Table 1. Concluded. 



Factor Influence 



Toxic substances: 

 Cu Reduced Microcystis growth and reduced fertility at 30 ppb 



DDT Possible general alteration of community 



Diseases of: 



Plants Occur, but population effects? 



Urchins Can cause massive mortality 



Sea stars Occur, can cause massive mortality 



Fish Occur, but population effects? 



Grazing by: 



Fish Can destroy Macrocystis if plants at low density 



Sea urchins Can create areas of varied size nearly devoid of foliose macroalgae 



Isopods May destroy canopy and sub-canopy tissue 



Other grazers Consume small life history stages. Population effects? 



Predation Sea stars, sheephead, sea otters and other predators, including 



humans, may affect the distribution and abundance of a variety of 

 species 

 Sea stars and fishes may alter plant-sessile animal competition 



Competition Canopy shading inhibits understory algal recruitment and growth 



within and among species 

 Pre-emption of space 

 Whiplash effects of algal fronds 

 Competition for space and light affects distribution of sessile 



species 

 Competition (including behavior) affects fish distribution 



