Palmer LTER, LMGould 03-01 11 January to 17 January 2003 Weekly SitRep No. 2 During the past week, the Palmer LTER team on board the ASRV L M Gould completed the stations on the 500.* transect line, including two additional stations off the shelf with CTD casts to ~ 3400 m. The stations were done in two segments, with a break due to a low pressure system and high winds that shut down operations on the shelf on 11 and 12 January. Fortunately we were able to work 3 stations in the Grandidier Channel and Lemaire Channels during those days. We also completed one high density grid, the second process station, and retrieved and redeployed the sediment trap. Unfortunately a major piece of equipment, the PRR (Profiling Reflectance Radiometer), was smashed beyond repair during a cast on 13 January. The PRR is more sensitive than the PAR ball on the CTD, and allowed us to do CTD casts and water bottle sampling based on percent light both earlier and later in the day. However, we believe that we will still be able to complete 4 stations on most days. On 15 January good weather allowed us to complete the first of two high density grids that are focused on the interaction of Adelie penguins with their marine environment during a period of high chick growth and associated high demand for food. This first high-density grid (HD1) starts near Palmer Station, and two visitors, Dr. Polly Penhale of NSF and Dan Grossman, a journalist doing a radio documentary, joined us for the day. As usual we conducted simultaneous seabird and acoustic surveys at 2.5 km resolution on a 10 km by 20 km grid. Five CTD casts to the bottom, three with vertical profiles of nutrients and pigments, were conducted at intervals across the grid. This year additional spatial resolution of the hydrographic characteristics was achieved with SeaCat casts conducted from 'Bruiser", the Mark V zodiac used by BP-016 for the seasonal sampling at Palmer Station. The 9 casts were done along the onshore/offshore edges of the grid. We thank two Palmer Station personnel, Doug Fink, the boating coordinator, and Barbara Watson, the instrument technician, for their assistance in getting 'Bruiser' and the SeaCat ready for the day. The site for our process station in the Grandidier Channel was chosen to be near a group of islands (Trundle Island and the north Pitt Islands) where penguin colonies had not been censused in recent years (1989 and 1984 respectively). A current census will be valuable for a comparison to the ongoing work with colonies near Palmer Station. The process station also included CTD casts with profiles of various water parameters (oxygen, dissolved inorganic and organic carbon, fluorescence, pigments, nutrients, microbial activity), in addition to experiments on bacterial and primary production, and microzooplankton grazing, and large volume water sampling for BP-045. Macrozooplankton grazers from net tows (Antarctic krill and salps) were assayed for condition and grazing activity. On 17 January, after reoccupying the seasonal time series stations at B and E near Palmer Station, we retrieved the sediment trap that had been in place since last January, and redeployed the new trap at its location about 50 nmi west of Palmer Station. Captain Robert Verret predicted that the trap would be visible 200 yards to the starboard, and shortly after the release message was sent, four yellow flotation hats appeared at the surface exactly where he had predicted. Liz Caporelli, our MPC, very ably organized and executed a safe and efficient trap turnaround. We have received outstanding support from both Raytheon support staff and Captain Verret and his crew. Both routine and extra support requests are handled quickly and efficiently, whether relatively small tasks such as enlarging the drain are for the large tank in the aquarium so that krill can be maintained in large numbers on board, or large tasks as the sediment trap deployment. All Raytheon support staff have been involved in collecting the hydrographic data. Special thanks are due to the ETs Fred Stuart and Martin Tomasz who run the software and send the files to Doug Martinson (BP-021) at Lamont-Doherty Earth Observatory, and the MST Jordan Watson who analyzes the salts samples. Below are individual reports on scientific activities and results from the field teams on board. 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 500 line this week. Inshore surveys had little more than the occasional south polar skua noted while, in conjunction with past observations, we had hundreds of birds circling the ship around the shelf break areas and deeper stations. Initial results of the high-density grid found penguins, mainly Adelies and Gentoos, feeding inshore. Though we observed very few feeding penguin groups, our observations did correspond with krill acoustic findings. We were surprised to find very few whales in the area, as they have been present around Palmer Station this year. The latter points on the grid had little more than Wilson's Storm Petrels to census. During the Grandidier process day, good weather and supportive Raytheon/ ECO staff facilitated a bird surveying foray in the Pitt Island area. We were able to census and map Adelie penguin colonies on eight islands, including Trundle Is. Additionally, we collected Adelie diet samples from Trundle for comparison with process station data collected on the research vessel that day. BP-016/BP-032 - PAL-LTER Phytoplankton Ecology (PI: Maria Vernet)/ Optics (PI: Ray Smith) PI Field Team: Wendy Kozlowski (team leader), Jeffrey Bechtel, Erin Bostrom, Michelle Ferrara, Peter Horne, Lauren Rogers, Karie Sines, Adriana Veloza. During the first week of the cruise, the phytoplankton ecology / optics group successfully carried out nearly all of their core collections and analyses. These include collection and preservation of samples for particulate organic carbon and nitrogen (6 to 8 per station), and delta 18O (one per station), analysis of discrete samples (6 to 13 per station) for chlorophyll as measured on a Turner Designs fluorometer, pigment analysis (6 