Figure 17. Common understory algae (layer 

 2 in Figures 3 and 6) found in kelp 

 forests. 



30 60 90 120 



% OF FALL, 1977 Macrocystis CANOPY COVER 



Figure 18. Relationship between Macro - 

 cystis canopy cover and upright (non- 

 encrusting) understory algal cover in 

 three kelp forests north of Santa Cruz. 

 Total understory algal cover exceeds 100% 

 as layering was determined. Macrocystis 

 canopy cover at each site was considered 

 100% in fall 1977. Cover at other times 

 is expressed as percent of this value. 

 Understory cover was not surveyed at a 

 Point Santa Cruz site in fall 1977. 



removed, they found that the greatest 

 recruitment of Desmarestia spp. and 

 Laminariales was in treatments from which 

 the branches of articulated corallines 

 were also removed. Clearances to bare 

 rock aid not increase recruitment of other 

 species, suggesting that it is the 

 branches themselves that inhibit 

 recruitment. This could be caused by 

 shading, by abrasion, by the presence of 

 sediment which may be trapped in the 

 articulated algae, or by small grazers 

 concealed in the branches. 



Other articulated corallines such as 

 Bossiella spp. are also common in kelp 

 communities, but little is known of their 

 effects on other species. It is likely, 

 however, that where these calcareous algae 

 are abundant, they also reduce recruitment 

 of other plants, especially Macrocystis 

 (Wells 1983). 



4.3.5 Encrusting Species 



Little is known about the effects of 

 encrusting species in kelp communities. 



Encrusting corallines (Plate 2A) of the 

 genera Lithothamnium and Lithophyl lum are 

 extremely common in subtidal habitats, 

 including Macrocystis forests (Abbott and 

 Hollenberg 1976). TFese plants occur from 

 the intertidal zone to depths below 100 m 

 in the subtidal zone, and appear as pink 

 to purple crusts on almost all surfaces 

 not occupied by other organisms. One 

 species, Lithophyl lum grumosum , may form 

 crusts up to several millimeters thick. 

 The encrusting stages of articulated 

 corallines are sometimes mistaken for 

 these species. Encrusting corallines in 

 kelp forests probably grow slowly, and 

 certainly may persist for long periods. 

 Many species of filamentous and foliose 

 algae may grow epiphytically on them. 

 Boulders covered by encrusting corallines 

 are frequently inhabited by juvenile 

 abalone, and in the laboratory, encrusting 

 corallines induce settlement of abalone 

 larvae (Morse et al. 1979). On the other 

 hand, these crusts can reduce recruitment 

 of some sessile animals (Breitburg 1984). 



54 



