R/V Polar Duke Farewell Tribute
in the Laboratory for Microbial Oceanography

First Winter Cruise of the R/V Polar Duke

August-September 1995
by Steven T. Kottmeier
Antarctic Support Associates

During the first contract year of the R/V Polar Duke, I was among a number of scientists, privileged to participate in its first Winter Cruise. The two overall objectives of this cruise, quickly planned by the Division of Polar Programs, National Science Foundation, were: (1) to test a variety of hypotheses in Antarctic marine science regarding functioning of the food web in late winter, and (2) to prove the late winter capabilities of the Duke, particularly with respect to accessing Palmer Station.

In regards to the first objective, the winter had been assumed by most scientists to be a season of low or no primary productivity due to low total downwelling irradiance due to extensive sea ice cover, low sun angle, and short day length, and low temperatures. Few, if any, actual measurements confirmed these assumptions. Very little was known about the winter survival and life histories of other species. For example, krill (Euphasia superba), a key species in Antarctic food webs, dependent upon phytoplankton for carbon and energy, were believed to adopt a variety of survival strategies to counter the assumed low winter productivity of phytoplankton. These included opportunistic feeding on lipid-rich copepods (Boyd et al. 1984), use of their exoskeleton as a source of energy (Ikeda and Dixon 1982), and sea ice algae (Hamner et al. 1983, Holm-Hansen and Huntley 1984, Boyd et al. 1984, and Garrison et al. 1986). This first winter cruise of the Duke provided an ideal opportunity to test a variety of hypotheses regarding the survival of krill and other species during the long "polar night."

In regards to the second objective, Palmer Station had been treated operationally like its more southerly sister stations of McMurdo and South Pole in having a true "winter over" population for the months. It was assumed that the station was inaccessible by existing vessels due to extensive sea ice cover in the Bellingshausen Sea surrounding Anvers Island. Hence it was this rare opportunity to be associated with "pushing the scientific and logistical envelopes" that I and many other scientists offered to participate in this historic cruise sponsored by the United States Antarctic Research Program (USARP). (Author's notes: The first winter cruise of the R/V Polar Duke was covered in an excellent article published in Smithsonian (Parfit 1986). The results of the research described here are detailed in Kottmeier and Sullivan (1987).)

Because of the accelerated schedule for fielding the cruise, the selection of the scientists for this cruise was restricted to principal investigators (PIs) who held existing grants from NSF/DPP. Of that population, only one PI decided to participate, Dr. Langdon Quetin, who by default became the Chief Scientist for the cruise. I was selected by my PI, Dr. Cornelius W. Sullivan (now Director Office of Polar Programs, National Science Foundation) as the leader of a field team, which included two divers, Dr. Richard Moe and Mr. Todd Roberts, with considerable diving experience beneath the sea ice of McMurdo Sound.

Our field team had the primary objective of testing the prevailing hypothesis that the Southern Ocean was unproductive during winter due principally to low irradiance. Our work had already taken us to the "land fast" sea ice to study sea ice microbial communities (SIMCO) and water column of McMurdo Sound (approximately 78S latitude) during the late winter to spring transition (Winfly period of August, September, and early October), where we measured significant primary production and bacterial production in the land fast sea ice, but not the water column beneath (Kottmeier et al. 1985). Based upon those results, we were optimistic that these hypotheses could also be tested farther north (64-66S latitude) in the Bellingshausen Sea during late winter.

