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

14 August 2002

The biological and physical work in the southern sector of the SO GLOBEC grid continued for a fourth day aboard the N.B. Palmer. It was a day that was particularly clear and brutally cold. Gale force winds in the 30 to 40 kt range and -16 C temperatures made work on deck miserable. The pack ice continued to be very tough to move through in some places and more easily traversed in others, especially where there were leads. The steaming between stations, nominally 20 nm apart, could take six or more hours. It was an eight hour struggle to get from station 81 to station 82, located on the outer continental shelf. In the late night of 13/14 August, in spite of the high winds, a 1-m MOCNESS tow was completed in a lead. This was followed by an ROV under-ice survey and an abbreviated ice collection station. The high winds blew freshly fallen snow up into the air causing near white-out conditions and forcing the pack ice sampling to be stopped after a short period. Pack ice drift of about a knot under the sustained winds brought us closer to Station 75 and helped shorten the steaming time there. In the early afternoon, a pair of CTD casts, one for micro-structure measurements and the other for more general water column properties, and a live animal collection with the Tucker trawl were completed there. Better ice conditions and continued pack ice drift allowed passage to station 74 further north along the outer shelf to be completed in about five hours. There another pair of CTD casts and a Tucker trawl was completed in the late evening. The Tucker trawl was done instead of a 10-m MOCNESS tow because the pack ice conditions for towing were judged to be marginal. Indeed, mid-way through the trawl, the towing cable was snagged by ice moving into the stern wake and before the ship could be stopped, the wire was strung out over the ice in the wake area some 50 to 100 m behind the ship. It took some time to clear the ice and bring the cable close enough to the stern to allow the net to be retrieved. Nevertheless, the catch provided planktonic animals for use in experimental studies on board the Palmer.

The weather provided both good and bad working conditions depending upon the scientific activity. For the seabird and marine mammal observers the clear skies and excellent visibility most of the day provided ideal viewing. The extreme cold made work on the deck difficult for everyone. The primary production incubators located on the helicopter deck proved particularly troublesome. The low temperatures caused pipes to break and sea water to flood a portion of the area late in the night. The MTs worked long hours to fix the incubators and to clear the area of slush and ice. Their efforts are very much appreciated.

The high winds first began about midnight on 13/14 August coinciding with a rapid drop in air temperature from around -2ºC to -10ºC. Winds out of the west southwest built rapidly into the 30 to 40 knot range and remained that strong for much of the day. The temperature dropped further and by 0732 was -16ºC. It remained there until late in the evening when it dropped down to -19.2ºC. By that time, the winds had subsided to the 8 to 12 kt range out of the southwest. The barometer stayed around 985 mb for a good portion of the day and only began to rise in the early evening reaching 994.3 mb by midnight. In spite of the cold and wind, it was bright and sunny. Before sunrise the first vestiges of day were evident on the horizon to the north as faint reds on a band of clouds. Overhead skies were dark and clear and stars were shining. The sun came up at 0945 as a bright orange ball that one could look at because of the filtering of the thin clouds on the horizon. The sky was clear for the most part and visibility was excellent. Large icebergs dotted the scene from morning to evening. There were also a number of long thin leads, which the Palmer used as passageways, and in which there were a number of seals and a few whales. The sun set about 1650 and it was a nice, but not spectacular sunset.

Sea Birds (Chris Ribic and Erik Chapman)

On August 13, surveys were conducted for almost four hours as the ship traveled between stations 81 and 82. These stations are south of Alexander Island and about 30 nautical miles offshore from Charcot Island. They are relatively far from the ice edge and the ice was around 1 m thick and covered 9 to 10/10ths of the ocean's surface. The ship struggled to move through this ice and we backed and rammed throughout most of the day. Once again no Adélie Penguins were observed, although two adult Emperor Penguins were in our transect, hauled out next to a lead. Snow Petrels were more abundant than in recent days and seemed to be regularly spaced as we moved down some several mile-long leads. Crabeater seals were abundant once again, and were mainly hauled out on the ice along leads. In general, Crabeater seals appear to be very abundant in the southern sector of the grid, offshore of Alexander Island.

A summary of the birds and marine mammals observed on 13 August (YD 225) during 3 hour 48 minutes of survey time as the ship traveled between stations 81 and 82 is the following:

Species (common name)	Species (scientific name)	Number observed
Snow Petrel	Pagedroma nivea	17
Emperor Penguin	Aptenodytes forsteri	2
Crabeater Seal	Lobodon carcinophagus	54

On August 14, surveys were conducted during 4 hours and 36 minutes as the ship traveled from station 82 to 75 and then on to 74. Sea ice covered about 9/10ths of the ocean surface. Here the ship was within 20 or 30 miles of the ice edge, much closer than it has been in several days. Snow Petrels were observed in small numbers within leads during the survey and a single Antarctic Petrel was seen. Antarctic Petrels are typically found in both open water and ice, but generally near the ice edge. The sighting today may have indicated the ship's proximity to the ice edge offshore. A Snow Petrel was observed feeding on fish from the surface of one of the leads. The bird landed on the water, dipped its bill just below the surface, and flew away with a 3 inch long narrow fish, possibly a juvenile ice-fish. The petrel then landed on the ice adjacent to the lead where it quickly swallowed the fish whole. Though we have seen Snow Petrels feeding, this was the first time we were able to identify the prey.

