ANNUAL VARIABILITY OF REEF-FISH ASSEMBLAGES IN 

 KELP FORESTS OFF SANTA BARBARA, CALIFORNIA 



Alfred W. Ebeling/ Ralph J. Larson,^ William S. Alevizon,^ and Richard N. Bray'' 



ABSTRACT 



Assemblages of kelp- bed fishes that live in and about the kelp canopy or over the reef bottom were 

 censused by movie strips (cinetransects) every September from 1971 to 1974 at rock reefs off Santa 

 Barbara, southern California. Cinetransects provided an adequate and efficient way to estimate 

 species composition (order of relative or ranked species abundances), diversity, and numbers offish for 

 yearly comparisons between canopy and bottom habitats at mainland and Santa Cruz Island study 

 sites. Canopy assemblages were simpler and more variable than bottom assemblages. They differed 

 less in composition between sites. Between-site differences in fish assemblages reflected differences in 

 structural habitat between mainland and island. Variation in species composition was less among 

 years than between habitats or sites in the sense that site- and habitat-specific composition of 

 assemblages persisted in the course of significant yearly changes in counts of fish and species per 

 transect. Despite these changes, "annual variation," as measured by variance of year-to-year log,(, 

 ratios of numbers of 16 common species, was relatively small. Its size was characteristic of stable 

 communities in predictable environments. As a group, planktivores, which form dense aggregations in 

 midwater, fluctuated most in numbers. Perhaps fish responded directly to local changes in water 

 clarity, temperature, currents, and density of giant kelp. However, coincident changes in fish counts at 

 mainland and island sites indicated that these local environmental factors, which did not vary 

 accordingly, were not the only causes of annual variability in fish abundance. 



Off southern California, rocky reefs and beds of 

 giant kelp, Macrocystis pyrifera,h.arhor more than 

 125 species offish, almost 259c of the Californian 

 marine total ( Quast 1968b; Feder et al. 1974). Sub- 

 tidal reef-fish assemblages have been extensively 

 studied in the warm-temperate San Diegan 

 Faunal Region to the south of Santa Barbara 

 (Quast 1968b, c; Hobson and Chess 1976; Lim- 

 baugh^), and in the cool-temperate Monterey an 

 Faunal Region to the north (Miller and Geibel 

 1973; Burge and Schultz'^; Gotshall et al/). Except 



'Department of Biological Sciences and Marine Science Insti- 

 tute, University of California, Santa Barbara, CA 93106. 



^Department of Biological Sciences and Marine Science Insti- 

 tute, University of California, Santa Barbara, Calif.; present 

 address: MRC Research Center, 533 Stevens Ave., Solana Beach, 

 CA 92075. 



^Department of Biological Sciences and Marine Science Insti- 

 tute, University of California, Santa Barbara, Calif; present 

 address: Department of Biological Sciences, Florida Institute of 

 Technology, Melbourne, FL 32901. 



"•Department of Biological Sciences and Marine Science Insti- 

 tute, University of California, Santa Barbara, Calif.; present 

 address; Department of Biology, California State University, 

 Long Beach, CA 90840. 



^Limbaugh, C. 1955. Fish life in the kelp beds and the 

 effects of kelp harvesting. Univ. Calif. Inst. Mar. Resour., IMR 

 Ref 55-9, 158 p. 



^Burge, R. T., and S. A. Schultz. 1973. The marine environ- 

 ment in the vicinity of Diablo Cove with special reference to 

 abalones and bony fishes. Calif. Dep. Fish Game Mar. Resour. 

 Tech. Rep. 19, 433 p. 



for scattered observations and species lists 

 (Hewatt 1946; Quast 1968c; Clarke and Neushul 

 1967; Neushul et al. 1967; Alevizon 1976), how- 

 ever, virtually nothing is known of the structure 

 and annual variability of such fish assemblages off 

 Santa Barbara, which is at the northern end of the 

 San Diegan Region as defined by Hubbs (1960). 



Ebeling et al. (in press) analyzed Santa Barba- 

 ran assemblages of kelp-bed fishes sampled from a 

 variety of habitats and localities along the main- 

 land coast and across the Santa Barbara Channel 

 at Santa Cruz Island. The fish community was 

 assumed to comprise smaller groups of species 

 that tend to segregate among habitat types. 

 Photographic observations made throughout 1970 

 were used to resolve five such "habitat groups." A 

 group of "kelp-rock species" (e.g., garibaldi, //^'p- 

 sypops rubicundus, and California sheephead, 

 Pimelometopon pulchrum) was most abundant in 

 relatively clear water and dense kelp over high- 

 relief rocky reef. "Canopy species" (e.g., kelp 



■'Gotshall, D. W., L. L. Laurent, E. E. Ebert, F. E. Wendell, and 

 G. D. Farrens. 1974. Diablo Canyon power plant site ecologi- 

 cal study annual report July 1, 1973^June 30, 1974 In W. J. 

 North (editor). Environmental investigations at Diablo Canyon, 

 1974. Calif. Dep. Fish Game Mar. Resour. Admin. Rep. 74-10, 

 p. 199-305. 



Manuscript accepted October 1979. 

 FISHERY BULLETIN: VOL. 78, NO. 2, 1980. 



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