HOBSON and CHESS: TROPHIC INTERACTIONS 



night. The nighttime middepth collections (n = 6) 

 took X = 5.8 L. dubia, and the nighttime near- 

 bottom collections (w = 6) took x = 9.5. We found 

 this species in tubes of cemented sand grains in 

 daytime dredge samples from sandy bottom 

 (Hobson and Chess in prep.). 



Isopods 



Isopods generally were absent from the water 

 column during the day, although the plankton 

 collections show that at least some juvenile and 

 female gnathiids (Figure 5R) are present. After 

 dark, however, a number of isopods occurred in the 

 mid-waters (Table 6). Paracercies spp., in par- 

 ticular, were numerous. Most of the specimens of 

 Paracercies were juveniles or females (Figure 5P), 

 and their identity remains uncertain. Based on the 

 occurrence of males, P. cordata is by far the most 



numerous species of this genus in the study area, 

 but at least one other is present. 



Gammaridean Amphipods 



Gammaridean amphipods were generally ab- 

 sent from the water column during the day, 

 although Gitanopsis vilordes, which lived prin- 

 cipally amid the dense surface canopy of the kelp 

 forest bordering the study area (Hobson and Chess 

 in prep.), was collected in small numbers (Table 7). 

 At night, however, we saw gammarideans 

 throughout the water column, and, with Batea 

 transversa (Figure 5S) predominating, they were 

 a major component of our catch in the nighttime 

 collections (Table 7). Batea transversa was 

 numerous during the day amid the low benthic 

 algae that floors most of the study area (Hobson 

 and Chess in prep.). 



Table 6. -Isopods collected in the water column, day and night. 



'Many of the unidentified specimens are juveniles, probably at 

 above. 



east many being of the species listed 



577 



