HOBSON and CHESS: TROPHIC INTERACTIONS 



Figure 12.- An aggregation of senoritas, Oxyjulis californica, passes along the edge of a kelp forest during the day. 



perch were small, as noted above, whereas their 

 senoritas were relatively large (110-223 mm, i = 

 169). 



All 24 specimens (19-99 mm, x = 51) collected 

 during the afternoon as they swam in groups 

 above the sea floor were full of relatively fresh 

 prey, as ranked below: 



1. CALANOID AND CYCLOPOID COPEPODS (100: 68.7: 74.1) 



calanoids (75: 44.3: 43.8); cyclopoids, including Corycaeus sp. 

 and Oncaea sp. (67: 24.4: 30.3). 



2. BRYOZOAN LARVAE (58: 7.3: 4.3) 



cyphonautes. 



3. HARPACTICOID COPEPODS (42: 7.1: 4.8) 



Microsetella sp. (25: 3.1: 2.1); Porcellidium sp. A (8: 0.1: 0.2); 

 unidentified spp. (21: 3.9: 2.5). 



4. CIRRIPEDIAN LARVAE (46: 2.8: 2.8) 



cypris stage. 



5. GAMMARIDEAN AMPHIPODS (25: 1.8: 4.7) 



unidentified fragments. 



6. CLADOCERANS (21: 4.8: 5.4) 



Evadne sp. 



7. MOLLUSK LARVAE (46: 1.1: 1.0) 



veligers. 



8. FISH EGGS (4: 0.1: 0.3) 



unidentified. 



9. RADIOLARIANS(4:0,1: 

 unidentified. 



.0.1) 



With the likely exception of the gammarideans, 

 which were unidentifiable, all of the items in the 

 above list are organisms present in the water 

 column at the time these fish were feeding. 



Chromis pi/nctip/nm's—hhcksmith 



The blacksmith, which can attain a length of 300 

 mm (Miller and Lea 1972), is probably the most 

 numerous fish in the nearshore waters at Santa 

 Catalina Island. During the day it concentrated 

 along the seaward edge of the kelp forests, but 

 occurred in varying numbers in most nearshore 

 habitats, usually aggregated in the mid-waters 

 (Figure 13). At nightfall it sheltered among the 

 rocks, often considerable distances inshore from 

 where it spent the day. 



Other species of the genus Chromis are wide- 

 spread in tropical seas, where they are known to be 

 planktivores, e.g.: West Indies (Randall 1967); Gulf 



591 



