Bornholm Basin in the Baltic Sea; 3 transects during the cruise in July and August 1993 (55° 15.5'N, 15° 24.0'E - 55° 19.0'N, 15° 20.4'E; 55° 17.7'N, 15° 59.8'E - 55° 21.7'N, 16° 00.4'E; 55° 12.2'N, 15° 51.1'E - 55° 13.7'N, 15° 57.5'E); 1 transect in August 1994 (55° 13.9'N, 15° 58.6'E - 55° 17.8'N, 15° 52.7'E); 1 transect in September 1994 (55° 14.0'N, 15° 59.1'E - 55° 17.8'N, 15° 53.5'E); 1 transect in June 1995 (55° 14.1'N, 16° 07.6'E - 55° 20.0'N, 15° 57.7'E).

Salinity of the water column; Density of the water column; Temperature of the water column; Bathymetry and Elevation

The main aim of this project was to describe the vertical distribution of two species of scyphomedusae (Aurelia aurita and Cyanea capillata) and their co-occurrence with cod eggs in the Bornholm Basin. Samples were collected during the cruises on RV 'Baltica' in 1993, 1994 and 1995. During the 1993 cruise (22 Jul-07 Aug) three transects were chosen, and during the other cruises (17-28 Aug 1994; 01-09 Sep 1994 and 20-29 Jun 1995) one transect for each cruise was covered. Along these transects, stratified hauls with a Multinet were taken at a depth range from 0 to 80m (20-minute hauls, repeated five times in each 10-metre depth layer). The Multinet consisted of 5 nets of 0.25 m**2 opening and 300 microm mesh size; the last net could not be closed. The hydrological parameters were recorded with a CTD probe coupled with the sampler. During the 1993 cruise, when medusae constituted only a small part of the zooplankton sample, the whole sample was preserved in 4% borax-buffered formaldehyde. In this case, the measurements were carried out in the laboratory. Otherwise, medusae were counted (each species separately), measured (their total volume was registered) and then discarded. In 1994 and 1995, all captured medusae were counted and their diameters and volumes were measured. The alimentary canals of medusae were examined to determine the presence of cod eggs.

National Marine Fisheries Research Institute
Kollataja 1
Gdynia

81-332
Poland