cal ifornica throughout the range of 

 Macrocystis . B. elegans has nonpelagic 

 planulae, and studies by Gerrodette (1981) 

 indicated dispersal distance is less than 

 0.5 m from the parent, perhaps accounting 

 for the usually aggregated distribution of 

 the species. Fadlallah (1983) estimated 

 an average lifespan of 6-11 years for this 

 coral at Point Cabrillo in central 

 California, with mortality resulting from 

 overgrowth of young corals by other 

 sessile animals and from predation by 

 spider crabs. 



The hydrocoral Al lopora cal ifornica 

 (Plate 2F) usually occurs in deep water at 

 the outer edge of kelp forests or on 

 offshore pinnacles. Currents are stronger 

 and the water cleaner in such habitats, 

 perhaps providing reduced sedimentation 

 and necessary food (Gotshall and Laurent 

 1979). Van Blaricom (pers. comm. ) has 

 observed A. cal ifornica at depths less 

 than 10 m within a giant kelp forest where 

 currents were strong and the water clear. 

 Ostarello (1973) suggested sedimentation 

 and competition with other sessile 

 organisms for space as sources of 

 mortality in young colonies, and breakage 

 and abrasion as important to older 

 colonies. An encrusting species, A. 

 (= Stylantheca ) porphyra , is occasionally 

 also found in California kelp forests. 



A number of large (to almost a meter 

 tall), fan-shaped gorgonians are frequent 

 in southern California kelp forests and 

 reefs. Muricea fructicosa (Figure 19) and 

 M. cal ifornica are most common within kelp 

 stands, while the red Lophogorgia 

 chi lensis usually occurs in deeper water. 

 All of these feed on plankton, and usually 

 orientate perpendicular to the prevailing 

 currents or surge. M. cal ifornica can be 

 aged from rings in the base, and Grigg 

 (1975) used age-height relationships to 

 determine size-frequency distributions in 

 various habitats near San Diego. These 

 distributions, along with habitat data, 

 were then used as measures of habitat 

 suitability and stability for the species. 

 Breakage from storms and increased 

 sedimentation, burial, and abrasion were 

 the major causes of mortality. Grigg 

 (1975) suggested that increased 

 sedimentation from sewage outfalls led to 

 a reduction in the number of gorgonian 

 colonies at Palos Verdes, an area 



influenced by Los Angeles sewage discharge 

 and where other kelp forest organisms, 

 including Macrocystis , have also declined 

 (see Chapter 6) . 



4.4.2.3 Bryozoans (Ectoprocts) . 

 Bryozoans are found almost everywhere in 

 kelp forests, and on everything from solid 

 rock walls to delicate algal fronds. 



Woollacott and North (1971) listed 59 

 species collected near the bottom in six 

 geographical areas from Monterey, 

 California, to southern Baja California, 

 Mexico. Ten of these were considered 

 widely distributed. 



The encrusting Lichenopora 

 novae-zelandiae , Membranipora tuberculata , 

 and M. membranacea (Figure 6~) are 

 extremely common on algal blades, 

 especially those of Macrocystis . 

 Membranipora encrustations may cover up to 

 75% of the kelp blades at particular times 

 in particular forests, and can grow to 

 cover a blade almost completely in three 

 weeks (Wollacott and North 1971). Wing 

 and Clendenning (1971) found that blades 

 with nearly complete cover of bryozoans 

 required 50% higher light intensities for 

 growth than unencrusted blades. Dixon et 

 al. (1981) showed that plants near a 

 thermal outfall in southern California 

 were much more encrusted with Membranipora 

 than were plants in a nearby kelp forest. 

 Experiments demonstrated that blade loss 

 from Macrocystis was correlated with the 

 degree of encrustation, as blades tended 

 to break off easily when heavily fouled. 

 Predation on Membranipora by fishes may 

 also indirectly cause blade loss 

 (Wollacott and North 1971, Dixon et al . 

 1981). Fouling may be reduced on other 

 kelps by frond abrasion, and this form of 

 disturbance can have important effects on 

 the entire epifaunal community on kelp 

 blades (Fletcher and Day 1983). 



Two other bryozoans are common on 

 understory vegetation and/or on the 

 bottom: the arborescent Thalamoporella 

 cal ifornica , and the lacy, fan-like 

 Phidolopora pacifica . The latter serves 

 as habitat for numerous small gastropods 

 and crustaceans. J. cal ifornica may have 

 a biomass close to 300 g/m 2 [wet weight) 

 in some kelp stands, about 50% of the 

 total sessile animal biomass (Wollacott 

 and North 1971). 



57 



