Date: Fri, 1 Feb 2002 19:36:02 +0800 From: Robin Ross Subject: LMG02-01 Palmer LTER week3 and final days LMG02-01 Palmer LTER Synopsis for Week 3 and final days (18 January to 1 February 2002) Activities during the last 12 days of the Palmer LTER (Long-Term Ecological Research) project's 2002 summer cruise were diverse. While at the southern extent of the summer study region we planned to get diet samples from the Adelie pengins nesting at Avian I, just south of Adelaide I. Diets of birds from the southern region would then be compared to those of penguins nesting in the Palmer Station area, 400 km to the north. However, for the first time since 1997 we were not able to reach either Avian or Ginger I. There was 10/10 pack ice and snow-covered brash surrounding these islands, making the zodiac trip to drop the researchers off at the island impossible. In fact, the penguins were able to 'walk' on this surface as if it were frozen solid. In lieu of sampling the diets of nesting birds, we undertook a search for Adelies either on beaches or on ice floes accessible to the researchers. On the 18th Adelies were located in the Faure Islands (to the south and east of Avian I) and their diets sampled. On the 19th diets of Adelies on the beaches of Jenny I (to the west and slightly north of Avian I) and ice floes north of Jenny I were sampled. As in previous years, we exchanged personnel with the British Antarctic Survey at Rothera for a day of scientific collaboration. The diet sampling on 19 January was undertaken that day. We also cross-calibrated the CTDs used by the two long-term seasonal programs, that of the Palmer LTER at the northern end and that of the British Antarctic Survey at the southern end of the summer study region, and did an additional CTD cast to better document the connection of the inner edge of our southern most transect line (the 200.* line) with the Rothera study site. In the evening, the entire ship was invited for a barbeque at Rothera and a brief but much appreciated performance by a 'local band'. The LM Gould departed Rothera at midnight, and returned to station work at the inner edge of the 200.* line on 20 January. Although we managed to complete three stations, the increasing winds and seas of a very strong low (961 mb) forced us to move into the lee of Adelaide and the inner shelf stations of the 300.* line on 21 January. Although heavy phytoplankton standing stocks throughout the grid had consistently clogged our fine meshed net, at the stations inside Marguerite Bay and on the inner edge of the 200.* line the combination of the heavy phytoplankton and the increasingly heavy seas created extra strain on our nets. Within a 3 day period three nets ripped beyond repair, and we had to make significant repairs to the last of the 2-M Metro nets with us on board. Fortunately those repairs held, and we were able to finish the rest of the 200.* line and the 300.* line by midday on 24 January. The PRR (Profiling Reflectance Radiometer) was used at every station until the last day of cardinal line sampling when one of the 4-pin connectors failed. The necessary part for the PRR was not available on board, so we were unable to obtain PRR data for the last few stations of the cruise. In lieu of Profiling Reflectance Radiometer (PRR) data, light estimations for stations 300.120, 300.140 and the final Palmer area stations were done with the CTD Photosynthetically Available Radiation (PAR) sensor. GUV and QSR daily surface PAR data was also collected throughout the duration of the cruise. At the end of the third week, we had completed the core stations on all 5 cardinal transect lines, and headed north toward our previously postponed work in the foraging region of the Adelie penguins nesting near Palmer Station. We had excellent weather for the two days of sampling and observations in the Palmer Basin region (25 and 26 January). The schedule included sampling the seasonal stations near Palmer Station, a standard high density (HD1) 10 km by 20 km grid, and a mini-grid whose location was based on position data from satellite tags (PTTs) placed on Adelie penguins nesting near Palmer Station. On 19 January PTTs were placed on 4 Adelie penguins. The mini-grid design was based on data received over the following several days, and encompassed 3-4 trips per bird, or about 1 trip/day/bird. PTT positions clearly show that the birds were mostly feeding to the southwest over deep water, and not within the HD1 grid. The mini-grid started from the southwest edge of HD1 grid, and ran in 13 5-km legs, first through a region where the birds did not appear to be feeding and then through the bulk of the PTT positions. Both grids included continuous observations of seabird presence and type of activity, the depth and density of aggregations of zooplankton from acoustic transects, and sampling of surface waters for chlorophyll and nutrients every hour. The seasonal stations and the mini-grid with its complement of 3 XCTDs were completed on 25 January, followed by a net tow in the region where crabeater seals had been observed. The HD1 grid with its complement of 5 CTD and 9 XCTD casts was completed on 26 January around midnight. We docked at Palmer Station at 0730 on 27 January. Cargo operations and transfer of the seasonal sampling teams back to Palmer Station went smoothly, and all enjoyed cross-town pizza at the station that evening. The LM Gould left Palmer Station at 1000 on 28 January as scheduled. During the transit north both XCTD and XBT probes were dropped across the fronts. The northbound crossing was extremely smooth, and the LM Gould arrived at the Punta Arenas dock at 0630 on 1 February. All the Palmer LTER research teams would like to thank both ECO and RPSC for their support and expertise throughout the cruise. Captain Verret and his crew were extremely helpful, and their skilled seamanship helped make our cruise a success. A special thanks goes from the S-016 / S-032 team to the MTs for their extra assistance with the FRRF and PRR, and to the ET/IT crew for data archiving help. The BP-028 team would like to profusely thank RPSC personnel for their invaluable assistance in mending nets (MPC R. Sleister, and MTs S. Alesandrini and P. Dal Ferro). We would not have been able to get our trawling functional again with the loss of only one station without their help. Many thanks to all! We have summarized a snapshot of preliminary results from the last half of the cruise. BP-021 (D. Martinson) - Hydrography (Rich Iannuzzi): Preliminary observations of the temperature and salinity data for the 2 southern most on-to-off shore transect lines (100 km. Apart) show the following features. Some of the coldest and freshest water of the cruise was noted on the 200.