COYER: INVERTEBRATE ASSEMBLAGE WITH GIANT KELP 



LENGTH (mm) 



Figure 5. — Combined size-frequency distributions of copepods, 

 gammarid amphipods, mysids, and shrimps measured quarterly 

 from July 1975 through October 1976 for each of the three vertical 

 zones. Copepods were measured during 1 mo only because of their 

 small size and variability. After normalization (%), the distributions 

 of each taxon were weighted according to mean monthly abundance 

 to create the combined distributions. The numbers of each taxon 

 measured before weighting are (C, M, B): copepods (54, 54, 55), 

 gammarids (308, 323, 317), mysids (2,037, 2,625, 2,500), and 

 shrimps 1 1,896. 1,776, 1,561). Statistics determined after weighting 

 are displayed in the figure. 



Mysids are remarkably specific in habitat prefer- 

 ences. Clarke (1971) found 12-14 species of mysids 

 cooccurring in the kelp forests off San Diego and Baja 

 California, but only A. sculpta and S.pacifica were 



10 





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 1975 1976 



FIGURE 6. — Monthly variation in numbers and biomass of all inver- 

 tebrate taxa (combined) within each vertical zone. Each monthly 

 value for the canopy, middle, and bottom represents a mean of three 

 (June-September 1975) or five (October 1975-December 1976) 

 replicate samples. 



associated with the kelp fronds. Similar patterns 

 were observed at Habitat Reef, as both A. sculpta 

 and S.pacifica were present in large numbers within 

 the kelp fronds, but were rarely observed in Mac- 

 rocystis holdfasts or other algal habitats within or 

 near Habitat Reef (Hammer and Zimmerman 1979). 

 Hobson and Chess (1976) found a few individuals of 

 A. sculpta in the water column at night, but most 

 remained closely associated with the kelp which was 

 utilized as food. In contrast, S.pacifica migrated from 

 kelp fronds into the surrounding open water at night 

 to capture small plankton (Hobson and Chess 1976). 



63 



