Nonaka et al.: Seasonal variation in larval fish assemblages off eastern Brazil 



769 



r¥~r 



River Jequitinhonha 



Belmonte 



Royal Chaflotle Bank 



f 



Minerva Seamount 

 Caravelag Abroihos Reef )■' O \ 



Rodger Seamount 





Abroihos Bank 



River Paraiba do Sut - 



Cape Sao TomeJ 



River Doce 



f 



1 



Vitoria <-■ 



■: ' I 



1? 1 



Brazil Current 



ry 



"Vitbria Seamount 



^ 



/ 



cu 



Cape 

 m 



\j 100m 



<t>50m / 



U 1000m' 



Frio  SACW 200m >■ 



16°S 



17° 



18° 



19° 



■20° 



21" 



22° 



23° 



43° W 42° 



41° 



40° 



39° 



38° 



37° 



36° 



Figure 2 



Hydrographic features of the AbroUios Bank region. The dark arrow shows the main axis of the 

 Brazil Current (BC); the blank arrow the upward movement of the South Atlantic Central Water 

 (SACW), and the shadowed area the coastal upwelling (CU). 



based on descriptions in the literature (Fahay, 1983; Leis 

 and Rennis, 1983; Leis and Trnski, 1989; Moser et al., 

 1984; Moser, 1996; Nafpaktitis et al., 1977; Okiyama, 1988; 

 Olivar, 1988; Olivar and Fortuiio, 1991). Larval identifi- 

 cation of coral-reef-associated fish is difficult; therefore 

 identification was made only to the family level. The most 

 abundant Myctophidae larvae were identified to species 

 level. 



To determine the possible associations among stations, 

 the distribution pattern, and larval abundance, a multi- 

 variate analysis of numerical classification was applied 

 by using the two-way indicator species analysis (Hill et 

 al, 1975; Hill, 1979), implemented by the program TWIN- 

 SPAN. This is a divisive method that classifies stations 

 and families and produces a sorted family by station table, 

 showing the hierarchical classification in binary notation 

 (see "Appendix"). The results of this analysis show the 



clear ecological preferences of the family groups and are 

 used to identify particular environmental conditions. Only 

 the family groups with an occurrence of more than 10% in 

 each cruise were used in this analysis. 



Results 



Oceanographic conditions 



The continental shelf of the eastern coast of Brazil is gen- 

 erally narrow (ca. 25 km) and is composed of calcareous 

 sediments on the bottom; however, it widens to 230 km off- 

 shore at Caravelas (Lat. 18°S), forming the large Abroihos 

 Bank ( AB) to the south (Fig. 2). The depth of shelf break in 

 this region is 100 m with isobathic lines 200 m and 1000 m 

 very close to it. Therefore, we have shown the margin of 



