Numbers of Species 



Quarterly mean numbers of species (no. /core) from March 1979 - March 1986 ranged from 1 to 

 10 at GN; 3 to 13 at JC; and < 1 to 9 at WP"(Fig. 5). As with overall community abundance, the 

 number of species was highest at JC, while at GN and WP numbers of species were similar. The 

 seasonal trend in the numbers of intertidal species was similar to that of density, being higher in 

 September and .June than in March or December. 



Abiotic variables used in the multiple regression models accounted for 60% (GN), 63% (.IC) and 

 62% (WP) of the total variation in species numbers. After removing this variation, no long-term trends 

 in species numbers were evident at any station since 1980. Plots of annual adjusted mean numbers of 

 species illustrated the stability of this community parameter during the monitoring period (Fig. 6). In 

 addition, t-tests of adjusted annual means identified significant interannual differences between the 1982 

 and 1984 values at JC; all other pairwise comparisons between years were not significant. 



Species Diversity 



Annual mean species diversity (H') over the study period ranged from 1.2 to 2.3, and evenness (J) 

 from 0.4 to 0.7 (Table 4.). The mean numbers of species and individuals included in diversity calculations 

 ranged from 6 to 17 and 97 to 580, respectively. On an annual basis, no consistent spatial or temporal 

 shifts in H' have occurred over the monitoring period. Other parameters (S, J, N), reflected spatial 

 differences in the structure of intertidal communities. For example, at GN and WP both the numbers 

 of species and individuals was generally lower than at JC. 



Quarteriy values of species diversity from September 1979 to March 1986 for intertidal stations are 

 presented in Appendix II. Highest values of H', S and J commonly occurred in September at all 

 stations. For the three sample periods in 1986, H', S and J attained historical low values in the GN 

 September and December collections. At JC, H' and J were low in December relative to previous 

 values of these indices. Given the temporal variation of diversity parameters at WP, the values in the 

 1986 collections were considered similar to previous years. 



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