Table 6 Concluded . 



Species 



Common name 



Grazing effects 



Megathura crenulata 



Notoacmea insessa 



Colli sell a instabilis 



Ischnochiton 

 intersinctus 



Lepidozoma cooperi 



Tonicella lineata 



Cryptochiton stelleri 



Aplysia californica 



A. vaccaria 



PHYLUM ARTHROPODA 

 Idotea resecata 



\_. stenops 

 Paracerceis cordata 



Ampithoe homeral is 



A. rubricata 

 Cymadusa uncinata 

 Limnoria algarum 



Pugettia producta 

 Tal iepus nuttaVj i 



Giant keyhole limpet Minimally effects kelps; feeds on understory seaweeds 

 and ascidians. 



Seaweed limpet Found almost exclusively on Egregia menziesii ; grazes 

 fronds and causes severe weakening. 



Unstable seaweed Found on stipes of Laminaria spp. and Ptery - 

 limpet gophora ; no evidence of damage to plants. 



Very indirect effects; may graze algal spores. 

 Same as above. 



Found on encrusting corallines; effects as above. 

 Grazes on bottom; effects unknown. 



Lined chiton 



Gumboat chiton 



California brown 

 sea hare 



California black 

 sea hare 



Kelp isopod 



Pillbug 

 Kelp curler 



Gribble 



Kelp crab 

 Southern kelp crab 



Occasional grazing on bottom and portions of 

 kelp plants. 



Grazes on Egregia ; effects unknown. 



Found on Microcystis and Pelagophycus ; eats 

 holes in blades, causing weakening and providing 

 centers for infection. 



Found on Egregia . 



May derive nourishment from kelp, but no visible 

 damage. 



Rolls and cements edges of blades to form a sticky 

 web; likely feeds on blades. 



Same as above. 



Same as above. 



Burrows into holdfasts and may cause 

 considerable weakening. 



Mainly herbivorous; eats kelp and other algae. 

 Same as above. 



smaller species, the purple urchin J5. 

 purpuratus , also shares the west coast 

 distribution of Macrocystis . It can reach 

 very high densities in these feeding 

 aggregations, some 90/m 2 in places 

 (Leighton 1971). 



A relationship between the feeding 

 activities of species of large and small 

 sea urchins was also noted by Duggins 



(1981b) in Torch Bay, Alaska. Large 

 Strongylocentrotus franciscanus trapped 

 drift plant material which the smaller 

 species, S_. droebachiensis , seemed unable 

 to hold down by itself. It appears clear 

 for west coast Macrocystis communities, 

 however, that either S. franciscanus or S_. 

 purpuratus is capable of extensive grazing 

 on attached plants. 



63 



