Gibbons et al : Habitat use by demersal nel<ton on the continental shelf in tie Benguela ecosystem 



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Figure 4 



Distribution of hake (Al, sole (Bi and dragonet (C) (all 

 stippled), and samples (solid) on the PCI axis which repre- 

 sented hard and soft substrata, in the sites to the south of 

 the Orange River mouth. Distribution of hake (D) and false 

 jacopever (E)(both stippled), and samples (solid) on the PCS 

 axis which represented vertical structure, in the sites to the 

 south of the Orange River mouth. The variance of all species 

 scores was significantly less than that of sample scores. 



display strong vertical migration at night and feed pri- 

 marily on macrozooplankton (Pillar and Barange, 1995), 

 a pronounced association with a benthic fauna need not 

 be expected. Should the use of the demersal environment 

 by hake during the day, therefore, simply be one of a place 

 to rest, then the preference for sandy areas needs to be 

 interpreted in terms of favored shelter. Our observations 

 of hake behavior (Fig. 7A) indicated that most individuals 

 were positioned immediately on the sand, although some 

 were buried in the upper layers of the substratum. Under 



the white lights of the Jago, these juvenile hake were pink 

 and blotchy in color and appearance and were not strongly 

 different from kingklip, and it is possible that such an ap- 

 pearance may serve to camouflage individuals. 



Cuttlefish are well known to use camouflage, and this 

 may account for the fact that they were not strongly as- 

 sociated with soft or hard substrata (Tables 4 and 6). 

 Cuttlefish are the commonest cephalopod caught in de- 

 mersal trawls (Japp, 1997), implying that they are known 

 to occur over sandy and mixed substrata. Cuttlefish feed 

 predominantly on fishes and crustaceans (Lipinski, 1992) 

 and therefore the lack of any strong association with 

 ophiuroids is to be expected. 



Grenadiers, on the other hand, tended to be associated 

 with brittlestars (Table 6). Unlike cuttlefish, however, 

 grenadiers are known to feed quite extensively on ophiu- 

 roids ^ and small epifauna (Meyer and Smale, 1991) and 

 did not seem to show any strong association with extremes 

 of substrata and were observed in both soft and hard habi- 

 tats (Table 5). The smaller species of macruorids (such as 

 C. simorhynchus) form a small but conspicuous part of the 



Adriaans,W. 2000. Unpubl.data. Zoology Department, Uni- 

 versity of the Western Cape, Private Bag X17, Bellville 7535, 

 South Africa. 



