forests, and many feed on detritus and 

 plankton. In turn, small crustaceans are 

 a major food of many kelp forest fishes 

 (Quast 1971d, Bray and Ebeling 1974, Coyer 

 1979, Laur and Ebeling 1983; see Section 

 4.5 below). Gammarid and caprellid 

 amphipods (Figure 19), mysids (Figure 14), 

 and isopods (e.g., Idotea , Figure 20) are 

 especially common on seaweeds, and 

 low-growing algal turfs containing high 

 densities of these animals are common fish 

 feeding areas, particularly for perches 

 (Bray and Ebeling 1974, Laur and Ebeling 

 1983). Coyer (1979) found gradients in 

 abundance and size of particular 

 crustaceans from the bottom to the canopy 

 on giant kelp plants, and suggested that 

 some size gradients may reflect size 

 selective predation by fishes. Many of 

 the small crustaceans migrate from the 

 substratum into the water at night. 

 These, along with purely planktonic 

 species, are discussed in Section 4.2.2 

 above. 



Hermit crabs, primarily the genus 

 Pagurus , are frequent in kelp holdfasts 

 (Andrews 1945, Ghelardi 1971), and mats of 

 articulated corallines and other dense 

 understory algae. They are generally 

 scavengers and eat considerable amounts of 

 algae (Morris et al . 1980). Little is 

 known of the ecology of these animals in 

 kelp forests, but they may be important 

 grazers, particularly on small or delicate 

 plants. Foster (pers. obs.) observed 



hermit crabs, trapped within cages over 

 fouling plates, completely remove a lush 

 growth of foliose algae in one week. 



1cm 



5cm Idotea sp. 



Spider crabs, 



other crabs and lobsters 



large Cancer spp. , and 

 found in kelp 

 forests are mainly grazers or predators, 

 but all may occasionally feed on detritus. 



A careful search of almost any 

 substratum in a kelp forest will also 

 reveal barnacles. They can completely 

 dominate newly exposed surfaces. Balanus 

 crenatus is particularly abundant in 

 central California, while _B. pacificus is 

 more common in southern California. The 

 large (over 10 cm in diameter) Q. nubilus 

 occurs occasionally along the entire 

 coast. 



frequently 

 of Balanus 

 on 



observe dense 



crenatus in central 



bare substrata and the 



understory kelps. They are 



upon by sea stars (Pisaster 



Figure 20. Common invertebrate grazers in 

 kelp forests. 



We 



settlement 



California 



stipes of 



often fed 



spp.) that will even ascend stipes to 

 feed. Hurley (1975) found that flatworms 

 were major predators on subtidal ]3. 

 pacificus . Sheephead ( Semicossyphus 

 pulcher ; see Section 4.5 below) also eat 

 barnacles in southern California (Cowen 

 1983), particularly on newly placed 

 artificial reefs where other prey may be 

 less abundant (Carter, pers. comm.). The 

 oceanic barnacle Lepas pacif ica may be 

 excluded from kelp forests by fish 

 predation (Bernstein and Jung 1979). 



4.4.2.9 Tunicates (Urochordata, 

 Ascidiacea) . Tunicates are extremely 

 abundant in kelp forests, forming multi- 

 colored coverings on walls and other 

 shaded areas. The solitary Styela mon - 

 tereyensis (Figure 19) is particularly 

 common, and often mixed with understory 

 algae. Rosenthal et al. (1974) observed 

 S. montereyensis being eaten by the sea 

 stars Pisaster giganteus and Astrometis 

 sertulifera , and the whelk Kelletia 

 kelletii . 



Among the many colonial species 

 (Plate 2C), the lobed, grey-pink 

 Cystodytes lobatus is abundant, and may 

 occur to depths of 200 m (Morris et al . 

 1980). This and other tunicates often 

 provide habitat for small worms, 

 crustaceans and clams, and are common prey 



60 



