel       

Thalassoica antarctica         


Adélie Penguin          

Pygoscelis adelii              


Emperor Penguin        

Aptenodytes forsteri            


Crabeater Seal         

Lobodon carcinophagus          




Marine Mammal report (Chico Viddi)


Spring is in the air and it can be smelled.  Sunrises are earlier and sunsets later, days are getting longer.  Since 1 September, 9.1 hours of observation and 4.9 of “effective effort” have been done on average per day.   On 6 September, 9.65 hours of observation were done of which 6.7 hours corresponded to “effective effort”.  The 6th was a beautiful sunny day, with great visibility and wide areas of open water and frozen leads. Seventeen Crabeater seals (Lobodon carcinophagus) were observed, 3 of them at 1130 and 14 between 1700 and 1715. Only one seal was seen in the water. These seals are not the only marine mammal in the area, a Minke whale was seen from the bridge at 1701 (-66º 52.91′S; -71º 16.32′W) by Erik Chapman.  It was seen surfacing only once while on transit to station 21.  On 7 September, 9.73 hours of observation were done in spite of a very dense fog which would not allow us to see further than 0.3 nm.  This affected the “effective effort” considerably and only 53 minutes were logged by the end of the day when cleared up enough for a cetacean survey.  Even though visibility was very low, 117 Crabeater seals were counted.  Three of them were seen during the early morning, while the rest were seen between 1430 and 1753.  Ninety-seven seals were observed in the water, in groups of 10 to 25 animals.  This large number of seals was seen in the same vicinity that BIOMAPER-II was recording substantial acoustic patches of animals (often krill) in the water column.


On 8 September after 40 days on board the N.B. Palmer, 280.2 hours of marine mammal observation have been logged. The “effective effort” hours have totaled 132.1 and during this time 38 sightings were made. After the cloudy and foggy day on the 7th, the 8th was again a day to see the beautiful snow-covered mountains and the massive glaciers of Adelaide Island. While steaming from station 19 to 18, the high peaks of Mt. Reeves, Bouvier, Mangin, Barre, Gaudry, and Liotard stood out during the orange-blue sunrise in the background. The day was absolutely gorgeous, even though there was a high thin cloudiness most of the day.  The big mountains and the wide polynya made the landscape look wonderful.


Visibility and weather conditions on 8 September were excellent for the marine mammal survey. Observation hours totaled 9.6, but only 4.2 were “effective effort” hours (due to time spent at stations 18 and 17). It was a very good day for marine mammal active counting. A spectacular number of 179 Crabeater seals (Lobodon carcinophagus) was obtained (the highest count yet of Crabeater seals), while three Minke whales (Balaenoptera acutorostrata) in two different sightings were also registered.


Only 7 seals were observed during the morning (between 0730 and 1130) and 172 were observed in the two hours of observations between 1230 and 1430, while steaming from station 17 to 18 (-67º 01.97′S; -69º 12.63′W and -66º 56.64′S; -69º 30.07′W, respectively). After almost two days of steaming through the very wide polynya, we left station 18 (around 1200) and got back into the ice pack where all 172 seals were seen. They were all hauled out on ice. The 7 seals seen during the morning were observed while in the polynya. It is important to note that this low number of seals counted could reflect the greater difficulty in seeing and counting seals when they are in the water.


Three Minke whales were observed in two different sightings. The first whale was seen at 0833 (-67º 06.30′S; -69º 14.85′W) while on transit to station 18. It was a single whale seen at 0.3 nm and 90º to starboard. The second sighting corresponded to two Minke whales seen at 1123 (-67º 02.88′S; -69º 08.62′W) and at 1.5 nm from the ship. This observation was made during the CTD cast at station 18.


Only a few krill patches were detected during early morning by the ADCP and BIOMAPER-II, but greater concentrations were observed during the afternoon, when the Crabeater seals were seen.


BIOMAPER-II group report (Gareth Lawson, Peter Wiebe, Scott Gallager, Phil Alatalo, Dicky Allison, Alec Scott)

Early in the morning of September 8 we towed the BIOMAPER II alongside Adelaide Island, from station 19 on broad-scale transect 4 to station 18 on transect 3. From the start of the tow at 0340 until 0630, a diffuse layer of backscatter was present between 50 and 150 m. The layer was most dense below the pycnocline (about 80 m), and frequently became intensified into dense patches 600 to 1250 m long. The towbody passed through the top of one of these patches and large krill were observed with the Video Plankton Recorder (VPR). At 0630 this layer began to descend deeper in the water column, and by 0845 had reached a depth of 350 m: a clear case of a diurnal vertical migration, occurring at a rate of 1.5 m/min. Throughout the tow, VPR observations were made from 35 to 90 m depth, and indicated the presence of copepods, diatoms, radiolarians, pteropods, and small krill. During most of the towyo, enhanced scattering and evidence of large individual targets were observed below 300 m. Just before we reached station 18, the bottom came within range of our transducers, and a dense bottom layer 80 m high was present.


At station 18 we kept the BIOMAPER II in the water while the CTD group conducted their casts. Thin layers of backscatter were less evident during these casts than yesterday, but we did still observe layers that may represent scattering due to the physical structure of the water column rather than scattering from planktonic organisms. As indicated in our last report, it will be very interesting to compare in detail the microstructure profiles recorded by the CTD with our profiles of backscatter.


At noon, we started along survey line 3, heading between stations 18 and 17. There was little suggestion of any shallow scattering layer, other than infrequent enhancements near the pycnocline at 60 to 70 m. On one occasion we intercepted one of these regions of enhanced scattering with the BIOMAPER II and observed krill and copepods with the VPR. Elsewhere in the 50 to 90 m depth range, we saw small copepods, diatoms, and radiolarians. Close to station 18, the bottom layer we observed as we arrived at the station was still present. Four large (36 to 77 m high, 370 to 900 m long) patches of backscatter approaching scattering intensities of -50 dB were observed between 200 and 300 m. We also saw a number of smaller patches of similar density in this depth range.


Current Position and Conditions

Station 5 on line 1 of the survey grid is the last grid station to be sampled on this cruise. We arrived at this station about 2130 on 9 September and work at the station should be completed around 0500 on the 10th.  Our current position at 0130 on 10 September is -66º 25.414′S; -68º 24.486′W.  The air temperature is -1.2ºC and the barometric pressure is 1006.1 mb.  Winds are around 25 kts out of the northeast (040). Skies are cloudy and snow has been falling steadily for the past several hours. The pack ice at station 15 is more solid than we have seen for the past several days, but still traversable without difficulty.


Cheers, Peter