The nature of our project's scientific research requirements pushed ITT Antarctic Services (ITT/ANS) and Rieber Shipping somewhat to the limit during this first year of operation of the Duke. For instance, we proposed the use of radiotracers to estimate: (1) rates of primary production and synthesis of low molecular weight metabolites, lipids, polysaccharides, and protein by microalgae (fixation of 14C-carbon dioxide), and (2) rates of bacterial production (incorporation of 3H-thymidine). The radiotracer-based research required the features and safety of a radioisotope laboratory van, which had not existed earlier during the first season of operation of the R/V Polar Duke, and a flowing seawater supply on the helicopter deck to provide near in situ temperatures for incubations. An operational dive locker van was also required to support the planned research diving, which was already available on the port side. To safely support radiotracer research and diving, Mr. Skip Owen, ITT/ANS, partitioned the port dive locker van to provide a small radioisotope laboratory van aft of the dive locker space. Smooth, easily cleanable counters, small fume hood, undercounter refrigerator, adequate convenience electrical outlets, and baseboard heaters were provided in the newly created radioisotope laboratory space. While reduced in size, the dive locker space also proved adequate for Dick and Todd to fill tanks and change into/out of their dry suits.

Although spartanly equipped compared to its later years, the only significant pieces of equipment missing aboard the Duke for our research were a liquid scintillation counter (LSC) and an ice machine. Without the feedback from radioassay of experiments counted in an LSC, one had to rely on your experience to ensure that an adequate signal to noise ratio was realized in all experimental incubations. I drew on my experimental experience with SIMCO in McMurdo Sound to design and execute radiotracer experiments with satisfactory results, which were preserved for radioassay in our laboratory at the University of Southern California. I overcame the lack of an ice machine by scraping ice off the deck of the Duke while in the Antarctic study area. Later while employed as the Manager, Laboratory Facilities, McMurdo, by ITT/ANS, I resolved this deficiency by coordinating the installation of the first ice machine to support scientific research (a spare from the Eklund Biological Center) when the Duke visited McMurdo Station during the 1988-89 season.

Maintenance of flowing seawater to and within the plexiglass incubator on the helicopter deck proved to be the challenge that it remains to this day on research vessels working in polar regions. Since our project was the first to attempt such work on the Duke, little was known other than how to pump seawater to that deck. Early freeze up problems were encountered with the seawater line and seawater in the plexiglass incubator enroute to the study area. I decided to simulate the "natural irradiance" and in situ seawater temperatures using fluorescent fixtures and screened bottles, incubated in freezesafes containing seawater and chunks of sea ice. This was conducted beneath the work space counters in the radioisotope van space, creating a very cozy work space.

Extensive sampling of the sea ice was conducted during the cruise. Coring of sea ice cakes 0.20-1.79 meters thick was performed by use of a CRREL auger. Other measurements included measurement of the depth of snow cover and surface/downwelling irradiance. Work on the sea ice was performed by loading sampling gear and personnel into a zodiac staged on the cargo hatch. The zodiac was then craned safely over the starboard rail either into the water or directly onto an ice cake. Return to the Duke was accomplished in reverse fashion.

Research diving proved less problematic on the cruise, due in large measure to the vast experience of Dick and Todd at McMurdo Sound. There seawater close to freezing (-1.9 C) had honed their attention to regulator (double hose) maintenance to avoid freeze up and free-flow, which could prematurely terminate a dive. The well- maintained dive compressor in the dive locker van filled all of the tanks required for the seven dives conducted. A typical dive consisted of the divers donning their underwear and dry suits aboard the Duke. This was followed by loading tanks, masks, fins, and weight belts, plus other research gear, including a tether line into a zodiac. Last, the divers and tender were craned over the starboard rail as per the sea ice work above. Dives averaged less than 5 meters depth and 30 minutes duration, since our focus was on sampling the SIMCO and larval krill associated with the sea ice.

The cruise provided a wealth of information with respect to late winter production in the seawater and sea ice. The first thin bands of sea ice were encountered off Smith Island enroute to the fishing sites off Low Island. Unexpectedly no other significant sea ice was encountered until well south of Palmer Station in the Lemaire Channel, where upturned chunks were discolored by the telltale brown pigmentation of microalgae that had colonized the sea ice. Microbial activity associated with the sea ice examined on the cruise was equivalent to that found in several meters of underlying seawater. Downwelling irradiance was found to be adequate for net production near the surface in ice-free seawater and sea ice. Approximately 40% of newly fixed carbon incorporated by ice microalgae was assimilated into protein, suggesting that net growth was taking place without nutrient limitation. This suggested that annual estimates of primary production should be revised upward significantly to account for this unexpected productivity during late winter in the Southern Ocean.

