AMLR 2004 Weekly Reports No. 1 and 2

18 January 2004

1. The U.S. AMLR Program accepted the Russian R/V Yuzhmorgeologiya as ready for the 2004 charter at 0800 on 7 Jan 2004 in Punta Arenas, Chile. Over the next three days, provisions, equipment and personnel were embarked, laboratories were set up, and instrumentation was installed and tested. The ship departed at 0900 on 10 January 2004 in route to the U.S. AMLR study area in the South Shetland Islands, Antarctica. Gale force winds were encountered while crossing Drake Passage delaying landfall at Cape Shirreff until late 13 January, approximately 18 hours behind schedule. A large number of grounded icebergs were encountered in the immediate vicinity of the Cape.

2. Due to the risk of damage by icebergs, only one out of three instrumented buoys was deployed along the western edge of the submarine canyon immediately to the east of Cape Shirreff. Instruments included a dual frequency echosounder (50 and 200kHz) and a 300 kHz acoustic Doppler current profiler. Communications with the buoy were established and data is currently being telemetered to the field camp. Additional buoys may be deployed later in the cruise if conditions permit. The buoys were designed by David Demer, FRD/SWFSC, and built by Derek Needham, Sea Technology Services.

3. Provisions, mail and personnel (W. Trivelpiece and D. Krause, SWFSC, and D. Torres N. and D. Torres C., Chilean Antarctic Institute) were transferred to the Cape Shirreff field camp on 14 January. Operations were hampered by weather and ice and several boatloads of building materials remained aboard the ship.

4. Ship transited to Admiralty Bay, King George Island and anchored in Ezcurra Inlet during the evening of 15 January. Provisions and mail were transferred to the Copacabana field camp and the Polish base Artcowski without incident. S. Corsolini, originally scheduled to disembark at Copacabana, remained aboard due to illness. Deteriorating weather precluded successful calibration of the shipboard acoustic system. Calibration will be accomplished later in the cruise and data adjusted accordingly. 

5. On 16 Jan a survey of bio-oceanographic conditions in the vicinity of the South Shetland Islands was initiated. The survey area consists of four strata: the West Area north of King George and Livingston Islands; the Elephant Island Area encompassing the northern portion of the South Shetland archipelago; the Joinville Island Area in the western portion of Bransfield Strait; and the South Area in the central portion of Bransfield Strait south of King George and Livingston Islands. Planned order of coverage will be the West Area followed by the Elephant Island Area, the Joinville Island Area, and the South Area. We have completed four transects, comprised of 13 stations in the West Area.

6. Krill, salps and other zooplankton. Plankton samples have been processed from 11 West Area samples. Modest numbers of Antarctic krill (Euphausia superba) were present in most of these samples with a total catch of nearly 500 individuals. Lengths generally ranged from 35 to 50 mm with median and modal lengths of 42 mm. These represent 2 and 3 year old krill resulting from the successful 2000-2001 and 2001-2002 year classes. The presence of a few spent females and infrequent larvae indicate that some spawning has taken place but the majority of mature females either have not yet mated or are in the early stages of ovarian development. The salp Salpa thompsoni, amphipod Thysanoessamacrura and copepods (Calanoidesacutus and Calanuspropinquus) have numerically dominated the catches. Presence of large numbers of the high latitude salp Ilhearacovitzai at one station north of Livingston Island suggests the influence of Weddell Sea water in the West area.

7. Krill biomass and dispersion. Mean krill biomass densities along the first 4 transects in the West Area ranged from 21 to 47 g m^-2, comparable to densities observed in this area last year. Krill were mapped along all transects with highest densities (over 2 kg m^-2) near the shelf break north of Livingston Island.

8. Phytoplankton. In conjunction with NSF Office of Polar Programs and the “Global Drifter Program” (NOAA), AMLR is conducting a study of surface currents in the study area and the influence of the Shackleton Fraction Zone (north of ElephantIsland) on the Antarctic Circumpolar Current in the Drake Passage. During the southbound transect from Punta Arenas, Chile, the first four of 20 drifter buoys to be released this month were deployed. Too few stations have been completed at this time to allow a description of phytoplankton biomass. In cooperation with D. Stramski and B.G. Mitchell (Scripps Institution of Oceanography), an integrated optics package (consisting of AC-9, Hydroscat, 2 aBetas, fluorometer, two transmissometers, PAR sensor, and CTD) has been successfully deployed. Also a free-fall Biospherical PRR-600 to measure upwelling and downwelling light spectra will be deployed, but rough seas for the past two days have so far prevented this from happening.

9. Oceanography and meteorology. A well-defined Antarctic Polar Front was observed during the southbound transit at 58ºS with the sea surface temperature dropping from 5.45ºC to 2.71ºC and a corresponding decrease in salinity. A sharp drop in atmospheric pressure (as low as 963 mb), at the beginning of the week (12 Jan) and towards the end of the week (17 Jan), was accompanied by strong northwesterly winds, averaging around 35-40 kt, gusting to 55-60 kt. After crossing the APF the air temperature dropped from 6ºC to a week average of approximately 1ºC. Too few stations have been completed at this time to allow a description of oceanographic conditions.

10. Predator diet studies. 4 Antarctic fur seal scats have been processed to date from collections at Cape Shirreff all containing krill. None of these scats contained squid beaks or otoliths.100 live krill have been sexed and measured for total length, carapace length and width analysis to determine if current regression equations are accurate. 12 milk samples have been processed for lipid extraction. Samples processed are being stored either as frozen or in scintillation vials. 

11. Bird and marine mammal observations. 34 species of seabirds have been observed since 11 Jan, when we entered the Drake Passage area. Since entering the study area, we have conducted approximately 51 hours of underway observations. Unusual species observed include Westland petrel, gray-backed storm-petrel, and Arctic tern. Blue petrels and Antarctic prions were highly conspicuous in the offshore waters of the West Area. The following marine mammals have been observed during the course of our surveys in order of abundance: cetaceans: humpback, minke, fin, and southern bottlenose whales; pinnipeds: Antarctic fur seal. The primary area of concentration of humpback whales (n=35, group sizes: 1-8) occurred ~25 km N of Cape Shirreff, Livingston Island. Since 14 Jan, Antarctic fur seals (n=21, group sizes: 1-6) have been observed in offshore areas north of Livingston Island only. In addition, 3 killer whales and a leopard seal were observed in Admiralty Bay.

12. Scientific party aboard includes:

R. Hewitt, SWFSC, chief scientist

A. Cossio, SWFSC, acoustics

V. Loeb, Moss Landing Marine Labs, zooplankton

A. Jenkins, SWFSC, small boats, zooplankton

R. Rowley, MLML, small boats, zooplankton

J. Reum, UCSC, zooplankton

M. Force, SWFSC, zooplankton, bird and marine mammal obs.

K. Chambers, SWFSC, zooplankton

S. Sessions, SWFSC, zooplankton

J. Warren,SouthamptonCollege, inshore survey and zooplankton

E. Daniels, MLML, zooplankton

D. Needham, STS, Cape Town, oceanography, ET support

M. Van Den Berg, STS, Cape Town, oceanography, ET support

C. Hewes, SIO, phytoplankton

D. Allison, SIO, phytoplankton

J. Ryan, SIO, phytoplankton 

J. Lipsky, SWFSC, lipid extractions and scat analysis

J. Santora, CUNY, bird and marine mammal observations

A. Bernick, CUNY, bird and marine mammal observations

S. Corsolini, University of Siena, Italy

Submitted by R. Hewitt