FISHERY BULLETIN: VOL. 82, NO. 1 



species present, copepods among the smallest 

 (Table 4). 



The number of species collected from all zones 

 totaled 114, but ranged from 51 to 75 for any given 

 month (Fig 1). When ranked by the mean monthly 

 abundance, 7 species were dominant (>100/kg), 23 

 were common (10-100/kg), 24 were uncommon (1- 

 10/kg), and 60 were rare (<l/kg). Crustaceans and 

 gastropods had the greatest species representation 

 with 63 and 36 species present, respectively. The 10 

 most abundant species within the canopy and bottom 

 and 9 of the top 10 species in the middle were crus- 

 taceans; of the 14 crustacean species represented, 6 

 were gammarid amphipods and 4 were harpacticoid 

 copepods (Table 5). 



Vertical Patterns of Distribution, 

 Abundance, and Sizes 



70 



60 



en 50 



- / A 



o 



UJ 

 Q. 

 CD 



40 



O 



oo 



2 



z 20 



10 



V / 



A-./N'" 



\ 



/ TV 





b— o 



• CANOPY 

 A MIDDLE 

 o BOTTOM 

 a COMBINED 



_l I I I I I I I I I I I I I I I I L_l 



JJAS0NDJFMAMJJAS0ND 

 1975 1976 



Invertebrate numbers and biomass (no./kg kelp, 

 mg/kg kelp) were greatest in the middle (6,900, 

 2,387) and bottom (6,143, 2,061) zones, lowest in 

 the canopy (2,599, 1,743; Table 3). Similarly, the 

 number of species was always lowest in the canopy, 

 intermediate in the middle, and highest in the bottom 

 (Student's £-test,P< 0.05; Fig. 1). 



Gammarid amphipods were the most important 

 taxon associated with Macrocystis, dominating the 

 invertebrate assemblage within each zone in terms of 

 numbers (34-60%) and biomass (34-68%; Table 3). 

 Twenty species were collected with fewer species 

 present in the canopy (11) than in the middle (16) or 

 bottom (18). 



Collectively, Microjassa litotes, Gitanopsis vilordes, 

 and Aoroides columbiae comprised 837c by number 

 of all gammarids in the canopy, 92% of those in the 

 middle, and 70% of the gammarids in the bottom. 

 The most abundant gammarid in the canopy was G. 

 vilordes (53.0%); M. litotes was most abundant in the 

 middle (49.0%) and bottom (33.8%; Table 6, Fig. 2). 

 Among the other gammarids present, Ampithoe plea 

 and Hyale frequens were much more common in the 



FIGURE 1. — The number of invertebrate species present in each of 

 the vertical zones. Many species are present in more than one zone. 

 Grand means (± width of 95%C.I./2): 26.7 ± 1.6(C), 33.0 ± 3.3 (M), 

 38.9 + 3.2 (B). 



canopy than in the lower zones, whereas Batea 

 transversa and Pontogeneia rostrata were abundant 

 in the bottom zone and uncommon in the canopy 

 (Table 6). 



Numerically, copepods formed a major portion of 

 the invertebrate assemblage (29-43%), but con- 

 tributed very little to the total biomass (3-6%; Tables 

 3, 4). Although numerous in all zones, copepods were 

 more abundant in the middle and bottom (Table 3, 

 Fig. 2). Most (88% by number) in the middle zone 

 consisted o{ Porcellidium viridae, Porcellidium sp. A, 

 and Tisbe sp. In the canopy and bottom zones, P. 

 viridae, Tisbe sp., and Scutellidium lamellipes 

 accounted for 89 and 92%, respectively. 



Mysids and shrimps were minor numerical com- 

 ponents of the assemblage (2-3 and 1-5%, respective- 

 ly), but formed major proportions of the invertebrate 

 biomass (7-19, 6-33%; Tables 3, 4). Each of the three 



Table 5.— The ten most abundant invertebrate species in each zone. Abundances are mean monthly values for the 19-mo study 

 (C = copepod, G = gammarid amphipod, M = mysid, O = ostracod, S = shrimp, E = echinoid |urchin|). 



58 



