SUBMITTED: AntJ/10Nov97 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 1996 -March 1997, Antarct. J. U. S. 1997. Palmer LTER: Annual Season October 1996-March 1997 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 sixth 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 (PD97-01) visited the Pal- mer Basin inshore stations four times to provide con- tinuity in the seasonal record (Ross and Baker, this issue). A summary of events for the 1996/97 Palmer field season is given in Tables 1 where Table 1a gives the weekly standard sampling plan which varied somewhat and Table 1b gives the season's sampling overview. An addi- tional activity late in the season was excavation of penguin rookery sediments for local paleo studies (S.Emslie). Significant dates include arrival of research teams at Palmer (11 November 1996), first bird observations (13 October 1996), first chlorophyll sample (20 November 1996), first zodiac profiling cast (20 November 1996), first acoustic transect (22 November 1996), start of cruise (11 January 1997), end of cruise (13 February 1997), arrival of paleo team (03 March 1997), last profiling cast (18 March 1997), acoustic transect (21 March 1997), last LTER bird observation (16 April 1997), departure of water-column research teams from Palmer Station (04 April 1997), and bird and paleo departure from Palmer Station (17 April 1997). In Table 1b each line summarizes one cycle of standard sampling (from Table 1a) Initial event number, month begin, day begin, day end, and year are given in the first five columns. The sixth column summarizes the types of stan- dard days included in this particular cycle which a prime indicates a subset of that standard day. Acoustic tran- sects, hydrographic and optical profiling, phytoplankton sampling, targeted krill tows for physiological condition and instantaneous growth rate experiments are given in the next columns followed by general comments. There were some changes from past seasons in the sampling program. With six LTER personnel for the 1996- 1997 season (1/S016; 1/S032; 1/S028; 1/share; 2/S035) rather than ten as in 1995-1996 (3/S016; 1.5/S032; 2.5/S028; 3/S035 ), the daily sampling week was reduced to sampling 5 stations instead of 9 for weekly profiling hydro-bio-optics, 2 stations twice weekly instead of 4 for phytoplankton sampling, growth experiments every 2 weeks instead of weekly, dropping krill collection by dives, standard tows, and phosphate measurements. Further, only the sum of nitrite and nitrate were meas- ured rather than the individual components while nutrients taken on station at the start of the season were run concurrently with cruise samples when additional personnel were available. The hardware and software for HPLC and nutrient analysis remained the same as last year. Equipment upgrades included addition of an anemome- ter for wind speed and a thermometer for air temperature on the ROZE. Also, this season the satellite network link LES9 provided two blocks of approximately 5 hours of online time per day making possible FTP file transfer of data and real-time electronic talk communication. The data transfer served as both a method of data archive as well as the conduit enabling real-time data analysis at home institutions. In addition to standard chlorophyll samples run in replicate for the greater than 0.45 Mm phytoplankton at selected depths, the <20 Mm fraction was sampled at the 50% light level (ranging from 2.5m to 19m). Hydrographic profiles were also run as requested at station Janus (D.Karentz, S007, personal communication) and at the pier (T.Amos, personal communication). Concurrent deployment with the stations STD instrument will permit intercom- parison studies. During the 9697 USAP season, there was no consoli- dated ice in September 1996. High winds throughout the month of October contributed to ice movement, and the last of the pack ice left on 29 October. Brash ice con- tinued to appear sporadically through April, accompanied by high winds. This pattern differed from that of 9596 when the spring/summer was preceded by a heavy ice winter, and pack ice did not begin to clear from the nearshore Palmer region until November 1995. Preliminary data show seasonal progression in selected parameters through the spring and summer (Figure 1), providing an overview of the season. The 9697 season showed average to low chlorophyll biomass with initial surface phytoplankton blooms of 5-10 mg/m3 in November at station B and in December at station E. Chlorophyll con- centrations remained below 1-3 mg/m3 through January, followed by another short bloom reaching 5 mg/m3 occurred in February 1997 at station E. The nitrate-nitrite showed less pronounced bloom activity this season compared with last season. Between November 22 and March 21, 14 acoustic tran- sects were run from stations A to E (Figure 1c), and 14 from F to J. Acoustic biomass in the spring and early summer was generally less than 100 gm/m2, whereas from mid-January to mid-February acoustic biomass was between 100 and 500 g/m2, decreasing to extremely low values in late February and early March. Length frequency distri- butions of Antarctic krill collected with target tows indicated that Age Class 1 and 2 krill between 9 and 30 mm dominated the catch in the spring and early summer. Salps were abundant on the surface in late spring (mid- to late December), but did not exclude the krill. Some of the reproductive events associated with breeding chro- nology 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 1.47 chicks creched per pair, representing a small decrease 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 1997. 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 OPP-96-32763 and is Palmer LTER Contribution 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. 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, 1996/97 in AMLR 1996/97 Field Season Report: Objectives, Accomplishments and Tentative Conclusions. J.Martin (ed). Southwest Fisheries Science Center. Smith, R.C., et al. 1995. The Palmer LTER: A long-term ecological research program at Palmer Station, Antarctica. Oceanography. 8, 77-96. 1996. Palmer LTER: Annual January Cruise for 1997 (PD97- 01). Antarctic Journal, this issue. Figure Legends Figure 1a: Air temperature [degC] (solid line) and water temperature [degC] (boxes) at Palmer Station for the 9697 season. Figure 1b: Surface chlorophyll [mg/m3] (filled diamonds), nitrate+nitrite [MM] (open squares), and silicate [MM] (filled squares) at Station E for the 9697 season. Figure 1c: Krill abundance [g/m2] (open circles) 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 9697 season. Table Legend Table 1a: LTER9697 Palmer standard sampling events include acoustics (bio-ac, Biosonics 120KHz), discrete sample for chlorophyll analysis (chl), conductivity- temperature-depth (ctd, Seabird), high performance liquid chromotography of phytoplankton pigments (hplc), instan- taneous growth rate (igr), targeted tow for krill (krilltarg, Furuno 50KHz), microscopic analysis of net plankton (net, >5 Mm), inorganic nutrient analysis (nuts), photosynthetically active radiation (par), phy- siological condition (phycon), microscopic analysis of picoplankton (pico, 0.5-5.0 Mm), particulate organic car- bon (poc), production photosynthesis vs irradiance (Ppi), primary production simulated-in-situ (Psis), profiling radiometer (prr, BSI), discrete sample for salinity analysis (sal), transparent exopolymer particles (tep). and standard zooplankton tows (trwl). Table 1b: Palmer LTER 1996/1997 Event Log Overview of 1996/1997 season by sampling week (see Baker et al, this issue, Table 1a, for definition of standard sampling week). Events include acoustics (bio-ac, Biosonics 120KHz), discrete sample for chlorophyll analysis (chl), conductivity-temperature-depth (ctd, Seabird), high per- formance liquid chromotography 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 larvae (phycon), microscopic analysis of pico- plankton (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), transparent exopolymer particles (tep). and standard zooplankton tows (trwl).