Report of Activities
on the RVIB N.B. Palmer Cruise 02-02
This is the first report of the third broad-scale cruise of the U.S. Southern Ocean GLOBEC Program aboard the Research Vessel Ice Breaker Nathaniel B. Palmer. Two similar cruises took place last year (NBP01-03 and NBP01-04). The focus of this study is on the biology and physics of a region of the Antarctic shelf due south of tip of South America that extends from the northern tip of Adelaide Island to the southern portion of Alexander Island and includes Marguerite Bay. This cruise is a joint ship operation with the R/V L.M. Gould, which will be conducting process studies in the same geographic region.
We have two primary goals: to elucidate shelf physical circulation processes and their effect on sea ice formation and Antarctic krill (Euphausia superba) distribution and to examine the factors that govern krill survivorship and availability as food to higher trophic levels, including fish, seals, penguins, and whales. The work on this cruise will involve collecting data at a grid of 92 regularly spaced stations positioned nominally at 40 km intervals within the survey area. The station activities will involve the deployment of the CTD [to measure water column physical properties (temperature, salinity, and microstructure) and to collect water samples for nutrients, microzooplankton, phytoplankton], the towing of a variety of nets [to collect zooplankton, especially krill, and mid-water fish for studies of their distribution and abundance and for studies of their physiology and biochemistry], the deployment on an ROV [for under ice studies of krill distribution and behavior], and the collection of live zooplankton, especially krill, to study of material properties [sound speed contrast and density contrast]. The work on the cruise will also involve collection of data along the survey trackline between the stations. The along track activities will involve the towyoing of BIOMAPER-II between the surface and about 250 m [to collect multiple frequency (5) acoustic data from reverberation off water column animals, high resolution video data of individual zooplankton, and environmental data (temperature, salinity, fluorescence, etc.)] and the surveying of sea birds and marine mammals. Throughout the cruise a passive listening device (sonobuoy) will be deployed to listen to marine mammal calls and continuous measurements will be made of sea surface water properties, water currents (with ADCP), meteorological properties, and sea floor bathymetry (with SeaBeam). Attempts will be made to collect diet samples from the sea birds.
We left the port of Punta Arenas, Chile at 1100 hours on Tuesday, 9 April 2002 after an intensive week of cruise preparation, which went very smoothly thanks to the excellent preparations and assistance provided by the Raytheon Technical Support Group. There was a moderate wind and partly cloudy skies.
The course to the survey area (first station is at -65.6633ºS;
-70.6580ºW) has taken us east from Punta Arenas through the straits of
Magellan, then south along the eastern side of South America (Argentina),
through the straits of Maire, then nearly straight
south to the start of the grid. The distance from
Shortly after leaving port, we stopped at a nearby dock to
pick up the Cajun Cruncher, a small boat carried by the N.B. Palmer, which had undergone
some repairs in
During 10 April, we steamed along the eastern side of the
southern tip of
About 0100 on 12 April, we crossed the 200 mile limit and began making science observations taking XBTs at 10 nm intervals, and recording SeaBeam bathymetry and along track sea surface and meteorological data. We are currently about 350 nm north of Station 1 (position at 0900 is -60 24.757ºS; -65 02.414ºW) and making about 10 knots. The skies are cloudy as they have been the past two days.