at this station. Silt/clay content at EF has also become more variable following construction activities 

 in the area of the Unit 3 discharge cut. 



General Community Composition 



The 960 samples collected from the four subtidal stations from September 1979 - .June 1985 yielded 

 a total of 359 taxa and 193,956 individuals. On an annual basis, polychaetes and oligochaetes were the 

 most abundant organisms and collectively represented 77 to 91%, 88 to 92% and '58 to 96% of the 

 individuals at BF, GN and JC, respectively (Table 5). At IN, these groups were also abundant (23 to 

 82%), although arthropods were generally more abundant than oligochaetes. Arthropods usually ac- 

 counted for less than 10% of the individuals found at other stations. Molluscs and rhynchocoels were 

 common at FF, but generally represented less than 10% of the total organisms collected. 



Polychaetes frequently accounted for over half of all species collected (Table 5). On an annual 

 basis, the number of polychaete species collected typically ranged from 60 to 75 at all but IN, where 

 totals generally ranged between 40 and 50 species. Arthropods were the second most numerous species 

 group at all stations (20 to 40 species) followed by molluscs (15 to 3p per year/station). 



Quarterly total numbers of individuals and relative abundance for each major taxa collected at 

 subtidal stations from September 1979 to March 1986 are presented in Appendix III. Polychaete species 

 number and abundances were generally highest in either September or June. Although molluscs and 

 arthropods contributed substantially to the subtidal communities, there were no consistent seasonal trends 

 evidenced by these groups. In comparison to previous years, some changes in species composition were 

 evident during 1986. Higher numbers of arthropod species were recorded in September and December 

 samples at CjN and .IC than in previous years. At these stations, total species number in September 

 collections was also high when compared to previous years. At IN, the numbers of species in 1986 

 continued to increase. This trend began in 1985 after construction activities (in 1984) eliminated most 

 of the species in this area. In contrast, the numbers of species and individuals of all the major taxa at 

 E'/F were generally lower in 1986 than in the previous two years. 



29 



