150 



60 



60 



150 ( 



4SS5 



' <*$J "^ ^~ r 



60' 



30' 



0' 



30' 



60° - 



••••M.angustifolia Jj 



mill M.mtegrifolia 



— M.pyrifera I Una 



^ 



Figure 2. The geographic distribution of the species of Macrocystis (redrawn from 

 Womersley 1954). 



Besides geographic limits to distri- 

 bution, there are also limitations within 

 localities. Marine plants are depth 

 restricted. Early surveys using SCUBA 

 identified various zones similar to those 

 in intertidal regions (McLean 1962, 

 Neushul 1967, Aleem 1973; see Chapter 3). 

 Stylized diagrams of depth distribution 

 resulted in composite pictures, such as 

 those in Figure 3. Surf grass ( Phyllo- 

 spadix spp.) is often found in very 

 shal low subtidal areas, with another kelp, 

 Egregia menziesi i , also occupying the 

 turbulent inshore sites. Several kelps 

 may inhabit intermediate depths (4-15 m 

 deep). Macrocystis pyrifera does not 

 generally extend into very shallow water, 

 or to depths below ^ 20 m in the turbid 

 coastal waters. Figure 3 presents only a 

 crude picture of depth distribution. It 

 is interesting that there are no published 

 studies which have quantified both the 



abundances and depth distribution of con- 

 spicuous species of algae at different 

 sites in California. Such a sampling 

 program would result in a more solid 

 framework for posing hypotheses about kelp 

 forest dynamics, in much the same way that 

 good experimental intertidal studies are 

 based on detailed knowledge of the distri- 

 butions and abundances of organisms 

 (Dayton 1971, Connell 1972, Underwood et 

 al. 1983). 



1.3. KELP FOREST ECOLOGY 



Distributional studies should be 

 concerned with the numerical abundances of 

 plants of a species in different loca- 

 tions. A single plant of a species such 

 as Macrocystis may have a much larger 

 impact on the rest of the community than a 

 single understory kelp. Nevertheless, the 

 presence or absence of a kelp forest is 



