EBELING ET AL: ANNUAL VARIABILITY OF REEF FISH 



Figure 2. — Clustering, by year (right number), of canopy (C) 

 and bottom (B) cinetransect samples of kelp-bed fishes filmed 

 each September in 1971-74 at mainland (M) and Santa Cruz 

 Island (I) study sites off Santa Barbara, southern California. 



study sites. Samples from within mainland or is- 

 land sites tended to be more alike than samples 

 between these sites, particularly for bottom as- 

 semblages. Samples from within tended to form 

 secondary subclusters nested in the principal ones 

 distinguishing canopy and bottom assemblages 

 (Figure 2), and within-site similarity values 

 tended to be higher than between-site values (Ta- 

 ble 2). 



As indicated by clusters (Figure 2) and similar- 

 ity values (Table 2), however, mainland and island 

 canopy assemblages were more difficult to distin- 

 guish than bottom assemblages. The mean ratio of 

 within- to between-site resemblance (/ or tau) was 

 comparatively large for arrays of canopy species 

 (Table 2), indicating that canopy assemblages 

 were only slightly more distinguishable between 

 sites than among years. This, and the fact that 

 variances of canopy similarities were relatively 

 large (Table 2), explained why the clusters of 

 canopy samples were poorly defined. What few 

 between-site differences in canopy samples pre- 

 vailed were due to greater numbers of kelp perch 

 and juvenile olive rockfish observed in the canopy 

 habitat of the island site, and of blue rockfish at 

 the mainland (Table 1). Island canopy samples 

 contained a few more species than mainland 

 canopy samples (Table 3, S), and the average 

 number of species per cinetransect (Table 3) was 

 significantly greater (Table 4) at the island. (The 

 significant year-site interaction as indicated in 



1000. 



CANOPY 



MAINLAND 



BOTTOM 



--I000 



-.100 



-.30 



-10 



ISLAND 



MAINLAND ISLAND 



-_2 



SPECIES SEQUENCE (MOST COMMON TO RAREST) 



Figure 3. — Abundance-diversity curves for 31 species of kelp-bed fishes from canopy and bottom assemblages in yearly samples filmed 

 during 1971-74 at mainland and Santa Cruz Island sites off Santa Barbara, southern California. 



367 



