Sixth Weekly Report -- NBP01-05 Palmer LTER Sea Ice Cruise 15-21 October, 2001 Throughout most of this week we continued to be beset in very heavy snow and ice. Conditions were such that science activity was relatively restricted. We had limited access to the ice and did so by making use of the personnel basket from the bow of the ship. In spite of these limitations, we had several opportunities, when weather conditions and safety considerations permited, to carry out observations and collect samples from the ice. We continue to operate with the CTD off the stern of the ship (where we can sometimes maintain open water) but this option is viable only when air temperatures are above about -5C (which it was not for much of the week). Late on the 19th, a storm with gale force winds from the SE created even more ridging in the vicinity of the ship but also began to loosen the pack in general. Early AM on the 20th Captain Joe Borkowski, Ice Pilot Vladimir Repin, and mates David, Fahey, Richard Wisner and John Higdon skillfully extracted the NBP from the heavily ridged area, found leads in the vicinity and we began to make our way out of the heavy ice. By early AM on the 21st we crossed the ice edge and into open water. We are now making our way toward Palmer Station periodically dropping XCDTs in route. All science groups are greatly appreciative of the outstanding support from MPC Randy Sliester, MST Mo Hodgins, MTs Matt Burke and Stian Alsendrini, ETs Jeff Otten and Roman Botko, and ITs Kevin Bliss and Julianne Lamsek. The professional dedication and excellent support to our science activities by Capt. Joe and all his crew and the Raytheon team provided us with the opportunity to carry on our science under the most difficult ice conditions.. The Palmer LTER and VIMS scientists are most thankful for their outstanding help throughout the cruise. Individual group reports follow. BP-013 (Chris Denker, Heidi Geisz-for Bill Fraser) BP-016 (M. Vernet, W. Kozlowski, K. Sines, K. Pelletreau, I. Garibotti, and P. Yeh. Andrew Ross from Oregon State University provides nutrient analysis.) During the week of 15-21 October, the phytoplankton group within the LTER 2001 Ice cruise continued field sampling and experiments to characterize the ice and plankton communities at the mouth of Marguerite Bay. Water column was sampled with a CTD rosette or with Niskin bottles deployed from the ice. No ice melting was observed in the water column, with salinity and particle concentrations remaining at winter values. Phytoplankton biomass and primary production in the water column remain low (i.e. 0.04 milligrams chlorophyll a per cubic). Plankton communities are low-light adapted (Pmax = 0.41 mg C mg chla-1 h-1). Macronutrient concentrations are high at the mixed layer: phosphate 2.1 micromolar, nitrate 30 micromolar, silicic acid 70 micromolar. Chlorophyll concentrations at the snow-ice interface continue to grow. Size fractionation studies show a wide range of particle size within the ice communities and differential sensitivity to light as a function of cell size. For example, particles < 1 micrometer can have chlorophyll a concentrations of 2.9 mg m-3 and P max = 0.11 mg C mg chla-1 h-1. The fraction < 5 um and with 6 mg chla m-3 has a Pmax of 0.25 mg C mg chla-1 h-1 and the total fraction a concentration of 37 mg chla m-3 and P max of 0.8 mg C mg chla-1 h-1. In addition to field sampling, we have carried experiments on the effect of ultraviolet radiation on carbon uptake on ice communities and growth experiments on ice and plankton populations. Analysis of ice cores is done in collaboration with Smith's group and biological analysis of cores is done jointly with Karl's, Ducklow's and Quetin's groups. BP-021 (Rich Iannuzzi & Raul Guerrero, for Doug Martinson) The physical oceanography team made 5 CTD casts from 00:00 Oct. 14 to 23:00 Oct. 21 bringing the cruise total to 59. All the casts of this week were performed from the A- frame with the rosette remaining on the back deck for the whole week. CTD operations are now complete for the cruise as we are out of the ice and headed for port. The rosette will be moved from the back deck to the helicopter hanger for safe storage during the return trip. Continued maintenance of the 2 conductivity cells showed stable offset. 