* line, the southern most line into Marguerite Bay. Values as low as -1.4 Degrees C and 33 PSU from the coast and out the mouth of the bay. The pycnocline got shallower as we headed offshore from the mouth of the bay. Deep, offshore maximum values were around 2 Degrees C and 34.7 PSU. The 300.* transect line, 100 km. North, was warmer and saltier, more like the three earlier transect lines to the north (400.*, 500.* and 600.*). The thermocline on this line was relatively constant in depth from on to offshore, but the halocline showed a slight deepening. The offshore maximum values on this line were only slightly colder and saltier. In general for the cruise, the on-to-off shore data varied more smoothly and consistently than the along shore data. BP-046 (D. Karl) - Microbial ecology and carbon flux (C. Carrillo): Higher then average oxygen concentrations (> 400 umoles/liter) were observed within Marguerite Bay and correlated with higher ectoenzyme activity (> 40 nmoles/hour). This is probably a result of the annual "Marguerite Bay bloom" that is observed every year. Concentrations and activities decreased with increasing distance from shore. BP-016/032 (M. Vernet, R. Smith) - Optics and Phytoplankton ecology (W. Kozlowski): Continuing measurements of primary production by simulated in situ deck incubations on the 300 and 200 lines showed similar patterns to those described for the 600, 500 and 400 lines. Production rates dropped off a bit more severely on these southern lines once at the *160 stations, and the highest daily production rate on the grid was seen on the inside of the 200 line at station with 4.1 gC/m^2/d. The lowest average production for the grid was seen on the 300 line, with only 0.2 g C/m^2/d measured. Chlorophyll a (chla) followed a similar pattern, with the highest chla levels on the grid seen in the inside stations of the 200 line and the lowest on the outside of the 300 line. Diatoms were consistently seen in all ring net samples. For the grid stations where PRR data was available, the deepest one percent light depth was seen at station 300.180 at 77 meters, and the shallowest at 200.-040 at 10 meters, though the one percent light level at Palmer B&E and 610.035 (high-density foraging grid) were similarly shallow. As of our arrival in the Palmer Basin on the 25th, all HPLC samples from the cruise have been processed, and the FRRF continued to function well throughout the cruise. All dissolved inorganic nutrient samples have been analyzed, and CHN and microscopy samples have been packaged for analysis in the US at the end of the 2001-2002 field season. BP-028 (L. Quetin and R. Ross) - Zooplankton ecology (R. Ross): We continued to catch both Antarctic krill and salps on stations on the southern two transect lines, with the maximum catch of Antarctic krill of 14 liters at the inshore station on the 300.* line. Gravid female Antarctic krill were found at the outer stations as was true of the northern lines, and spawning frequencies ranged from 6.25 to 24.0%. With the widespread occurrence of abundant krill we were able to meet our goal of two growth experiments and one spawning experiment per line to document spatial variation on our indices of secondary production. During both the mini-grid and the high density grid conducted with simultaneous seabird observations in the foraging region near Palmer Station, we noted both the depth and density of the aggregations seen. In both grids there were two types of aggregations detected. Aggregations below 100 m were generally not dense, were extensive horizontally, and were likely the year-old Antarctic krill. At shallower depths (50-80 m) larger krill formed denser and more oval aggregations. Net tows confirmed these observations. Sightings of foraging seabirds and marine mammals generally coincided with the occurrence of the shallower, denser aggregations (see BP-013). BP-013 (W. Fraser) - Seabird ecology (H. Geisz and B. Pickering): We diet sampled a total of 22 Adelie penguins in two days. Although we were only able to get 5 informative diet samples from 12 penguins in the Faure Islands, the 10 Adelies sampled near Jenny Island had all recently foraged. Penguins in both areas were primarily eating fish, though tiny (8-15mm) juvenile Euphausia and large, gravid female krill were present in diets of birds from Jenny I. Fish otoliths were collected for future identification of species eaten. Although we used foraging data gathered from Adelie satellite tags placed on birds breeding on Humble Island to plan the track of the mini-high density grid, we did not observe any Adelies during the transects. However, we did see several groups of Gentoo penguins feeding and traveling during both the mini- and standard high-density grid transects. Though Adelies were observed traveling during the high-density grid, we did not log any feeding. Whale and Gentoo feeding observations corresponded with acoustic information that indicated the presence of krill on several of the grid lines near the southwest edge of the high density grid. A final aloha from BP-046 (D. Karl and field team Chris Carrillo, Hoang-My Christensen , Anne Gasc, Paul Morris, Kyle Vanderlugt ). BP-046 signs off and wishes calm seas and eventful science to future Pal-LTER endeavors. Sent from the Southern Ocean by Robin Ross (Chief Scientist) and the Field Team Leaders (C. Carrillo, H. Geisz, R. Iannuzzi, K. Pelletreau and W. Kozlowski) of the Palmer LTER 02Jan cruise.