littoralis and Ectocarpus confervoides played a greater role in the 

 deeper zone (M) in June as compared with November. This was most likely 

 due to normal seasonal succession. Fucus vesiculosus , which is peren- 

 nial, dominated the middle zone (F) all year round. There were more 

 plant species in June at all stations, compared to November, and the 

 increase was similar in all vegetation belts (Table 7.3.1). At station 

 B, however, the change in species in the Cladophora belt was only one 

 third of the change at station G. Generally the number of species was 

 higher at station G. 



The plant biomass had increased in the area at all examined sta- 

 tions (Table 7.3.1). It is remarkable that at station B, the Cladophora 

 biomass was about double that of the two other stations analyzed (Table 

 7.3.3), but the increase from November to June was only about half of 

 that at station G (67% compared to 138%). 



The animal diversity increase was somewhat higher at the contam- 

 inated stations compared to the reference station. This was particu- 

 larly obvious in the Ceramium + Mytilus belt. The reason for this 

 increase in diversity is partly that species which were eliminated in 

 November had recolonized the area in June (Tables 7.3.1 and 7.3.2). New- 

 seasonal species also appeared at all stations. 



The animal biomass decreased at most sampling sites. The decrease 

 was drastic at station B (98% change) in the Cladophora belt due to the 

 disappearance of most of the Mytilus . The increase of biomass in the 

 Fucus belt (65% at station B) was due to recolonization by Mytilus . In 

 the other vegetation belts the change at the contaminated stations B and 

 D was approximately similar to the reference station G (Table 7.3.1). 



The percentage of vagile animal forms of the total abundance and 

 biomass in the different belts changed drastically at the contaminated 

 stations B and D (Fig. 7.3.3 and Table 7.3.4). Figure 7.3.3 shows the 

 percentage and biomass of dominating animals in the Cladophora (C) , 

 Fucus (F) and Ceramium + Mytilus (M) belts in November and in June. 

 Figure 7.3.3 and Table 7.3.4 show a recolonization by vagile forms. The 

 percentage of vagile forms had more than doubled in all samples from 

 stations B and D in June. At Station G, only 40% of the samples doubled 

 their share of vagile forms. 



151 