3 XCTD's were dropped on the grid in transit to Palmer station and XCTD drops will continue until we run out. XBT drops will then take place as we return from Palmer Station to Punta Arenas as occurred on the way south. Due to the relatively stable position of the ship over the past week, the temperature and salinity data collected from the CTD is also being considered as a time series and color contour time plots have been created and examined for this purpose. Finally, throughout the cruise Rich Iannuzzi has maintained a daily email contact with a 4th grade class as part of the LTER education outreach. Karen Baker has supported the operation from the home side, including the posting of Rich's daily email message and digital photographs to http://pal.lternet.edu/field/0102season/01sep/outreach. BP-028 (Langdon Quetin, Charlie Boch, Amy Kaiser, Tim Newberger, Stephanie Oakes, Holly Rodrigues, Jordan Watson, Jenny White) >From October 15-21 no diving occurred and no additional krill larvae were collected. We completed larval ingestion, fecal pellet production and growth experiments on board with larval stocks maintained in the aquarium room on board. The data for the growth experiments has been entered and results indicate that larval growth per inter- molt period is low this time of year. Growth rates based on length frequency analysis indicates the larvae have continued to grow slowly during the cruise period. On Oct 20 the ship broke free from the ice. We are now busy cleaning equipment and packing in preparation for leaving some equipment at Palmer Station. We will load larger equipment onto the Laurence M. Gould at Punta Arenas for it more assured and safer return to Palmer Station. Our group wishes to thank everyone aboard for making our "ice time" most enjoyable. Not enough can be said about the excellence of the support from the Raytheon employees on board and Captain Joe and crew of the Nathaniel B. Palmer. BP-032 (Ray Smith, Enrique Curchister, Rob Massom, Yuko Massom & Sharon Stammerjohn) The snow and ice conditions continued to reflect the high degree of divergence and deformation in Marguerite Bay due to the persistence of winds with a northerly component. The our snow/ice & optics group carried out science activities on the ice for three days during this week, extracting cores and snow samples for detailed analysis and making optical measurement on snow and ice. Being beset has allowed us to monitor the evolution of the ice and its snow cover in detail. Microphotographs of the different snow types present revealed that the snow was largely coarse-grained and icy in character, due to periodic high temperatures. Almost daily snowfall was again characteristic of the area. Observations during this week have confirmed that the snow ice layer between the snow and sea ice proper is a widespread substrate for rich phytoplankton growth. Ice cores were collected and analyzed in support of the biology and optical experiments. Thick and thin sections on ice cores reveal complex evolution of the ice in this area. Optics experiments were carried out for both snow and ice. Chlorophyll, nutrient and oxygen isotope analyses continued for all snow, ice and water samples. Once under way, hourly observations of snow and ice thickness have also been collected according to standard protocol. These observations continue to show increasing presence of ice algae. The ice team is especially appreciative of Capt Joe, his crew and the Raytheon team for working with us to maintain access to the ice under these unusual and difficult conditions. BP - 045: (Rebecca Dickhut, Hugh Ducklow, Amy Chiuchiolo and Shelby Walker) "Persistent Organic Pollutants in Antarctic Sea Ice" The VIMS group completed winter/spring sample collections for POPs during week six by collecting one additional high volume ice sample, two additional high volume water samples to complete a five point depth profile just outside of Marguerite Bay, and two additional high volume air samples. In sum, 35 air, 16 water, 5 snow (one additional snow sample will be collected near Palmer Station) and 6 sea ice samples were collected during the winter ice cruise. When analyzed, these data will greatly enhance our understanding of the seasonal distribution, transport and fate of POPs in the coastal Antarctic ecosystem. BP-046 (Chris Carrillo, Matt Church, Shaun Johnston & Tamara Pease for Dave Karl) BP-046 would also like to thank the Captain and crew of the NBP for extracting us out of the ice and sending us on our way home. Although many of the original scientific objectives were not met because of severe ice conditions, the rare observations and measurements made on this cruise should further our understanding of ice processes during the austral winter period. BP-046 signs off until next time. Respectively submitted, Ray Smith, Chief Scientist