AntJ/19Nov98 Palmer LTER: Annual January Cruise for 1998 (LMGR98-8; LMG98-1) David M. Karl, Langdon B. Quetin, and Karen S. Baker Marine Research Division Scripps Institution of Oceanography University of California at San Diego San Diego, CA, 92122 Annual sampling for the sixth Palmer Long-Term Ecological Research (LTER) January cruise was completed in two legs and adds to our growing observation of the area West of the Antarctic Peninsula (Ross et al, 1996). Zooplankton sampling and bird observations within the foraging range of penguins near Palmer Station (high density grid) was performed aboard the Research Vessel Abel-J (LMGR98-8: 18Jan-24Jan) with 5 crew and 9 LTER science participants. The full LTER grid (transect lines 600-200) and additional inshore station sampling were performed aboard the Antarctic Supply and Research Vessel Laurence M. Gould (LMG98-1: 28Jan-13Feb) with 15 crew, 5 Antarctic Support Associates, and 21 LTER participants. The November 19, 1998 - 2 - cruise began one week later than the preceding annual LTER cruises (Ross and Baker, 1997) with the charter of the Abel-J for the first leg of the cruise because of the end of RV Polar Duke contract and the delay in the maiden voyage of the newly built ASRV L.M.Gould. Tables 1 and 2 summarize the chronology and sampling division of the cruise, respectively. These tables summarize both the sampling over the mesoscale grid (Figure 1) and the higher density observations within the foraging range of Adelie penguins near Palmer Station (Figure 2). Initial nearshore Palmer work on the first cruise leg included repeat visits to nearshore stations (E, B, H, I, J), two transects (picket lines), which maintained a fixed dis- tance from Palmer Stations (PL 3.7 and 10 km), and the high density grid (HD1 10 km x 20 km) with five hydrographic sta- tions. Stations on the LTER mesoscale grid were occupied including (600.040, 060, and 080) followed on 23 January by four inshore stations in the Lemaire and Grandidier. Station measurements included optics using a profiling radiometer and hydrography using the station CTD deployed to a depth of 100m. Six 5 liter Go-Flo bottles deployed routinely from the port side using a hand winch collected water for nutrients, plant pigments, primary production, and plant physiology. A Palmer zodiac was used to collect krill. Bioacoustic surveys were completed aboard the Abel-J at 4.5 knots, the ship's minimum November 19, 1998 - 3 - speed. Water for nutrient and productivity measurements was taken back to Palmer station. Nutrients were shipped to the University of California at Santa Barbara Analytic Facility for analysis. On 22 January batteries were replaced at the the Hugo Automatic Weather Station (AWS). The AWS electronics box was removed in order to replace components and returned on 24 January restoring the station to full functionality. Time at Hugo permitted a complete bird survey of the Hugo archipelago. During the second cruise leg, stations on grid line tran- sects 600 through 200 were completed with 20 km station spac- ing on grid lines 600, 500 and 200 and 40 km station spacing on grid lines 300 and 400 using XBT's to fill at 20 km spac- ing. In order to simplify equipment and personnel support, the light and hydrographic measurements were performed on separate casts unlike the past five annual cruises. Profile measure- ments included hydrographic casts using the ship's CTD to 500m with twelve liter Go-Flo bottles run from a starboard Baltic Room as well as separate radiometer casts. Other measurements included microbial parameters, plant pigments, nutrients, pri- mary production, plant physiology, and krill physiological measurements. Bio-acoustic transects and net tows were per- formed at 20 km spacing on all transect lines. Some planned acoustic work was canceled due to bubble sweep from the hull on the 3.5 kHz transducer port. Continuous underway November 19, 1998 - 4 - measurement systems logged partial pressure of carbon dioxide, pH, dissolved oxygen, fluorescence, temperature and conduc- tivity of near surface waters. Adelie penguin diet samples were collected at Ginger Island toward the end of the cruise before proceeding to inshore stations in the South (Tickle Passage, Crystal Sound) and the North (Grandidier, Lemaire). The cruise ended with repeat visits to station 600.040 and nearshore stations B and E. On January 30, the LTER sediment trap mooring near Hugo was recovered and redeployed while an attempted trap deploy- ment at Marguerite Bay February 10 was aborted. As part of the Palmer LTER Education Outreach, Ms. Besse Dawson, a high school marine sciences teacher from Texas, was aboard ship as an NSF Teachers Experiencing Antarctica (TEA) participant. She communicated to online classrooms through real time field reports via the world wide web. Palmer LTER personnel also helped with the XBT Drake Passage Program (Ray Peterson, Dan Roemmich and Janet Sprintall) of Scripps Insti- tution of Oceanography during the northbound Drake crossing. Ice-free open water was observed during most of the cruise. Brash ice was encountered in the Lemaire (inshore North) and Tickle Passage (inshore South). High winds were encountered on 18 January during coastal sampling, on 31 Janu- ary preventing 600.200 offshore sampling and on 07 February November 19, 1998 - 5 - during sampling of the mid 200 transect line. For the 97-98 season, one foraging grid rather than two was completed. Ship-based censuses in the Adelie penguin foraging area from both the Abel-J and the Gould suggest that birds were concentrated inshore within 15 km of their rook- eries. This pattern is in agreement with other data, includ- ing shorter foraging trip durations relative to the 96-97 sea- son and the presence of large numbers of small krill in their diets. An item that will be the subject of further discus- sions is the fact that compared to our former research vessel (Polar Duke), the Lawrence M. Gould affords much inferior visibility from its bridge for seabird and marine mammal cen- suses. Chlorophyll concentrations indicate low phytoplankton standing stocks throughout the study region averaging less than 1-2mg Chl/m3 even in the nearshore stations. The fre- quently observed onshore-to-offshore gradients in chlorophyll [Smith et al, 1998] are minimal this year as they were last year. Further, the South to North chlorophyll gradient is entirely absent. Surface dissolved oxygen and dissolved carbon dioxide concentrations indicate that both biogenic gases are essentially at equilibrium with the atmosphere unlike previous years with supersaturated dissolved oxygen and undersaturated carbon dioxide. Indications are that primary production is low compared to previous years. Large interannual variations in November 19, 1998 - 6 - magnitude and timing of the spring-summer export have been documented. The 96-97 sediment trap samples gave dramatic visual evidence for a large export flux event for a period of about two weeks during late December 1996-early January 1997, but no comparable export event was observed in the 97-98 sam- ples through this past austral summer prior to 8 January 1998. How the ecosystem changes observed relate to the 1997-98 El Nino events will be the subject of further investigation. This research cruise was composed of the Palmer LTER research team including team leaders P.Duley (Fraser,S-013), C.Johnson (Smith,S-032), D.Karl (Karl,S-046), W.Kozlowski (Vernet,S-016) L.Quetin (Quetin/Ross,S-028). Special thanks to the Palmer LTER research team members, the Antarctic Sup- port Associates as well as the Captain and crew of the Abel-J and the L.M.Gould. This material is based upon work supported by the National Science Foundation under Award No. OPP-9632763 with additional funding provided by the Regents at the Univer- sity of California. Palmer LTER Contribution No. xx. References Ross, R.M. and K.S. Baker. 1997. LTER: Annual January Cruise for 1997 (PD97-1). Antarctic Journal of the United States (accepted). Ross, R.M., E.E. Hofmann, and L.B. Quetin (eds). 1996. Foun- dations for Ecological Research West of the Antarctic November 19, 1998 - 7 - Peninsula. AGU Antarctic Research Series, volume 70, 448 pages. Smith, R.C., K.S. Baker, and M. Vernet. 1998. Seasonal and interannual variability of phytoplankton biomass west of the Antarctic Peninsula, Journal of Marine Systems (in press). Figure Captions Figure 1. The cardinal stations of the Palmer LTER regional grid (dots) off the Antarctic Peninsula are overlaid for LMG98-1 with large dots to indicate stations occupied, with x's to indicate XBT stations and diamonds to represent inshore stations. Sediment trap stations are marked with triangles. Labeled are Anvers Island (1) with Palmer Station (o), Hugo AWS (H), Adelaide Island (2), Lemaire Channel(L), Grandidier (G), Crystal Sound (C), Tickle Passage (T), Marguerite Bay (B), Rothera Station (R), and Ginger Island (open square). The 1,000-meter bathymetry line (dotted) is shown. Figure 2. Sampling area near Palmer Station on Anvers Island with the Neumeyer (N) and Gerlache Strait to the east. The Hugo automatic weather station (H) location is given. The high density sample grid (HD1) is shown with CTD stations (triangles). Palmer stations B, E and J are shown (open cir- cles). The LTER regional grid 600 line stations 040, 060 and 080 (filled dots) and inshore stations (diamonds) are shown. November 19, 1998 - 8 - November 19, 1998