SUBMITTED: Antarctic Journal 1996 REFERENCE AS: Baker, K. S., W. A. Kozlowski, M. Vernet, J. L. Jones, L. B. Quetin, R. M. Ross, R. C. Smith, and W. R. Fraser, Palmer LTER: Annual season October 1995 -March 1996, Antarct. J. U. S. 1996. Palmer LTER Contribution #104 Palmer LTER: Annual Season October 1995-March 1996 Karen S. Baker, Wendy A. Kozlowski, Maria Vernet Marine Research Division Scripps Institution of Oceanography University of California at San Diego La Jolla, CA. 92093 Janice L. Jones, Langdon B. Quetin, Robin M. Ross, Raymond C. Smith Institute for Computational Earth System Science and Marine Science Institute University of California at Santa Barbara Santa Barbara, CA. 93106 William R. Fraser Polar Oceans Research Group Biology Department Montana State University Bozeman, Montana 59717 The Palmer Long-Term Ecological Research (LTER) Pro- gram (Smith et al., 1995) completed a fifth season of sampling at Palmer Station. The Palmer LTER sampling strategy combines seasonal time series data from the nearshore Palmer grid and seabird observations from nest- ing sites near Palmer Station with annual cruises which cover a regional grid along the western Antarctic Penin- sula. The LTER January cruise (PD96-01) visited the inshore stations five times to provide continuity in the seasonal record (Vernet and Baker, this issue). A summary of events for the 1995/96 Palmer field season is given in Table 1. Significant dates include arrival of research teams at Palmer (7 October 1995), first bird observations (10 October 1995), first chloro- phyll sample (16 November 1995), first zodiac profiling cast and acoustic transect (16 November 1995), cruise begin (8 January 1995), cruise end (10 February 1996), last profiling cast and acoustic transect (19 March 1995), departure of water-column research teams from Pal- mer (26 March 1996), and last bird observation (27 March 1996). In Table 1 each line summarizes one cycle of standard sampling (see Table 1, Baker et al, this issue) consisting of approximately 7 days where the initial event number, month begin, day begin, day, and year are given in the first five columns. The sixth column summar- izes the types of standard days included in this particu- lar cycle. A summary of the thirteen SCUBA dives to obtain krill samples for laboratory experiments, acoustic transects, hydrographic and optical profiling, phyto- plankton sampling, targeted krill tows for physiological condition and instantaneous growth rate experiments, and zooplankton trawls are given in the next columns followed by general comments. There were some changes from past seasons in the sampling program. One change was an equipment upgrade so that instruments, winch, and computers on the zodiacs now run on batteries rather than a gasoline generator. Bat- teries have proven a more reliable, stable, cleaner and quieter power source than the generator. Chlorophyll samples, routinely run using HA 0.45 Mm filters, were also run separately for the <20 Mm fraction of phyto- plankton at selected depths After visits were made to the Hugo Automatic Weather Station during the LTER annual January cruise, a return attempt was made on 23 March to correct a temperature probe failure but high swells prevented landing. The season was preceded by a heavy ice winter as was also true of the first Palmer LTER season 9192 when Arthur Harbor did not clear of pack ice until early December (Ross and Quetin, 1992). During 9596 season, the timing of the ice departure differed. Sea ice began to clear from the nearshore Palmer grid in November 1995, but a return of sea ice on 17 December preventing sam- pling for over a week until high winds blew the harbor clear of ice on 24-25 December. Figure 1 shows the seasonal progression in selected parameters versus time. These preliminary data provide an overview of the season. The 9596 season was a period of high biomass with an initial phytoplankton bloom of 15 mg/m3 in November 1995, chlorophylls greater than 10 mg/m3 after