lower growth rate for copepods was also indicated, but the total stand- 

 ing stock remained unchanged. 



4.2 Material and methods 



4.2.1 Sampling stations 



Two stations in the spill area (IV and V, see map, Fig. 4.1) were 

 selected for intense monitoring during the month following the spill. 



The area in which station IV was located was directly exposed to 

 surface oil slicks only once, when a minor slick, which had been re- 

 leased from the tanker on removal from the area on November 3, drifted 

 quickly by. In the area northeast of the grounding site, at station V, 

 large oil slicks occurred during the first week after the accident. 

 Even at the end of the investigation period minor oil slicks were seen 

 drifting in this area. 



Immediately after the grounding, zooplankton net hauls were taken 

 at a station close to the grounding site (station II). Bacteria were 

 also sampled once at stations II and III (October 31). 



Two stations, I and VI, enclosing the spill area, are regularly 

 sampled by the Asko Laboratory. The research programmes include all 

 parameters sampled in the spill area and thus data from these stations 

 could be utilized for reference. Lack of resources limited the sam- 

 pling, which unfortunately hampered statistical analysis of the results. 



The salinity in the impacted area varied between 6.6 and 7.0 /oo S 

 in the surface water and between 6.6 and 7.9 /oo S at 20 m depth. The 

 temperature in the water gradually decreased, from 8.4 C to 6.4 C at the 

 surface and from 8.4 C to 6.9 C at 20 m depth, from November 1 to 

 November 17. 



4.2.2 Methods 

 4.2.2.1 Phytoplankton 



Phytoplankton were collected with a plastic tube 20 m long, care- 

 fully avoiding surface oil films. All samples were preserved with 

 Lugol's solution containing acetic acid. Phytoplankton were counted 



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