FISHERY BULLETIN: VOL. 78, NO. 2 



MAINLAND 



SLAND 



Figure 4. — Offshore profiles (vertically exaggerated) at mainland (Naples ReeD and Santa Cruz Island (Fry's Harbor) study sites off 

 Santa Barbara, southern California. Off the mainland, broad sand and cobble flats (stippled) separate rocky outcrops (hatched) between 

 the shore and Naples Reef (highest outcrop), 1.6 km offshore. Off the island, the relatively steep rocky bottom meets sand within only 

 about 50 m of shore. 



Table 6. — Yearly means (±95% confidence interval) of diver 

 estimated underwater visibility and temperature measured 

 with each cinetransect in bottom-habitat samples filmed during 

 1971-74 at mainland and Santa Cruz Island study sites off Santa 

 Barbara, southern California. 



mean — to compare variability of these different 

 measures of different magnitudes (Sokal and 

 Rohlf 1969:62). Averaged among eight yearly 

 samples (four mainland + four island, sum- 

 marized in Table 3), CV's for counts per transect of 

 individuals and species in canopy samples (x = 

 75.5% and 36.97f ) were significantly greater than 

 corresponding values (61.1%, 29.0%) for bottom 

 samples (^tests, P<0.05). Expectedly, therefore, 

 the CV for species diversity (A) of canopy samples 

 was also significantly greater (x = 33.8% vs. 

 13.6%, approximate ^-test, unequal variances, 

 P<0.05). 



Yearly differences in mean fish and species 

 counts per transect (canopy and bottom) were 

 highly significant (Table 4). All one-way ANOVA's 

 revealed such differences (Table 4), and highs and 

 lows generally coincided between mainland and 

 island sites (Table 3). For example, counts were 

 generally high in 1972, low in 1973, and inter- 

 mediate in 1971 and 1974. Thus, most of the sig- 

 nificant differences between means were due to a 

 relatively abrupt decline from high counts in 1972 

 to low counts in 1973. The 1972 peak was most 

 pronounced at the mainland site, when 10 of 16 

 species had greatest abundances, vs. 7 at the is- 

 land (Table 7). Peaks of five species coincided: 

 Paralabrax clathratus, D. vacca, E. lateralis, S. 

 atrovirens, and S. mystinus. The only other coinci- 

 dent peak abundance was of S. serranoides in 

 1 973 . Despite the general correspondence between 

 sites of overall changes in abundance and species 

 number, however, significant year-site interac- 

 tions (Table 4) indicated notable exceptions. For 

 example, 1973 counts of individuals and species 

 were relatively high in the mainland canopy, but 

 low in the island canopy (Table 3). 



Wolda's (1978) measures of annual variation 

 revealed overall trends in species abundances 



370 



