Cruise inventory

RRS James Clark Ross JR19981216 (JR38)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS James Clark Ross (74JC)
Cruise identifierJR19981216 (JR38)
Cruise period1998-12-16 — 1999-01-12
StatusCompleted
Port of departureStanley, Falkland Islands (Malvinas)
Port of returnStanley, Falkland Islands (Malvinas)
PurposeResearch
ObjectivesThe Pelagic Ecosystem Studies Core Programme is aimed at understanding the processes generating variability in the South Georgia marine ecosystem, with a particular emphasis on interannual variation. JR38 was the fourth cruise in the programme series.

On departure from Stanley, the ship steamed to the head of a standard oceanographic transect just to the north of the Maurice Ewing Bank (MEB). The transect consisted of 22 hydrographic stations, 35 km apart. On each station, a CTD profile with water bottle samples was taken to generate profiles of standard physical characters and allow chemical analyses and the determination of chlorophyl concentration. Jigging for squid was also undertaken simultaneously. Zooplankton net hauls were used to characterise the zooplankton community on each station and a chlorophyll fluorescence profile was also obtained using an Aquapack system. On a number of stations, extra water and zooplankton samples were obtained for detailed
biochemical analyses. Between the stations two acoustic systems were operational, a SIMRAD EK500 echoounder was run integrating returned echo signals to 250 metres, and a passive hydrophone array to monitor whales.

In the vicinity of South Georgia, surveys of two mesoscale (80x80km) boxes consisting of 5 sets of paired transects were sampled. A towed undulating oceanographic recorder (UOR) was used to characterise the upper 150m of the water column and the EK500 was used to describe the distribution of krill and other acoustic scatterers. Underway chemistry and standard analyses of the surface water were also undertaken. A series of standard station activities of CTD, water bottle samples, RMT8 and zooplankton net hauls were carried out at on-shelf and off-shelf stations within each survey area. Experimental work on zooplankton grazing, excretion and development rates was also undertaken.

Most of the data were validated and calibrated at sea and are available for comparative analyses with data from the previous three seasons. The preliminary figures indicate that there are some significant differences from earlier surveys in both the physical and biological regimes.
Chief scientistInigo Everson (British Antarctic Survey)
ProjectPelagic Ecosystem Studies
Coordinating bodyBAS
Cruise reportRRS James Clark Ross JR19981216 (JR38) cruise report jr38.pdf — access key 'C' (0.17 MB) 
Ocean/sea areas 
GeneralSouth West Atlantic Ocean (limit 20W)
SpecificSouth Georgia, Maurice Ewing Bank transect
Data held at BODC 
Discrete samples 
41  CTD frame plus rosette samplerAmmonium and ammonia concentration parameters in water bodies
Silicate concentration parameters in the water column
Nitrate concentration parameters in the water column
Nitrite concentration parameters in the water column
Phosphate concentration parameters in the water column
38  Sample taken from ship's non-toxic supplyAmmonium and ammonia concentration parameters in water bodies
Silicate concentration parameters in the water column
Nitrate concentration parameters in the water column
Nitrite concentration parameters in the water column
Phosphate concentration parameters in the water column