Date: Thu, 24 Jan 2002 22:04:54 +0800 To: mo-sciweekly@polar.org From: Robin Ross Subject: LMG02-01 Palmer LTER week 2 -- LMG02-01 Palmer LTER Weekly Synopsis 2 (11 - 17 January 2002) The second week of the Palmer LTER annual summer cruise was scheduled to include (1) all stations on the 500.* transect line (running offshore from the northern tip of Renaud I), (2) the high -density grid within the foraging range of the Adelie penguins nesting near Palmer Station with two net tows in the region, and (3) all stations on the 400.* line (running offshore from the southern tip of Lavoisier I). After finishing all 9 stations on the 500.* line, we did a station just inside the ice edge in the Grandidier. Of interest was the observation of 50-cm diameter pancake ice in between ice floes covered with snow. The LM Gould moved well through the 10/10 ice as we headed toward the Lemaire after that station, although the snow and slush began to clog the seachest and was starting to interfere with the water supply to the experiments on the 01-deck. The entrance to the Lemaire was blocked with 10/10 ice and bergy bits, so we retreated and did a station just outside the ice edge at French Passage. Unfortunately our good weather did not hold, and we were unable to do the high-density foraging grid on 14 Jan as the poor visibility made penguin observations difficult. We rescheduled the high density grid for the end of the cruise, and transited to the inside edge of the 400.* line during the bad weather. From 15 - 17 Jan we did all 9 stations on the 400.* line and the outer 3 stations on the 300.* line (perpendicular to the middle of Adelaide I) before leaving for the scheduled day on Avian I at the southern tip of Adelaide I). Shipboard systems are operating well, and we are receiving outstanding support from both Raytheon personnel and Captain Verret and his crew. Preliminary results are available from stations occupied on the northern 3 transect lines of the study region during the first 10 days of the Palmer LTER annual summer cruise. These transect lines are 100 km apart. The results were compiled by the field team leaders and their teams. BP-021 (D. Martinson) - Hydrography (Rich Iannuzzi): Temperature and salinity contours for the northern 3 on-to-off shore sample transects show the following features. The temperature minimum is at about -0.5 degrees C or slightly colder and generally shallower offshore (~75-100 db.) One exception is the water off of Palmer station to 100 km. which has a bit warmer (~0.0 degrees C) and shallower (~60-80 db.) temperature minimum. The temperature maximum is warmer and shallower offshore with a value of ~2 degrees C at a pressure of 300 db. The salinity contours show similar patterns. The base of the halocline shallows as we head offshore, with an exception off of Palmer station where it deepens. There is deeper, saltier surface water from north to south. BP-046 (D. Karl) - Microbial ecology and carbon flux (C. Carrillo): Dissolved oxygen , dissolved inorganic carbon (DIC), total alkalinity (TA), dissolved organic carbon (DOC), lipopolysaccharide (LPS), leucine uptake and ectoenzyme activity (leucine aminopeptidase; LAPase) are currently being sampled in the water column. Experiments are also being conducted to determine net community oxygen production and respiration. These measurements will be compared to electron transport system (ETS) activity, after being normalized to adenosine triphosphate (ATP) concentrations throughout the water column. Bottom moored sediment traps, which have been deployed for approximately a year, have been recovered and re-deployed. A visual inspection of sediment trap samples suggest a low particulate matter flux with no indications of any major flux events throughout the year. Initial analysis of oxygen concentrations show surface waters range from 344 to 444 umoles/liter with higher concentrations found inshore, especially within Marguerite Bay. Concentrations decrease with depth to an oxygen minimum zone located at approximately 200 meters. Concentrations at the oxygen minimum depth range from 171 to 201 umoles/liter. Enzyme activity is higher when compared to measurements made within the same region 3 months ago. Activities range from 3.00 to 30.73 nM/h. While enjoying the cruise Team BP-046 (Chris Carrillo, Hoang-My Christensen , Anne Gasc, Paul Morris, Kyle Vanderlugt) is looking ahead to finishing its final year of sampling before signing off from the Palmer-LTER group. BP-016/032 (M. Vernet, R. Smith) - Optics and Phytoplankton ecology (W. Kozlowski): Preliminary estimations of primary production (BP-016), as measured with on deck simulated in situ incubations, along the first three lines show the typical onshore/offshore gradient seen in past seasons. Relatively elevated production, extended through the *.140 stations in all three lines, and highest production on the cruise to date was seen in the inside of the 600 line. Average production varied from 0.68 gC/m^2/d on the 600 line to 0.53 gC/m^2/d on the 500 line. The 400 line measured only slightly higher than the 500. Additional samples have been collected and processed at all stations for pigments (HPLC) and dissolved inorganic nutrients, and collected and preserved for later analysis of particulate organic carbon and nitrogen, and microscopy. The FRRF (Fast Repetition Rate Fluorometer) has been deployed at all stations sampled thus far. Early inspection of water samples collected with a 5 micron ring net show an abundance of larger diatoms, particularly Corethron sp., Chaetoceros sp., and Thalassiosira sp. Samples have also been analyzed for chlorophyll a (BP-032), and the data show similar trends to those seen in the production data. The PRR (Profiling Reflectance Radiometer) has been deployed at all stations as well and has provided us with reliable light data for determining sampling depths. BP-028 (L. Quetin and R. Ross) - Zooplankton ecology (R. Ross): Antarctic krill were in high abundance on these northern lines, with 5 of the 30 catches containing more than 300 Antarctic krill per 1000 m3. The krill had been feeding well. The catch was dominated by small krill hatched in the summer of 2001, but also included mature females in spawning condition. The observed spawning frequencies (6 experiments so far) of 8-9% usually indicate a high reproductive output for the population, as was also found last summer. Although salps were found at most stations, they were only abundant at two deep stations off the shelf. In contrast to the last several seasons, the ice krill (Euphausia crystallorophias) occurred in high abundance within 60 km of the continent. BP-013 (W. Fraser) - Seabird ecology (H. Geisz): Penguins have not been abundant during observations this year in comparison to last year's data, especially when contrasting Chinstrap sightings. Chinstraps were observed on various stations of the 600-300 lines last year, yet on only two stations of the 600 line this year. 2 Gentoos and 14 Chinstraps were feeding at 600.100 to 600.120, corresponding with net tows containing an abundance of large krill. Our only observations of Adelies thus far occurred in transit from the Grandidier to French Passage where ~50 birds were on ice or traveling in groups. Other bird observations included primarily Cape Petrels, Southern Fulmars and Wilson's Storm Petrels, which were most often noted feeding beyond the shelf break. 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.