7.2.2 Materials and method s 



Quantitative samples of the Fucus belt macrofauna were taken at 7 

 stations in an area 2 to It) km from the Tsesis. The locations of the 

 stations and the ship are shown in Fig. 7.2.1. 



Three of the stations (A, B and C) are located on the west shore of 

 the island Toro. I'hese were the she-res first hit by the oil spill, on 

 the day after the accident (October 27). 



The two stations D and E were reached by the oil after approxi- 

 mately 5 to 10 days, respectively. Stations F and G are both situated 

 within 2 km of the grounding place. F is located on the small island of 

 Talloren east of Tsesis . Although the oil spill during the first days 

 drifted towards that island most of the visible oil passed it on both 

 sides. Station G north of Tsesis was never visibly oiled but on some 

 occasions slicks drifted close bv . 



The samples were taken by the so-called plastic-bag method. A 

 diver slipped a plastic bag over a randomly chosen Fucus plant at the 

 selected location. The water was strained off and the bag with its 

 content of algae and animals was transported to the laboratory for deep 

 freezing. Five samples were collected on each sampling occasion. The 

 individual samples were later thawed and analyzed by standard methods. 

 Thus, the composition and biomass of the fauna, the distribution of 

 sizes, the growth of the algae, and other items can be studied. 



The preliminary results presently available are based on a first 

 inspection of 104 of the total 212 samples (Table 7.2.2.1). So far the 

 animals in these samples have been counted and classified into sys- 

 tematic groups. Arithmetic means of density of the normally most abun- 

 dant groups are given, whenever possible with 95% confidence intervals. 



During the first year following the spill Mytilus edulis were 

 collected for oil analysis at the same 7 stations. 



7.2.3 Preliminary results 



A drastic decrease of the total Fucus macrofauna took place along 

 the shore that was first hit by the oil spill (on October 27). During 

 the following two weeks the arithmetic means of the density figures were 



131 



