Species Diversity 



Annual mean diversity (H ' ) of intertidal communities ranged from 1.39 

 at GN to 1.69 at JC (Table 4). At GN , both diversity and evenness varied 

 similarly over the four sampling periods. Both H' and S in 1983 were lower 

 than the three year average, while evenness remained generally constant. 

 At JC , all measures of diversity exhibited strong seasonal shifts; in 1983 

 both H' and J were lower than the previous three year mean while S was 

 higher. Diversity measures at the White Point station also varied 

 seasonally, and only S was within the previous three year averages. 



Table 4. Species diversity (»'), evenness (.1), and number of specie 

 (S) for each Millstone Intertidal station sampled In I9b3. 

 ranoe of means 1980 - 1982. 



1983 Annual Mean 1980-82 Range of 



nd Standard Deviation^ Annual Means 



1 .39 t 0.35 1.60 - 2.25 



0.48 i 0.12 0.39 - 0.h5 



8 i 1 11 - U, 



1.69 1: 1.09 1 .73 - 1.80 



0.39 1 0.19 ■ 0.46 - 0.49 



1.47 ? 0.11 1.19 - 2.07 



0.59 t 0.24 0.37 - 0.67 



- Standard Deviation calculated using quarterly collettlo 

 September, December, March and June. 



Diversity measures, during the last several years have remained 

 generally stable at all stations. Although S has varied, the species 

 contributing to this change were generally not among the more abundant 

 organisms and their presence or absence had little influence on the other 

 measures of diversity. 



Cumulative Species Curves 



Cumulative species curves of intertidal communities sampled since 1980 

 were plotted to compare the total species and the seasonal shifts in the 



22 