A single Adélie Penguin was observed near open water immediately adjacent to a large iceberg. A group of 6 Emperors, 4 adults and 2 juveniles, was also observed hauled out on the ice near the same iceberg. Though we have consistently seen small numbers of Emperors in this region, it appears that Adélies are quite rare in the pack ice in the southern portion of the study area.

Crabeater seals were again abundant today (14 August). However, it was interesting to note that although virtually all of the 54 seals observed yesterday were hauled out on the ice, all of the 27 observed today were in the water. Temperatures yesterday were around 2ºC, with a wind chill near 10ºC. Today the temperatures had dropped to 16ºC with winds of nearly 30 knots dropping the wind chill below 40ºC. The seals may have been avoiding the severe cold air temperatures by remaining in the “warm” 1.8ºC sea water.

A summary of the birds and marine mammals observed on 14 August (YD 226) during 2 hours 21 minutes of survey time as the ship traveled between stations 82 and 75, and 2 hours 15 minutes between station 75 and 74 is the following:

Species (common name)	Species (scientific name)	Number observed
Snow Petrel	Pagedroma nivea	11
Antarctic Petrel	Thalassoica antarctica	1
Emperor Penguin	Aptenodytes forsteri	6
Adélie Penguin	Pygoscelis Adelii	1
Crabeater Seal	Lobodon carcinophagus	27

Marine Mammal report (Chico Viddi)

Today (14 August), the sky let us see its blue color with a different and wonderful sunrise. The sun brought us light, but not warmth, since the air temperature was -17ºC and wind chill was -45ºC. Floes of first year ice, about 70-90 cm thick, characterized the survey area as we steamed to stations 82, 75, and 74. The ice ranged from 9 to 10/10ths coverage, with some long and narrow leads of open water. Weather was optimal for viewing, even though wind speeds were between 25 to 35 kts, with gusts up to 40 kts. Marine mammal observations were made for 8.1 hours of which 4.38 hours corresponded to effective effort hours and 3.72 hours to incidental observation. It was an extremely good day for the cetacean survey. There were four sightings of minke whales (Balaenoptera acutorostrata) with a total count of 8 different whales. The first sighting was at 0950 at 1.3 nm and at 8º to starboard (-68º 40.34′S; -76º 32.06′W). This whale swam ahead of the ship in a lead 100-150 m wide for at least ten minutes and disappeared from view just before the Palmer entered the ice pack again. At 1135, we stopped at station 75 (-68º 32.32′S; -76º 18.62′W), where the second sighting took place. Four minke whales were first observed at 1145, 1.7 nm and at 150º to port. These whales were observed for more than three hours in the same area. During the first two hours, the whales were surfacing in an area of probably less than 5 square nm. In the next hour, the whales were observed moving north and disappeared at 1439. We left station 75 at 1503 to steam to station 74 and at 1602, two minke whales were sighted at 1.26 nm and 90º to port (-68º 24.08′S; -76º 08.33′W). Finally, at 1634, a single minke was seen at 0.2 nm and 78º to port. This whale was sighted several times until the last blow was seen at 1708.

The first whale sighting made today was just a few miles away from the sightings made on 11 August. This was an interesting and important observation since this likely means that there is sufficient food to attract whales and enable them to stay in the area for foraging proposes. It is not known if these were the same whales seen three days ago. More than 30 Crabeater seals (Lobodon carcinophagus) were seen today, the first group (15 seals) was seen at 0905 (-68º 43.197′S; -76º 38.862′W) and the last group seen was at 1553 (-68º 24.67′S; 76º 10.35′W). All crabeater seals observed today were in the water. No seal was seen on ice, which makes these sightings very different from past observations. There may be more than one explanation for this event: today's air temperature was very low, making it warmer for seals to stay in the water and not on ice; as observed with whales, this area might be of great importance in terms of food resources, and therefore seals were spending most of their time foraging; and finally, it may have been mere coincidence.

