Third Weekly Report NBP01-05 Palmer LTER Sea Ice Cruise 24 - 30 September, 2001 September 2001 seems to be the month of distressing news. With the terrible events in DC and NY, Doug Martinson's operation, and now we have received the disastrous news that the Bonner Lab at Rothera Station was consumed by a fire. It is unsettling to realize that just a week ago Deputy Base Commander Mr. Pete Milner and others extended their hospitality to us during a short courtesy call at the station. Our sincerest condolences go out to our BAS friends and colleagues for this disaster. We are thankful that no one was injured. We began the week with the goal of transiting from the polynya area south east of Adeliade Island to the location of ice buoy #7949 (that continues to send back position and data), a distance of roughly 70 nautical miles. Instead, we have encountered wind, snow and pack ice conditions that have held the NBP to speeds such that we have been able to make only a few nautical miles per day. These conditions are outside the experience of all on board. Winds were persistent from the north during most of the week, pushing the pack to the south, putting the ice under considerable pressure and leading to heavy rafting and ridging of the pack. Indeed, we have seen flows break with part being subducted as the other part overrafts with the formation of ridges. Plate tetonics writ small in real time. Snow depths, on level floes, are 30-60cm. Ice thickness typically 0.7 to 1.2 meters with consolidated ridges covering 20-50% of the area. Measurement of snow conditions, ice thickness and freeboard along transects reveal a predominance of negative freeboards and the common presence of slush layers. In some areas the snow is so thick that the freeboard is as much as a negative 35 cm, giving rise to a relatively thick slush/water layer. Algae is associated with these layers. Diver observations suggest the presence of significantly more over rafting than is estimated by above surface observations. These combined influences make "ice breaking" under these conditions akin to pounding sand. While frustrating, we are dealing with and learning much about snow and ice conditions not previously experienced. It seems clear that these conditions will play a significant role in the ecology of the area. During the week we occupied two short ice stations (24th and 30th) and on the 25th we established a second ice process station. This station was occupied for 2.5 days before it was interrupted by blizzard conditions. During the past few days of continual backing and ramming we have averaged less than a few miles per day. Captain Joe Borkowski, ice pilot Vladimir Repin and mates David Fahey, Richard Wisner and John Higdon have done an outstanding job in handling the ship and in providing support to our science activities under these difficult conditions. MPC Randy Sliester and his RPSC staff are also providing outstanding support. The science groups are working as an integrated team and moral is high. As the week ended, we are beset in the ice conditions described above. Individual group reports follow. BP-013 (Chris Denker, Heidi Geisz, for Bill Fraser) Bird observations were continued throughout the week. Although we are relatively close to land, we saw few penguins on the ice and suspect this is due to the tight pack condition of the ice. Adelie penguins were sighted sporadically in small groups of 3 to 4 in the early morning hours. Other sightings include snow petrels, giant petrels, kelp gulls (including an immature bird), an Antarctic petrel and crabeater seals. We continued following the satellite tagged Adelies. Most of the birds are still located in the Marguerite Bay polynya, while two birds have headed north, one of which has passed Anvers Island. BP-016 (M. Vernet, W. Kozlowski, K. Sines, K. Pelletreau, I. Garibotti, and P. Yeh. Nutrient analyses are provided by Andrew Ross from Oregon State University) During the week of 24-30 September, the phytoplankton group within the LTER 2001 Ice cruise sampled in waters adjacent to the mouth of Marguerite Bay. Phytoplankton biomass and primary production in the water column remain low (i.e. < 0.5 milligrams chlorophyll a per cubic meter). Surface nutrient concentrations are high and constant throughout the mixed layer. Variable fluorescence measured by a Fast Repetition Rate Fluorometer (FRRF) continues to be low throughout the mixed layer. Ice communities in this area contrast with the low phytoplankton activity. Photosynthesis in ice communities, measured as Photosynthesis versus Irradiance curves, shows light adaptation within the ice. Surface samples (top 0-20 cm) saturate photosynthesis rates at higher irradiance, compared to bottom communities (deeper than 40 cm). Maximum photosynthetic rates are also high (Pmax = 5.8 mgC mgchla-1 h-1, light-limited photosynthesis = 0.01 mgC mg chla-1 h-1 per microE m-2 s-1 & light saturation (Ik) at 259 microE m-2 s-1). BP-021 (Rich Iannuzzi & Raul Guerrero, for Doug Martinson) The physical oceanography team made 10 CTD casts from 00:00 Sept. 24 to 23:00 Sept. 30 bringing the cruise total to 39. At the start of the week the CTD was being cast from the Baltic room, but at the second ice station, the rosette was again moved to the A-Frame and cast off the stern. On the night of Sept. 27, the first day of ice process station #2, the CTD was yoyo'ed 4 times to the bottom (roughly 390 m.). The profile change was on the order of sensor noise, but drift was minimal and weather conditions relatively calm. We will likely adopt a strategy of casts every 4-6 hours if we are fortunate enough to have another multi-day ice station. On the second day of the ice station, 2 casts were made, but a third was cancelled in the evening because ice was creeping across the stern from the port side. Another cast was not completed at this station as the weather turned and it was decided to leave the rosette on the back deck, strapped down and wrapped for warmth as we began transit. This worked fine. After losing 2 days due to weather and ice conditions we resumed CTD operations on Sept. 30 and made 3 successful casts at a mini ice station, but had some problems with ice formation on the instruments while on deck, notably secondary salinity and secondary pump. These problems have been resolved for now. Continued maintenance of the 2 conductivity cells show stable offset. CFC on three casts were collected for Bill Smethie of Lamont Doherty Earth Observatory. BP-028 (Langdon Quetin, Charlie Boch, Amy Kaiser, Tim