Number of Species 



I'he number of species ranged from 2 - 9/core 

 at GN, 4 - 12/core at JC and from 1 - 6/core at 

 WP during 1986-87 (Fig. 5). Highest numbers 

 were more frequently found at JC, while values 

 at GN and WP more were similar to each other. 

 At all stations, species number generally mirrored 

 community abundance. An exception to this was 

 June 1987, a period of low species numbers but 

 high density (due to oligochaetes). The number 

 of species collected at WP was generally low dur- 

 ing 1986-87 and 4 of 8 values obtained since Sep- 

 tember 1985 were near the lower end of the range 

 established since 1980. 



The multiple regression analysis removed 48%, 

 74% and 47% of the variation in species number 

 from 1980-87 at GN, JC and WP, respectively. 

 After removing this variation, there were no trends 

 in species numbers at any of the intertidal stations 

 (Fig. 6). Year-to-year comparisons (t-tests) indi- 

 cated that species numbers at GN in 1987 were 

 significantly higher than in 1986, but neither year 

 was significantly different from those before 1985. 

 At JC, the 1986 value was significantly higher 

 than only 1982 and at WP, 1986 was significantly 

 lower than 1980, 1981 and 1984. Number of spe- 

 cies at tills station in 1987 was not significantly 

 different from any previous year. 



Community Dominance 



Oligochaetes dominated the macrofaunal com- 

 munity at JC, averaging 195/core and 309/core in 

 1986 and 1987, respectively (Table 2.). This taxon 

 was also the most abundant organism in each of 

 1980-85 sampling years as refiected by the high 

 BIV (100%). Scolecolepides viridis {15 - 35/core) 

 and Hediste diversicolor (20 - 29/corc) were the 

 next most abundant taxa at JC during the oper- 

 ational period. These species also had high BIV's 

 during the pre-operational and operational sam- 

 pling periods. Capitella spp. and Polydora ligni 

 ranked 5th and 6th in 1986-87 and although they 

 occurred in much lower abundance than the top 



three taxa, they have generally ranked similarly 

 among the dominants in past years. 



At WP, rhynchocoels, Paraonis fulgens, 

 flaplosco/oplos fragilis and oligochaetes numeri- 

 cally dominated during the 1986-87 period and 

 were also dominant during the previous 5 years. 

 Rhynchocoels were more abundant in the last 

 two sampling years (16 - 17/core) than during the 

 pre-operational period (13/core). This taxon was 

 the most consistently dominant organism (high 

 BIV's) during both the pre-operational and oper- 

 ational sampling periods. Other dominant species 

 at WP during 1986-87 were collected in lower 

 densities than 1980-85, although most were within 

 range of previous years. Except for SlreplosylUs 

 arenae, the position of these species among the 

 dominants was similar to that observed during 

 the pre-operational period. 



Five taxa (oligochaetes, Uaploscoloplos fragilis, 

 Scolecolepides viridis, Paraonis fulgens and 

 rhynchocoels) dominated the GN community. 

 Tliese species were also the predominant organ- 

 isms during the 1980-85 sampling period, although 

 the rank order differed. Relative to the pre- 

 operational period, rhynchocoel abundance in 

 1986 and 1987 was generally low as shown by 

 their lower position among the dominants. Other 

 than rhynchocoels, dominant taxa were found in 

 abundances that were generally higher than the 

 average over previous years, although their rank 

 among the dominants was similar. 



At all stations, there were some changes in the 

 organisms that occurred among the ten numerical 

 dominants during 1986-87 when compared to the 

 previous 5 years. Additions or deletions typically 

 involved taxa that exhibited large fluctuations 

 from year to year and thus had low BIV's. During 

 the operational period, four species at JC and 

 WP, and two at GN were among the top ten for 

 the first time. At JC, Fabrica sahella was collected 

 in high densities (10/ core) in 1986. At WP and 

 GN, species among the top ten for the first time 

 in 1986-87, were rare ( < 1/core). 



Benthic Infauna 



69 