Krill Physiology and Fish Ecology (Jose Torres, Tom Bailey, Joe Donnelly, Melanie Parker)

A Tale of Two MOC 10'S

The fish ecology/krill physiology team has now completed two successful MOC 10 tows. The MOC 10 is “verbal shorthand” for a Multiple Opening and Closing Net and Environmental Sensing System or, using the underlined letters to form an acronym, MOCNESS. The opening at the mouth, or front end, of the net is 10 square meters, a square about 3 meters or 10 feet on a side. It is a large net system; you could easily fit a Volkswagen bug inside it. The great thing about it is that we have six nets on the same frame, so that each time we use it, we can sample at six different depths. In the old days, we would have had to do six separate tows to get the same information we now get in one! In addition to that, we have special sensors on the net frame that tell us how deep the net is fishing, what temperature the water is, how salty the water is and how much water is flowing through the net.

We were able to sample in Crystal Sound at the northern end of our study area and then much farther south, at a latitude of -68º 30′S. We found a big difference between the two places in the amount of marine life, and to some extent, the species that were present. In Crystal Sound we caught a lot more krill and fishes. As you probably know by now, Crystal Sound is a very rich area with a lot of seals and penguins that hang out there. You might expect to find a lot of seal and penguin food, that is, krill and fishes, and that is just what we did. We got some species there that are found out in the open ocean, but also some that are only found right near the coast, a pretty rich mixture. In contrast, our tow down south gave us only oceanic species, and fewer of them. We caught no fish! We are going to do another tow today (14 August), and will let you know if we see a big contrast between the three sites.

Another characteristic of the Antarctic marine life we are studying is whether they change their depth with time of day. A lot of fishes and shrimp in the ocean migrate vertically at dusk and dawn, going up to near the surface at dusk, usually to feed, and back down to deeper waters at dawn. We would like to see whether krill and other Antarctic marine species do this as well. So far it looks like they do. Our MOC 10 net is the ideal tool for studying vertical migration because of its multiple nets. We will report more of our results a little later in the cruise.

ROV report (Scott Gallager, Phil Alatalo)

Station 82. This station was characterized by thick ice, high ridges, and small compacted floes. The wind was hovering around 35-40 kts in near whiteout conditions as the ROV was deployed off the starboard quarter at 0509. Deployment of the ice team was delayed due to the wind conditions. The ROV had been sitting on deck waiting for the crane operator for half an hour and had reached the ambient temperature of -20ºC. When the ROV hit the water a spray of newly formed ice exploded off the metal parts into a convective plume billowing up from the vehicle. A thick layer of ice immediately formed on the stereo camera windows causing a blackout on the control monitors. Since we had not as yet pulled the release pin, we were able to bring the ROV up to the level of the gunwale and spray the windows with alcohol and a soap solution. The alcohol lowered the melting temperature while the surfactant in the soap did not allow new crystal to form on the glass surfaces. The ROV was put back in the water and released with a few minutes. A crabeater seal played in the vicinity of the ROV during the entire deployment frolicking in intense light of the strobe. Unfortunately, this was the only organism observed during this deployment. Not a single furcilia, ctenophore, fish larva, or isopod.

MOCNESS/ADCP/OPC Report (Phil Alatalo, Ryan Dorland, Peter Wiebe, Dicky Allison, Ryan Dorland, Scott Gallager, Gareth Lawson)

Expert piloting, clever fishing, and exactly enough open water resulted in a successful MOCNESS Tow #3, early in the morning on 14 August. Nearing Station 82, the ship battled thick ice, snow, 30 kt winds, and gusts over 50 kt, until suddenly a short 1.5 nm lead appeared. Although the lead was not long enough to warrant a tow deep enough to profile the shelf break, the ADCP showed a heavy scattering layer between 125 and 75 m. The winds subsided slightly and the lead remained open long enough to fish the MOCNESS down to 260 m and back, albeit with reduced water volume filtered Below 200 m, copepods dominated the catch, along with small chaetognaths, ostracods, and some furcilia. A beautiful, orange siphonophore was present in Net 1. Krill dominated the depth strata from 150 m to 50 m, with the greatest concentration between 75-50 m. Biomass dropped off dramatically above 50 m; small krill, furcilia, and copepods composed the makeup of nets 7 and 8. From ADCP data, the MOCNESS nets appear to have just caught the southern edge of the patch. The patch continued along our cruise track to the northeast for approximately one nautical mile after the tow. Little data were collected by the OPC unit, which was turned off at the bottom of the tow in an attempt to troubleshoot a persistent communication problem between the MOCNESS deck unit and the underwater unit. ADCP Current measurements were sporadic during station 82; during the tow the currents were predominately north-northeast between 10 and 15 cm/s.

Current Position and Conditions

We are currently working in a large lead some distance from Station 72. We were unable to get to that location due to very tough ice conditions and time constraints. Our position at 0037 on 15 August was -68º 34.696′S; -74º 06.606′W. Air temperature was -7.0ºC and the barometric pressure was 1002.1 mb and rising slowly. Winds were out of 234º (southwest) at about 8 kts. The moon was barely showing through high clouds, but visibility was good.

Cheers, Peter