Coring of the sea ice resulted in further speculation about the late winter food web associated with the sea ice. Samples of larval krill were initially obtained during removal of ice cores, when they appeared in seawater that welled up in core holes. Follow up dives photodocumented an intimate association between swarms of larval krill and the sea ice, which served presumably as a nursery ground. Observation of distinctive green guts in larval krill (collected using an ingenious two-stage tropical fish net designed by Dick) suggested that they were grazing on sea ice microalgae. The sea ice was viewed as a concentrated source of microalgal carbon for the larval krill during late winter when phytoplankton in the water column were scarce. The presence of ctenophores, preying successfully larval krill straying only short distances beneath the sea ice, suggested further that the sea ice served as a refugium for larval krill, analogous to that observed for other polar crustacea (Richardson & Whitaker 1979, Carey 1985, and Kottmeier et al. 1984, 1985). We concluded that the quantity of sea ice associated production and seasonal timing of this production were important factors to consider in Antarctic trophodynamics (Kottmeier and Sullivan 1987).

In large measure the results of our project were possible only because of the "can do" attitude of Captain Mueller and the Rieber Shipping crew, Dr. Langdon Quetin, and the ITT/ANS support staff, which pervaded the Duke in this its first year of operation for the USAP. While I've since participated on numerous other cruises on other icebreakers, it is the spirit of getting the scientific research done while pushing the envelope that I remember most from this first winter cruise aboard the Duke. My heartfelt thanks go to Rieber Shipping for making this cruise a great success.

Literature Cited

Boyd, C.M., Heyraud, M., Boyd, C.N. (1984). Feeding of the Antarctic krill Euphausia superba. J. Crustacean Biol. 4(1): 123-141.

Carey, A. G. (1985). Marine ice fauna: Arctic. In: Horner, R. A. (ed.) Sea ice biota. CRC Press, Boca Raton. Florida. P. 173-190.

Garrison, D. L., Ackley, S. F., Sullivan, C. W. (1986). Sea ice microbial communities in Antarctica. Bioscience 36: 243-250.

Hamner, W. M., Hamner, P. P., Strand, S. W., Gilmer, R. W. (1983). Behavior of Antarctic krill, Euphausia superba: chemoreception, feeding, schooling and molting. Science 220: 433-435.

Holm-Hansen, O., Huntley, M. (1984). Feeding requirements of krill in relation to food sources. J. Crustacean Biol. 4(1): 156-173.

Ikeda, T. Dixon, P. (1982). Body shrinkage as a possible over-wintering mechanism of the Antarctic krill, Euphausia superba Dana. J. exp. mar. Biol. Ecol. 62: 143-151.

Kottmeier, S. T., Muscat, A. M., Craft, L. L., Kastendiek, J. E., Sullivan, C. W. (1984). Ecology of sea-ice microbial communities in McMurdo Sound, Antarctica in 1983. Antarct. J. U.S. 19: 129-131.

Kottmeier, S. T., Miller, M. A., Lizotte, M. P., Craft, L. L., Gulliksen, B., Sullivan, C.W. (1985). Ecology of sea ice microbial communities (SIMCO) during the 1984 winter to summer transition in McMurdo Sound, Antarctica. Antarct. J. U.S. 20: 128-130.

Kottmeier, S. T., Sullivan, C. W. (1987). Late winter primary production and bacterial production in sea ice and seawater west of the Antarctic Peninsula. Mar. Ecol. Prog. Ser. 36: 287-298.

Parfit, M. (1986). A new ship tests the rigor of winter in the Antarctic. Smithsonian 17(8): 116-127.

Richardson, M. G., Whitaker, T. M. (1979). An Antarctic fast-ice food chain: observations on the interaction of the amphipod Pontogeneia antarctica Chevreux with ice-associated micro-algae. Br. Antarct. Surv. Bull. 47: 107-115.