The Gauntlet of Macrocystis Microscopic Stages 



will be affected by light, water, motion, etc., that vary with season 



1. LAND ON SUITABLE SUBSTRATUM 



- avoid other Laminarians on way down 



- avoid branches of Articulated Corallines 



- avoid space settled by other species 



- avoid chemical inhibition by species 



7. PRODUCE SPORES 



6. GROW TO ADULT PLANT 



- avoid removal by water motion 



- avoid entanglement with own species 



- avoid competition with other species 



- avoid grazers 



2. DEVELOP INTO GAMETOPHYTE 



- avoid overgrowth and shading 



by other organisms 



- avoid grazers 



- small echinoids 



- gastropods 



- micro-crustarea 



- Patiria 



- avoid being buried and abraded 



by sediments 



t 



^ko" 



5. GROW TO JUVENILE PLANT 



affected by: 



- density of own species 



- density of other species nearby 



- developing canopy 



- grazers 



V 



3. Cf GAMETES LOCATE Q GAMETES 



- fertilize 



4. GROW TO MICROSCOPIC SPOROPHYTE 



- avoid overgrowth and shading 



by other organisms 



- avoid grazers 



- avoid sediments 



Figure 25. The gauntlet of Macrocystis life history stages, 

 affected by physical /chemical factors that vary in time. 



Survival will also be 



discussed, along with interesting and 

 innovative approaches to experimental 

 studies (e.g., Underwood and Denley 1984; 

 see Strong et al. 1984). This debate is 

 particularly germane to subtidal studies, 

 which are in a relatively early stage of 

 experimental work. 



This chapter focuses on the questions 

 asked and the hypotheses proposed 

 concerning the distribution and abundance 

 of Macrocystis , the studies that have 

 examined them, and the evidence for their 

 importance. Some of the studies mentioned 

 earlier in this review are more critically 

 examined for details of experimental 



design and the conclusions based on them. 

 Figure 26 outlines the factors commonly 

 cited as affecting one or more of the life 

 history stages of this species. Several 

 spatial and temporal scales are also 

 listed. Not all of these hypotheses are 

 presently capable of being assessed 

 experimentally in the field. Much of this 

 will require innovative techniques and 

 methods (for review of current methods, 

 see Foster et al. in press). 



Most subtidal researchers are 

 logistically constrained to working at 

 relatively local sites along one area of 

 coastline, and usually over a short time 



90 



