Palmer LTER, LMGould 03-01 25 January to 1 February 2003 Weekly SitRep No. 4 During the last week in January the focus of the Palmer LTER cruise was on operations in Marguerite Bay, south of Adelaide Island, and on stations along the southern most transect line routinely occupied in summer. We finished station operations with two stations inside Crystal Sound on Feb 1. On Saturday, 25 January, we arrived at Rothera, the British Antarctic Survey (BAS) base on Adelaide Island at 0800. With a personnel basket we exchanged personnel for a day-long cruise in the area. Since 1997 we have conducted this joint exercise to link the hydrography of the BAS seasonal time-series in Ryder Bay with that of the Palmer LTER mesoscale grid. We conducted a series of CTD casts in the channel south of Rothera, and cross-calibrated our instruments. Also, a field team composed of BP-013 personnel and assistants deployed a zodiac near Jenny Island, and worked their way back to Rothera (about 12 miles) taking diet samples from Adelie penguins. At the end of the day, the LM Gould and BAS personnel engaged in an oil spill exercise previously arranged by BAS with NSF. The LM Gould's role was to provide the reason for a drill, and to stand by to give assistance if necessary. The exercise was successful, and the Base Commander and Environmental Specialist were pleased to have the chance to test their team with a surprise drill. After the drill and dinner on board, LMG and BAS personnel joined forcers for an entertaining evening with a live local band, and a short act contributed by three members of the LMG science group. Over the next few days (Jan 26 and 27) we occupied a series of stations in Marguerite Bay, planning to use the information gained to chose a site for our third process station. On 27 January BP-013 personnel and assistants from both science and Raytheon were dropped off on Avian Island, an SPA, for activities ranging from seabird censuses to installing guano traps to diet sampling. During the ~ 16 hr they were on the island, the LMG moved to stations just outside the mouth of Marguerite Bay. The LMG experienced winds averaging 33 kts and sometimes higher, whereas those on Avian Island said that there was just a slight breeze! After picking the 'birders' up at around midnight, we proceeded to our chosen process site, a region just east of the Faure Islands where we had seen both elevated fluorescence and low pCO2 when we passed through the day after the Rothera visit. For this process site, we were looking for a station with higher phytoplankton biomass than the previous two process stations in order to compare water profiles and experimental results. For the last three days of the week we worked our way seaward along the 200 transect line, finally completing the 200.200 station in the late morning of 31 January. There were three deep stations (> 3000 m) at the end of this line, and the improved weather was appreciated during the long CTD casts. The next scheduled station was in the mouth of Crystal Sound, at the north end of Adelaide Island, and the transit there occupied the remainder of the day. On Feb 1 we occupied the two stations in Crystal Sound, closed up science operations, and were visited by King Neptune and his court. Those aboard who had crossed the Antarctic Circle without his permission were given special attention. We all then turned our attention to finishing up experiments and trying to put our results in the context of previous years. Support from Captain Verret and his crew and Raytheon staff members continues to be excellent. The following paragraphs give a few highlights of science results from the second half of the cruise. BP-013 - PAL-LTER Seabird component. (PI: Bill Fraser) Field Team: Brett Pickering, Heidi Geisz We maintained our transiting bird census counts as well as stationary censuses for each point sampled on the 400, 300 and 200 lines during these past weeks. Inshore surveys near Marguerite Bay had significant bird and mammal activity, including feeding behavior. As with the previous grid lines, we did not see many penguins feeding off shore this year. Adelie penguins hauled out on ice around Jenny Island were found in greater abundance this year making the diet sampling in that area very successful. We were able to obtain 7 diet samples, as well as survey Jenny Island for seabird activity. All samples contained krill, but in varying stages of digestion. Great weather and minimal brash ice along Adelaide Island allowed us to set foot on Avian Island this year. We were able to survey 7 small penguin colonies and place 4 satellite transmitters on Adelies (two female and two male). Additionally, we collected 20 Adelie penguin diet samples in the afternoon as candidates returning from the early afternoon foraging were easily obtained. Diet contents consisted mainly of fresh krill with a few samples that contained fish. BP-016/BP-032 - PAL-LTER Phytoplankton Ecology (PI: Maria Vernet)/ Optics (PI: Ray Smith) Field Team: Wendy Kozlowski (team leader), Jeffrey Bechtel, Erin Bostrom, Michelle Ferrara, Peter Horne, Lauren Rogers, Karie Sines, Adriana Veloza. During the second two weeks of the cruise, the phytoplankton ecology / optics group continued core sample collection and sample analysis. In addition, three more UV Simulated in Situ production experiments (UVSIS), one bacterial/phytoplankton uptake experiment and one microzooplankton grazing experiment at process station three, and nine more five and ten micron size fractioned chlorophyll profiles were all completed during these last two weeks of the cruise. Preliminary estimates of both primary production and chlorophyll a continue to show the onshore / offshore gradient seen on the 600 and 500 lines, with strong correlations between the two parameters. The 400 and 300 lines show less variation in production than the 600 and 500 lines, with euphotic zone levels averaging approximately 0.51 and 0.37 gC/m^2 respectively. Dissolved inorganic nutrient levels (phosphate, nitrate, nitrite and ammonia) appear consistent throughout the grid (as measured through the end of the 300 line), though silicic acid levels (at 25% light depth) on the 600, 500, 400 and 300 lines all show an inverse relationship to production. Comparison of these data to pigments will be done in the future. Euphotic zone depth measurements (0.5% of the surface light) varied from 50 to 104m on the 400 and 300 lines, which is roughly the same as was seen on the 600 and 500 lines. January 25th had the most Photosynthetically Available Radiation (PAR) on the cruise to date, with nearly five times the light as the darkest day (1/27). BP-028 - PAL-LTER Zooplankton and micronekton (PIs: Langdon Quetin and Robin Ross) Field Team: Robin Ross, Charles Boch, Michelle Fuller, Mike Homes, Emily Lindsey, Lyndon Valicenti, Matt Wright The relative and absolute numbers of Antarctic krill and salps in our catches changed as we moved south on the mesoscale grid. On the 600 and 500 lines, there were more than 400 salps per tow at 8 of 21 stations, whereas salp abundances were that high at only 1 of 27 stations at parallel shelf locations on the 400, 300 and 200 lines. In contrast krill numbers were higher on the three southern lines, with a strong on/offshore gradient. Salps were absent at the entrance and within Marguerite Bay, and krill numbers declined the further into Marguerite Bay we towed. There are two species within our catches that are characteristics of colder inner shelf waters, the ice krill and the Antarctic silverfish. We found ice krill at stations at the entrance and inside Marguerite Bay, as well as close to the continent in the Grandidier. Larvae of the Antarctic silverfish were found in high abundance at only a few locations, primarily just inside the mouth of Marguerite Bay. Juvenile and adult silverfish were only found just south of Adelaide Island, at the two stations occupied near Avian Island where diet samples were taken from Adelie penguins. Reproductive Antarctic krill continued to be in short supply, and spawning frequency in those females in the reproductive cycle very low compared to other years. Spawning did occur in females collected from the three southern lines, but the frequencies (5 on the southern lines) were only on the order of 1-2%, not the 10-12% found in austral summer 2002. We conducted 7 instantaneous growth experiments on the three southern lines, 2 with krill from the shelf break, 3 with krill from the inner shelf, and 2 with krill from the Marguerite Bay area. At Process Station 3, to the east of the Faure Islands, the ice krill dominated the euphausiid community. However with multiple tows we were able to collect enough Antarctic krill to conduct fecal pellet production experiments (one day, one near midnight) and to freeze animals for later pigment extraction. We also froze some ice krill for a comparative study. One foggy night, samples of live krill were collected 'in the dark' to preserve their eye function and sensitivity, and have been maintained in the aquarium aboard the LMG. We hope to return these live krill to collaborators stateside. BP-045 - PAL-LTER Microbiology & biogeochemistry (PI: Hugh Ducklow) Field Team: Hugh Ducklow, Gene Burreson, Leigh McCallister, Callie Raulfs, Mary Turnipseed We have been collecting samples for key microbial and biogeochemical properties along the grid: procaryote abundance and biomass, enzyme activity (alpha- and beta-glucosidase), bacterial production rates (3H- thymidine and leucine incorporation); oxygen, dissolved inorganic carbon (CO2), and dissolved organic carbon (DOC). Although most samples will be analyzed after the cruise, we have finished all the bacterial production rate measurements and processed data for the 200 through 600 lines on the main LTER grid. In general both tracers show patterns of increased activity all along the inshore third or so of the grid, with some indication of higher activity to the north. We are also collecting samples for non- LTER colleagues not aboard the vessel. We are incubating samples for determination of bacterial group-specific activity for David Kirchman (U- Delaware), using the Microautoradiography-Fluorescent In Situ Hybridization (Micro-FISH) technique. Samples were collected at Stations B,E and the four corners of the grid. We are also collecting Oxygen-17 samples for Matt Reuer and Michael Bender (Princeton) for estimating net primary production in the surface layer. Samples for mass spectroscopic analysis at Princeton were collected at every other station along the entire grid, and will also be taken during the return passage across the Drake.