HOBSON: FEEDING RELATIONSHIPS OF FISHES 



Figure 5. — Shallow reef-flat habitat. Most of the fishes shown are acanthurids, and include Naso lituratus and 



N. unicornis. 



Pocillopora meandrina, growing as isolated heads 

 10 to 50 cm wide. The outstanding characteristics 

 of this habitat, which generally has a maximum 

 water depth of only about 3 to 4 m, are extreme 

 water movement and wave shock. The fishes listed 

 in Table 4 ^ are characteristic of those seen on 

 shallow reef flats during the day. 



^Table 4 is based on data from three transects at three shallow 

 reef-flat sites at Palemano Point (see Figure 1). Note: one of the 

 transect counts was aborted after 60 m when the surge became 

 too strong to continue. Total number of species observed on these 

 three transects: 54; mean number of individuals of all species for 

 a single transect: 578. 



Table 4. — The 10 fish species most frequently seen along trans- 

 ect lines in the shallow reef-flat habitat during the day. 



Reef-Face Habitat 



At the offshore edge of the shallow reef flats, and 

 at many locations along the shore, a sheer basalt 

 face falls precipitously to water depths of 10 to 15 

 m (Figure 6). This situation produces a wide range 

 of conditions within a limited area. In its upper 

 regions the surge and wave shock are that of the 

 reef-top habitat, but these rapidly abate with in- 

 creasing depth. Conditions adjacent to the base of 

 the reef face are essentially those of the boulder 

 habitat, with fragmented pieces of the reef lying 

 about as large boulders. The predominant forms of 

 benthic life, dotting the rock surfaces, are 

 Pocillopora meandrina (in the shallower regions), 

 and smaller encrusting corals and algae. Many 

 planktivorous fishes are concentrated in the water 

 column adjacent to the reef face. Understandably, 

 there is a greater variety of fishes in this habitat 

 than in the other habitats characterized here. 

 Fishes listed in Table 5 ® are characteristic of those 

 seen along the reef face during the day. 



^Table 5 is based on data from three transects at two reef-face 

 sites at Palemano Point (see Figure 1). Total number of species 

 observed on these three transects: 89; mean number of individu- 

 als of all species for a single transect: 937. 



921 



