culated using the formula: 



^2min(-?,^.^,.*) 



Z(^y + ^«) 



(Clifford and Stevenson 1975) 



where X jj = abundance of attribute i at entity j 

 and X ik = abundance of attribute i at entity k. 

 Based on these similarities, cluster analyses incor- 

 porating a flexible sorting strategy (P = -0.25) was 

 used to form station groups (L,ance and Williams 

 1967). 



Intertidal Results 



Sedimentary Environment 



Intertidal beach sediments at GN during the 

 1986-87 operational period were comprised of 

 medium sands (0.3 - 0.4 mm) which consistently 

 contained low amounts ( < 1%) of silt/clay (Fig. 

 2). At JC, grain size in 1986-87 ranged from 0.5 



- 1 .0 mm (coarse- very coarse) and silt/clay content 

 from 0.5 - 3.3% . Medium sands also predomi- 

 nated during this period at WP ranging from 0.4 



- 0.8 mm; silt/clay content at this station was also 

 low throughout the sampling period ( < 1%). 



In the operational period, sediments were gen- 

 erally coarser at both potentially impacted stations 

 (JC and WP) than during prc-operational years. 

 Higher grain size was first observed in .June 1985, 

 prior to any possible 3-unit environmental changes 

 that might influence grain size at our stations. 

 Sedimentary characteristics at GN from 1986-87 

 were consistent with previous years results, and 



with no discemable increase over 1986-87 com- 

 parable to that observed at JC and WP. 



General Community Composition 



Intertidal infaunal communities during 1986 and 

 1987 were dominated by oligochaetes at JC (68% 

 and 87%), rhynchocoels at WP (68% and 59%) 

 and polychaetes (70% and 60%) at GN, respec- 

 tively (Table 1). Polychaetes were the second 

 most abundant group, contributing 12-32% of 

 the fauna at JC and 26-34% at WP. Oligochaetes 

 accounted for only 5-6% of the total at WP and 

 rhynchocoels < 1 % of the total collected at JC. 

 At GN, oligochaetes were the second most abun- 

 dant group (21%) followed by rhynchocoels 

 (8-9%). 



Polychaetes generally accounted for over half of 

 the total species collected each year. Arthropod 

 species were nearly as numerous at JC as 

 polychaetes, although abundances of individuals 

 were usually low. Other major groups at this 

 station (e.g., molluscs, rhynchocoels) v/ere repre- 

 sented by few species. At both WP and GN, 

 numbers of mollusc and arthropod species were 

 low in 1986 and 1987. 



The general community composition at JC dur- 

 ing the 1986-87 operational period was typical of 

 that observed during the pre-operational study. 

 Oligochaetes dominated this community and ac- 

 counted for over 80% of the total organisms; 

 polychaetes were usually the second most abun- 

 dant group and accounted for most of the species. 

 At WP, total abundances of polychaetes in 1986 

 and 1987 were below the 1980-85 range; the num- 

 ber of oligochaetes at this station was also low 

 while that of rhynchocoels was near the high end 



64 