per station) on a Hewlett Packard HPLC, inorganic nutrient analysis (6 to 13 per station) on an OI Analytical nutrient autoanalyzer, primary production measurements (24 hour, on deck incubations), and measurement of ambient light with two different types of Photosynthetically Available Radiation (PAR) sensors. In addition, during the two process stations, one experiment was carried out for comparison of phytoplankton production to heterotrophic uptake, and two experiments were completed to try to estimate microzooplankton grazing rates. Additionally, five "simulated in situ" experiments were completed to compare production levels of phytoplankton exposed to UV with those where the UV wavelengths were filtered out (UVSIS), four short term, photosynthesis vs irradiance (PI) experiments were completed, and four, five and ten micron size fractionated chlorophyll profiles were taken. Through station 500.060 on January 13, the Profiling Reflectance Radiometer (PRR) was cast at the start of each station to get light level depth data. After the demise of the PRR, light depths have been estimated using the PAR ball on the CTD rosette. Preliminary estimates of primary production show the typical onshore/offshore gradient that is commonly seen in this area during this time of year. Levels on the 600 and 500 lines averaged around 0.59 and 0.45 gC/m^2, respectively, through the euphotic zone, which is slightly lower than estimates of the same lines one year ago. Chlorophyll data follows the same onshore / offshore trend as seen in the production. Pigment data (also preliminary) from the 600 lines show evidence of cryptomonads through the 600.120 station, with diatoms and prymnesiophytes becoming dominant on the outside of the line. Euphotic zone depth measurements (0.5% of the surface light) varied from 60 to 107 meters, both seen on the 600 line (inside and outside, respectively). Our brightest day (data through 1/17) was the tenth, with over three times the light seen on the darkest day (1/12). 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 At each station we conduct two net tows with simultaneous bioacoustic transects to quantify the zooplankton and micronekton communities. The 2-M net fishes in the upper 120 m where we see most acoustic targets, whereas the 1-M net fishes the top 300 m and has a finer mesh. The relative dominance of the two common marco-zooplanktonic grazers varied both on/offshore and between the 600 and 500 lines. Salps were more often numerous at stations on the shelf slope and on the 600 line than on the inner shelf of the 500 line. Krill were found at all stations inside the shelf break, with 1- and 2-year krill dominating the catch. Both growth and molting (n=6), and spawning frequency and egg production experiments have been conducted with Antarctic krill. Mature females in the reproductive cycle are rare, this year and egg production rates very low, unlike the summers of 2001 and 2002. The timing of the pulses of primary production, partially a function of when sea ice retreats, was such that it appears little food was available in late November when female krill need food in order for the ovary to mature. Although growth increment data will be analyzed later, the intermolt period in the growth experiments conducted to date (2 associated with the process stations) ranges from 16 to 42 d, well within results from previous years. At the two process stations our focus has been to look at the recent grazing activity of Antarctic krill and salps (if present) with both pigment content analysis and fecal pellet production experiments. We are conducting experiments both day and night to document possible diel effects. Additional samples are being taken for a pilot study of detailed diet composition analysis, and will be analyzed in the home laboratory. From the results of the fecal pellet production experiments, however, Antarctic krill were feeding at higher rates at the Palmer Basin process station than at the one in the Grandidier Channel. BP-045 - PAL-LTER Microbiology & biogeochemistry PI: Hugh Ducklow Field Team: Gene Burreson, Leigh McCallister, Callie Raulfs, Mary Turnipseed Our component of PAL-LTER is collecting samples for bacterial biomass, production and enzyme activity; as well as key biogeochemical properties: oxygen, dissolved inorganic carbon and dissolved organic carbon. Samples have been obtained for vertical profiles at all grid line stations on the 600 and 500 lines thus far. Bacterial production observations, gained through on board analyses of 3H-thymidine and 3H-leucine incorporation rates, show a general decline from on- to offshore stations, with suggestions of an activity maximum at km 80-120, and also a north-south gradient. Oxygen titrations are yielding excellent, high quality data with good replication of duplicate samples. We have completed two process study stations, a north station at 600.060 (07 January) and a mid-grid station near Trundle Island in the Grandidier Channel (16 January). We collected large volume particle samples for lipid biomarker and stable/radioisotopic analyses at both stations, and collected samples for isotopic end member specification at Trundle Island (terrestrial organic matter, krill, DIC, DOC, penguin poop). Successful recovery of the PAL deep sediment trap is the cruise highlight thus far. The trap has been redeployed annually for the past 10 years and will now take a well- earned vacation before resuming collection next year. In its place we deployed a brand-new McLane Mark IV trap system in the same location. Thanks to Cara Sucher and Barb Watson (Palmer Station) who helped us stage for the cruise and delivered replacement supplies, MPC Liz Caporelli for organizing and successfully executing the sediment trap operation, Doug Masten (Scripps) for timely assistance on the Winkler Hotline; to Bob Kluckhohn (RPSC) for the last minute trap acquisition, Dave Karl and Chris Carillo for much advice and guidance, and Capt Verret and the officers and crew of the LMG for getting us out here and keeping us warm, well- fed and on schedule.