ROSENTHAL. CLARKE, and DAYTON: ECOLOGY OF A STAND OF GIANT KELP 



persisted in August 1972. The oldest surviving 

 plant lived until July 1972, an elapsed time of 

 5 yr. During July 1967 this plant (number 1) had 

 18 living stipes (Table 2). The number of stipes 

 growing from this plant reached a maximum of 

 34 during May 1968; thereafter, the number of 

 stipes slowly decreased. Based on data derived 

 from the fixed quadrats, a Macrocystis plant 

 growing in this bed with 18 stipes is at least 



2 yr old. Therefore, by July 1972 plant number 

 1 was probably at least 7 yr of age. In addition, 

 three other tagged plants were believed to be 

 more than 5 yr of age at the time of their dis- 

 lodgement, and four of the Macrocystis that grew 

 up within the fixed quadrats were still alive after 



3 yr and 3 mo (Figure 6). 



Counting the number of living stipes on 

 selected Macrocystis plants does not necessarily 

 indicate the age of a kelp bed or ages of plants 

 within the bed. For example, the number of stipes 

 found on individual plants at Del Mar usually 

 fluctuated with the season and the condition of 

 the plant (Table 2). Most of the adult Macro- 

 cystis displayed a period during which each plant 

 maintained a maximum number of stipes, fol- 

 lowed by a gradual decline in the total number 

 of stipes. At some point in the life of a Del Mar 

 Macrocystis the plant no longer appears to be able 

 to actively support a peak number of stipes. 



FAUNAL ASSOCIATION 



Components of the Epifauna 



Within the study area 38 species of fishes were 

 sighted (Table 3), and 98 species of epibenthic 

 invertebrates have been identified (Table 4). 

 Many of the macroinvertebrates listed in the 

 table were rarely observed, but 39 were seen on 

 over half of the dives. A number of these species 

 were numerically uncommon in this area, while 

 other animals were infrequently seen because of 

 differences in activity periods. For example, the 

 gastropod Cypraea spadicea was rarely observed 

 in exposed positions during daylight hours, but 

 was one of the most abundant mollusks during 

 the three nocturnal surveys made in this loca- 

 tion. Of the 38 species of fish which we recorded, 

 20 species were collected in 1958 by Quast (1968a). 



Epibenthic Invertebrates 



Invertebrates considered in this study consisted 



Table 3. — A list of fishes observed in the kelp bed by Quast 

 ( 1968a) and during this study. + + signifies those species seen 

 in both studies; — signifies those species seen in our study, 

 but not reported by Quast (1968a). 



Anisotremus davidsoni (Steindachner) 



Alherinops alfinls (Ayers) 



Brachylstius Irenatus Gill 



Chromis punctipinnis (Cooper) 



Coryphopterus nicholsi (Bean) 



Embiotoca jacksoni Agasslz 



Engraulis mordax GIrard 



Girella nigricans (Ayres) 



Gymnothorax mordax (Ayres) 



Halichoeres semicinctus (Ayres) 



Heterostichus rostratus GIrard 



Hyperprosopon argenteum Gibbons 



l-lypsurus caryi (Agasslz) 



Leiocottus hirundo GIrard 



Medialuna calilorniensis (Steindachner) 



Oxyjulis californica Giinther 



Oxylebius pictus Gill 



Paralabrax clathratus (GIrard) 



Paralabrax maculatofasciatus (Steindachner) 



Paralabrax nebulifer (GIrard) 



Paralichthys californicus (Ayres) 



Phanerodon lurcatus GIrard 



Pimelometopon pulchrum (Ayres) 



Pleuronichthys coenosus GIrard 



Pneumatophorus diego (Ayres) 



Rhacochilus toxotes Agasslz 



Rhacochilus vacca (GIrard) 



Scorpaena guttata Girard 



Scorpaenichthys marmoratus (Ayres) 



Sebastes atrovirens (Jordan and Gilbert) 



Sebastes auriculatus GIrard 



Sebastes chrysomelas (Jordan and Gilbert) 



Sebastes rastrelliger (Jordan and Gilbert) 



Sebastes serriceps (Jordan and Gilbert) 



Seriola dorsalis (Gill) 



Sphyraena argentea Girard 



Torpedo californica (Ayres) 



Urolophus halleri (Cooper) 



+ + 

 + + 

 + + 



+ + 

 + + 

 + + 



+ + 

 + + 

 + + 

 + + 

 + + 

 + + 



+ + 

 + + 

 + + 



+ + 

 + + 

 + + 



of those species living along the sea floor that 

 could be counted without disturbing the under- 

 lying substratum. Visually and numerically con- 

 spicuous macroinvertebrates were selected for 

 study after data were collected on presence of 

 species and their relative abundance in 1967. 

 Of the 98 invertebrate species seen, only 14 

 species appeared to comprise the "characteristic" 

 assemblage of epibenthic invertebrates in this 

 kelp bed (Table 5). Characteristic epifauna were 

 those "species that were always seen and that 

 dominated the habitat, both numerically and in 

 terms of their demand and impact on it." (Fager, 

 1968). Table 5 lists the frequency of occurrence, 

 numerical density, pattern of distribution, and 

 habit of each of the 14 species. Because of the 

 importance of natural history information to an 

 eventual synthesis of the organization of the kelp 

 community, the following observations are pre- 

 sented for the 14 species. The species are dis- 

 cussed in order of their relative abundance. 



The most abundant and frequently encountered 

 epifaunal invertebrate in the study site during 



677 



