During the baseline period, evenness (J) ranged from 0.4 to 0.8, numbers of species from 30 to 86 

 and individuals from 301 to 3,561. Values for J were generally highest at IN and most consistent at 

 GN (0.6 in every year); EF and GN had the most species and IN generally the fewest. The numbers 

 of species collected at EF, GN and JC increased from 1982 through 1985 when high numbers of species 

 were collected at all stations. The IN station had consistently had lowest mean numbers of individuals 

 in all sampling years. 



Quarterly values of species diversity from September 1979 to March 1986, for subtidal stations are 

 presented in Appendix IV. At all subtidal stations, H', S and J were generally highest in the September 

 or .June. At F.F, all diversity values in the three 1986 (September and December 1985 and March 1986) 

 were lower than similar periods for the last two years. Values of H' over the same period at GN were 

 slightly lower than 1985, but very comparable to previous years. Because of the high density of 

 Ampelisca spp. in the December IN collections, H' was lower than all previous observations, otherwise, 

 values were similar to previous years. At JC, all species diversity index components in 1986, were 

 similar to previous years. 



Cluster Analysis 



Cluster analysis, performed to examine spatial and temporal similarities among subtidal collections, 

 clearly illustrated the spatially distinct nature of the infaunal community found at IN (Group I), and 

 the strong spatial similarity among collections from EF, GN and JC (Group II) (Fig. 13). Within the 

 IN group (I), collections made in 1985 and 1984 separated from previous years due to a species 

 compositional shift. In each of the last two years, large increases in the numbers of ampeliscid arthropods 

 have occurred, together with a marked reduction in annelid number (particularly oligochaetes). 



Group II included all other collections and the primary cluster was subdivided into station groups 

 (A, n, C). Within each group, collections made during 1985 and 1984 linked at highest similarity 

 reflecting the area-wide abundance of oligochaetes and Mediomastus amhiseta. In addition, species that 

 have been traditionally dominant at subtidal stations were found in unusually high abundance in these 

 years. For example at FF, high densities of Lumhrineri.^ tenuis, Ampelisca verrilli and l.eploc/ieirus 

 pinguis occurred in each of the last two years, while at GN and JC, Tharyx spp. and Polycimjs eximius 

 were very abundant. 



40 