January, and another bloom reaching 35 mg/m3 in February 1996. The silicate and nitrate decreased concurrently, reaching low values of 36.5 MM silicate and 2.24 MM nitrate when chlorophyll peaked at 38.9 mg/m3. Between November 20 and March 19, 21 acoustic transects were run from stations A to E, and 15 from F to J. Net samples indicate that young-of-the-year krill dom- inated the zooplankton; salps were absent. Acoustic estimates of zooplankton biomass ranged from 0 to 382 g/m2, with most of the higher values found from the third week in February to the middle of March. Some of the reproductive events associated with breeding chronology of Ade'lie penguins on Humble Island this season (Fraser et al., in press) are noted by arrows in Figure 1c. The breeding success of these penguins was 1.58 chicks creched per pair, representing a small increase relative to last year. The LTER seasonal observations of the marine environment, the lower-trophic level abundance and dis- tributions for the area, and the seabird observations at nesting sites near Palmer were recorded from October 1995 to March 1996. The sampling event log, participant list and other project information for the season are avail- able online (http://www.icess.ucsb.edu/lter). Acknowledgement and thanks are given to members of the Palmer LTER research team and of Antarctic Support Associates. This research was supported by National Sci- ence Foundation grant OPP90-11927 and is Palmer LTER Con- tribution No. xx. References Baker, K.S., M.Vernet, W.A.Kozlowski, R.C.Smith, J.L.Jones, R.M.Ross, L.B.Quetin, and W.R.Fraser, 1996. Palmer LTER: Annual Season Sampling on Station. Antarctic Journal, this issue. Fraser, W., D. Patterson, E. Holm, K. Carney and J. Carl- son (in press) Seabird research undertaken as part of the NMFS/AMLR ecosystem monitoring program at Palmer Station, 1995/96 in AMLR 1995/96 Field Season Report: Objectives, Accomplishments and Tentative Conclusions. J.Martin (ed). Southwest Fisheries Science Center. Ross, R.M. and L.B. Quetin, 1992. Palmer Long-Term Eco- logical Research (LTER): an overview of the 1991-1992 season. Antarctic Journal 27(5):235-236. Smith, R.C., et al. 1995. The Palmer LTER: A long-term ecological research program at Palmer Station, Antarctica. Oceanography. 8, 77-96. Vernet, M. and K.S. Baker, 1996. Palmer LTER: Annual January Cruise for 1996 (PD96-01). Antarctic Journal, this issue. Figure Legends Figure 1a: Air temperature [degC] (solid line) at Palmer station and water temperature [degC] (boxes) at Station E for the 9596 season. Figure 1b: Surface chlorophyll [mg/m3] (filled diamonds), nitrate [MM] (open squares), and silicate [MM] (filled squares) at Station E for the 9596 season. Figure 1c: Krill abundance [g/m2] (filled squares) from transect A to E and Ade'lie penguin foraging [hrs] (open squares). Arrows indicating day of first egg laying, first brood, first creche, first fledging, and peak fledging at Humble Island for the 9596 season. Table Legend Table 1: Palmer LTER 1995/1996 Event Log Overview of 1995/1996 season by sampling week (see Baker et al, this issue, Table 1, for definition of standard sampling week). Events include acoustics (bio-ac, Biosonics 120KHz), discrete sample for chlorophyll analysis (chl), conductivity-temperature-depth (ctd, Seabird), SCUBA krill collection (dive), high performance liquid chromo- tography of phytoplankton pigments (hplc), instantaneous growth rate (igr), targeted tow for krill (krilltarg, 50KHz), microscopic analysis of net plankton (net, >5Mm), inorganic nutrient analysis (nuts), photosynthetically active radiation (par), physiological condition of larvae (phyconl), microscopic analysis of picoplankton (pico, 0.5-5.0Mm), particulate organic carbon (poc), production photosynthesis vs irradiance (Ppi), primary production simulated-in-situ (Psis), profiling radiometer (prr, BSI), discrete sample for salinity analysis (sal), tran- sparent exopolymer particles (tep). and standard zoo- plankton tows (trwl).