BODKIN: MACROCYSTIS AND NEREOCYSTIS KELP FORESTS 



would be most evident at the sea floor and may in 

 fact have contributed to the observed differences 

 in densities in the bottom dwelling surf perch (Table 

 5). My data indicated that the major differences in 

 densities of fish were in midwater species, suggest- 

 ing that exposure to bottom disturbance per se was 

 not a primary influence on observed patterns. 



4) The differing physical characteristics of the 

 Macrocystis and Nereocystis plants themselves may 

 play a role in determining their suitability as habitat 

 for kelp bed fishes. During periods of full develop- 

 ment, within this study area, Macrocystis typically 

 has widely spaced, thick bundles of stipes with large 

 fronds throughout the water column, leading to a 

 canopy that is frequently closed. Nereocystis, in con- 

 trast, has single, frondless stipes with large terminal 

 fronds that generally form a broken surface canopy 

 (Fig. 1). Due to the distinct physical structure of 

 these two plants, both within the water column and 

 at the canopy, the foliage biomass is usually con- 

 siderably greater within the Macrocystis forest. This 

 abundance of structure, combined with its persis- 

 tance over time, may enhance the carrying capacity 

 of giant kelp forests compared with those of bull kelp 

 (Leaman 1980). 



A comparison of the standing crop estimates pre- 

 sented in this study is made with those from other 

 marine reef systems in Table 6. While values for 

 both Macrocystis and Nereocystis forests are below 

 those representing fringing coral reefs (Brock 1954; 

 Randall 1963), my estimates for Macrocystis forests 



compare favorably with the upper values obtained 

 in Monterey, CA (Miller and Geibel 1973) and north- 

 east New Zealand (Russell 1977), while the Nereo- 

 cystis estimate corresponds to the estimates from 

 Southern California Macrocystis forests (Quast 

 1968; Larson and DeMartini 1984). 



In conclusion, Macrocystis forests supported a 

 biomass of fish about 2.4 times greater than that 

 supported by Nereocystis forests (Table 4) where 

 perennial, water column foliage provided a more 

 persistant, structurally diverse habitat. Larger 

 numbers of midwater fish, primarily 5. mystinus, 

 found in the Macrocystis forest can account for this 

 difference. 



ACKNOWLEDGMENTS 



This work was supported by the U.S. Fish and 

 Wildlife Service, Denver Wildlife Research Center, 

 Marine Mammal Section. I thank R. Brownell, R. 

 Curnow, J. Estes, R. Jameson, C. Jones, M. 

 Layman, L. Rathbun, P. Vohs, and S. Wright for 

 their support. D. Hilger, D. Martin, F. Scott, M. 

 Shawver, and G. VanBlaricom contributed their 

 time as dive partners to this work. I would like to 

 thank the members of my graduate committee— A. 

 Roest (advisor), F. Clogston, R. Gambs, and R. 

 Nakamura— and staff— R. Bowker and L. Maksou- 

 dian, and the Biological Science Department, 

 California Polytechnic University, San Luis Obispo, 

 CA. Valuable comments on earlier drafts of this 

 manuscript were offered by P. Eschmeyer, R. 



Table 6.— Comparison of biomass estimates of fish from marine communities (after 



Russell 1977). 



'Average estimate. 



807 



