follows the site descriptions (Section 

 3.4), and Chapter 5 examines in detail 

 current hypotheses about the causes of 

 variation within and among sites. 



3.3.1 Central California 



3.3.1.1 Greyhound Rock . The site is 

 located 25 km north of Santa Cruz, and 4 

 km south of Ano Nuevo Island (Figure 8), 

 the northern limit of large stands of 

 Macrocystis pyrifera . Although a few 

 small stands of Macrocystis occur to the 

 north, Greyhound Rock is presently a 

 Nereocystis luetkeana forest (Figure 9). 

 It has been surveyed a number of times 

 since 1976 (Yell in et al. 1977, Foster et 

 al. 1979a, b, Foster and Reed 1980, 

 Foster and Heine 1981, Foster 1982a). 



The substratum is composed of 

 mudstone ridges interspersed with sand 

 that terminate in a large sand plain at 

 ^ 20-m depth. The site is fully exposed 

 to northwest swells and the water is 

 generally turbid. At depths of 5-8 m 

 inshore of the Nereocystis forest, 

 the rocky ridges are covered with multiple 

 layers of foliose vegetation (especially 

 the red algae Botryoglossum farlowianum , 

 Polyneura latissima , and Phycodrys 

 setchel li i , and the brown Desmarestia 

 1 igulata var. 1 igulata ) , along with 

 scattered patches of the understory kelps 

 Dictyoneurum cal i form' cum and Laminaria 

 setchel 1 ii [L. dentigera in Abbott and 

 Hollenberg 1976, but see Druehl 1979). 

 The vertical sides of the ridges are 

 covered with various tunicates and 

 sponges, and the few red sea urchins 

 ( Strongylocentrotus franciscanus ) present 

 occur on the sides of ridges facing shore. 



Nereocystis occurs on the tops of 

 ridges at depths of 8-14 m. Beneath it 

 are sparse stands of the understory kelps 

 Laminaria setchel 1 ii and Pterygophora 

 cal ifornica , with foliose algae beneath. 

 The walls and ledges beneath the ridgetops 

 are dominated by red sea urchins, 

 encrusting coralline algae, sponges, 

 tunicates, sea anemones, and solitary 

 corals. Predatory sea stars ( Pycnopodia 

 hel ianthoides , Pisaster brevispinus , _P_. 

 giganteus , and _P. ochraceous ) are common, 

 as is the omnivorous bat star Patiria 

 miniata. 



Large, foliose algae are rare seaward 

 of the Nereocystis stand (below 14 m), and 

 the substratum is dominated by encrusting 

 coralline algae, barnacles ( Balanus 

 crenatus ) , sea anemones ( Corynactis 

 cal ifornica ) , red sea urchins, and sea 

 stars (especial ly Pisaster spp.). Fishes 

 at this site have not been studied. 



3.3.1.2 Sandhill Bluff . This site 

 is a Macrocystis pyrifera forest located 

 10 km south of Greyhound Rock (Figure 8). 

 The area is described in the literature 

 cited under Greyhound Rock above and in 

 Cowen et al . (1982). The rocky substratum 

 is relatively flat mudstone interspersed 

 with sand patches (Figure 9). In deeper 

 water (14 to 17 m) beyond the kelp forest, 

 rock terminates in an entirely sand 

 bottom. The kelp forest is in the lee of 

 a small point, and is thus 

 slightly protected from northwest swells. 



Macrocystis pyrifera forms a surface 

 canopy at depths between 6 and 14 m 

 (Figure 9). Along the inshore edge of the 

 forest where giant kelp is absent, the 

 bottom is dominated by foliose red algal 

 species similar to those at Greyhound Rock 

 but, at this site, these plants grow over 

 dense mats of bryozoans, sponges, and 

 tunicates. Where a surface canopy is 

 present, the algal understory is reduced. 

 Small Pterygophora cal ifornica and 

 Laminaria setchel 1 ii occur in widely- 

 dispersed patches. Factors affecting the 

 algal assemblage at this site are shown in 

 Figure 5. 



Understory algal cover is reduced 

 beneath the Macrocystis canopy. Sponges, 

 tunicates, and pholad clams are common, 

 but over 50% of the substratum can be 

 unoccupied rock. Red sea urchin abundance 

 is low (< 1/m 2 ), and individuals are 

 clumped in small crevices and depressions. 

 The sea stars Patiria miniata , Pycnopodia 

 hel ianthoides and Pisaster spp. are 

 common. 



Offshore from the giant kelp canopy, 



foliose red algal cover is greater and 



understory kelps are less abundant. The 



tube polychaete Diopatra ornata , the 



anemone Corynactis cal ifornica , and 



compound tunicates cover much of the 



substratum. Sea stars found under the 



canopy are common offshore, and the 



26 