Newberger, Stephanie Oakes, Holly Rodrigues, Jordan Watson, Jenny White) From September 24 to September 30 we spent 5 days in transit and/or dealing with unfavorable ice conditions. We have collected ice and brine at two shortened ice stations for feeding experiments with krill larvae and collected larvae during two dives at one 2-day ice station before high winds made it impossible to continue. Despite the limited sampling time feeding experiments of krill larvae on natural assemblages of micro fauna continue uninterrupted with 7 experiments completed to date. In addition, after much work to open two dive holes in one meter of ice at ice process station #2, we were able to collect krill to renew our stocks on board, start 2 more experiments on krill growth and preserve samples for later analysis. We were also able to assess the feeding rate and fecal pellet production of freshly caught larvae. Dominant larval stages are Furcilia 6 and Juvenile. During the dives we noted krill larvae continue to feed predominantly on ice floors, but also in pockets in the sides of floes with little feeding on ice ceilings. Results on how actively the larvae are feeding will have to wait for further analysis, but preliminary results from the growth experiments suggest that the inter-molt period will be greater than 30 days, typical of mid-winter inter-molt periods. BP-032 (Ray Smith, Enrique Curchister, Rob Massom, Yuko Massom & Sharon Stammerjohn) During the past week three ice stations have been conducted two short (2-4 hours) and one long (two days). At these stations the snow, ice & optics team completed: two (50m and 30m) snow, wicked, slush & ice thickness transect including snow/ice temperatures and ice freeboard; detailed snow data from 5 snowpits including structural analysis, temp, salinity and d18O analysis; nine core sites for core physics including temp, salinity, d18O, chl and ice structure analysis in concert with cores for biological and chemical analysis; multiple cores for biological and POP analysis; and one abbreviated bamboo thickness array was set out but blizzard conditions prevented it from being recovered. Optical data sets for spectral albedo, snow & ice transmittance were obtained at each ice station and snow pits & ice cores were taken at the optics sites to characterize the conditions. Chlorophyll analysis for water column (from CTD casts) as well as snow & ice samples continues. A consistent feature of our environment has been the isothermal nature of the snow and ice strata, due to persisting warm and northerly winds. This weather pattern has deposited a significant amount of snowfall, which has been redistributed by accompanying strong winds into thick low dunes and sastrugi (the latter in the lee of ice surface roughness features, and up to 1.5 m thick). This has led to an unusually high estimated average snow thickness of ~40 cm. Sea ice conditions continue to be dominated by rafted and heavily ridged first-year ice, with an average thickness of ~90 cm, which the persistent northerly winds have compacted. The combined effect of thick snow and heavily deformed ice has made ship progress slow. Due to the loading effect of the snow overburden and high air temperatures, the sea ice-snow interface is typically flooded, leading to widespread snow-ice formation and a high basal salinity. This stratum appears to form a rich refuge for rapid phytoplankton growth. Samples have been collected for detailed nutrient, oxygen isotope and chlorophyll analysis. BP - 045: (Rebecca Dickhut, Hugh Ducklow, Amy Chiuchiolo and Shelby Walker) The VIMS group continued sampling for Persistent Organic Pollutants (POPs) and bacterial processes during the past week. Snow samples for POPs were collected at LTER grid station 200.-020 and ice process station #2, respectively. Replicate ice samples, surface water and pycnocline water samples were also collected at ice station 2. By measuring POPs in seasonal snow and ice, we can evaluate the magnitude of POP release that will occur during spring/summer as the snow/ice melts. During week 3, air samples for POPs were not collected due to the necessity to maintain and recalibrate the instruments, as well as poor relative wind direction at ice station 2. Air sampling was reinitiated after departure from ice station 2 with improved relative wind direction. Bacterial ecology: We sampled full-depth CTD profiles at LTER grid stations 200.-080 and 200.-020 for bacterial abundance, thymidine and leucine incorporation rates. We obtained a full set of ice cores at Ice Station 2 for biological and bacteriological analyses. This collection included both integrated (unsectioned) cores and others sectioned for vertical profiles. Both untreated cores, and cores diluted with filtered seawater were assayed for bacterial production rates. Dilution is performed to minimize cell lysis as the low salinity ice is melted. By comparing bacterial rates in diluted vs undiluted samples, we can investigate the effects of dissolved organic matter release from lysed cells. All depth strata sampled in the cores contained abundant bacteria (relative to the water column), including large cells, filaments and other morphotypes, as well as diverse microalgae and protozoans. Intact core sections were also saved for chemical analysis of dissolved organic matter composition. Our group acknowledges in particular the assistance of Rob Massom, Ray Smith and Sharon Stammerjohn, and of Maria Vernet and her team in obtaining ice cores for POP and bacteriological analyses, respectively. BP-046 (Chris Carrillo, Matt Church, Shaun Johnston, Tamara Pease for Dave Karl) Oxygen concentrations remain low (undersaturated with respect to the atmosphere) at all stations. Concentrations range from 315 to 320 uM/l. Significant differences are not observed between samples taken from CTD casts and samples obtained from Niskin bottles lowered through holes drilled into the ice. The partial pressure of carbon dioxide (pCO2) remains supersaturated with respect to the atmosphere throughout the cruise track with values ranging from 390 to 420 uatm. Significant differences are observed in ectoenzyme activity (Leucine aminopeptidase) between water column samples and samples obtained within ice cores. Ice values range from 8.36 to 29.34 nM/hr while surface waters range from 0.04 to 2.33 nM/hr. A second set of particle interceptor traps were deployed and retrieved at Ice Station 2. A significant amount of swimmers (krill) were caught within the traps. Respectively Submitted, Ray Smith Chief Scientist