using the Utermohl (1958) technique. Small cells (<10 (jm) , with 1-4 

 flagellas, belonging to Chrysophycea , Cryptophycea and Chlorophycea we ± 

 counted collectively and are referred to as monads. 



4.2.2.2 Primary production 



Water samples were collected, while carefully avoiding surface oil 

 films, and incubated for four hours at 0, 1, 2, 4, 6, 8, 10, 15, and 

 20 m depth. Dark bottles were incubated at and 20 m depth. Measure- 

 ments were carried out as described by Larsson and Hagstrom (1979). 



14 

 Four (jCi of carrier free NaH CO were added to all bottles. After 



incubation, 10 ml of the samples were transferred to scintillation 



vials, and counted in Instagel (Packard Instruments) in an Intertech- 



nique SL 40 liquid scintillation counter. The uptake of carbon was 



calculated according to Gargas (1975). 



4.2.2.3 Bacteria 



Bacteria were sampled at a depth of 2 m using a sterile Niskin 

 water sampler. At reference station VI the number of bacteria was 

 determined in an integrated water sample (equal aliquots of water from 

 0, 5, 10, 15 and 20 m were pooled - a standard procedure in the routine 

 programmes at these stations (see Hagstrom et al., 1979). The bacteria 

 were preserved in formaldehyde containing acridine orange and counted in 

 an epif luorescence microscope, as described by Hagstrom et al. (1979). 

 They also described the method used for determining the frequency of 

 dividing cells (FDC). 



4.2.2.4 Zooplankton 



Zooplankton was sampled by vertical net hauls from bottom to sur- 

 face, using a UNESCO WP-2 net with 90 |Jm mesh size. Special efforts 

 were made to avoid contamination from surface oil films. The samples 

 were preserved in 4% formaldehyde buffered with hexamine. Counting and 

 species determination were performed using an inverted microscope. 



64 



