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Fishery Bulletin 98(4) 



PQ 



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continental shelf with the 100-m isobath. 

 This region is characterized by the south- 

 ward flowing Brazil Current ( BC ), a typical 

 western boundary current regime (Castro 

 and Miranda, 1998). Because of the topo- 

 gi'aphic impediment of the Abrolhos Bank, 

 the main axis of the Brazil Current flows 

 along the outer edge of the continental 

 slope of the bank and passes through 

 the Vitoria Channel formed between the 

 southeastern edge and the Vitoria sea- 

 mount at lat. 20°15'S. It flows southwest- 

 erly from this point, approaching the coast 

 near Cape Sao Tome (Signorini et al., 1989). 

 Schmid et al. ( 1995 ) detected a permanent 

 cyclonic eddy which was formed south of 

 the Abrolhos Bank from the meandering 

 movement of the Brazil Current after pass- 

 ing through the Vitoria Channel. Beneath 

 the Brazil Current the South Atlantic Cen- 

 tral Water (SACW) occupies the subsur- 

 face layer at 120-350 m depth. Prevailing 

 northeast winds induce a coastal upwell- 

 ing in the region from Cape Frio to Cape 

 Sao Tome which is more intense during 

 the austral spring and summer, uplifting 

 the SACW to the surface (Mascarenhas et 

 al., 1971; Silva, 1973; Ikeda et al. 1974). 



The horizontal distribution of the water 

 temperature at a depth of 50 m showed 

 a flow pattern similar to that of the 

 Brazil Current on the three cruises, and 

 the thermal front of the SACW of the 

 Cape Sao Tome reached the southern rim 

 of the Abrolhos Bank (Fig. 3). The bound- 

 ary between the Brazil Current and the 

 coastal water was demarcated with a 

 24.8°C-isotherm line on the three cruises. 

 The temperature gradient between two 

 water masses on the autumn cruise was 

 more pronounced (Fig. 3C). The sea sur- 

 face temperature at 10 m depth over the 

 Abrolhos Bank ranged from 24.0-25.6°C 

 in winter, and 26.0-26.4°C in summer, to 

 26.0-28.3°C in autumn. The salinity at 

 10 m depth ranged from 36.0 to 37.5 psu 

 and showed no seasonal variation. 



Zooplankton 



The displacement volume of macrozoo- 

 plankton was low, ranging from 0.07 tol.54 

 mL/m' over the bank and from 0.01 to 0.41 

 mlVm' in the open ocean (Table 1). How- 

 ever, when compared with the displace- 

 ment volume of macrozooplankton in the 

 north Pacific central gyre, which ranged 

 from 0.05 to 0.10 mL/m-^ (Loeb, 1980), 

 our values in the open ocean were slightly 

 higher 



