The NADW flows between depths of 1,500 and 3,000 m. It is a cold water mass
(3 to 4 °C) with salinities ranging from 34.6 to 35 %. It flows southwards up to 32°S,
but part flows back northwards at higher latitudes (Silveira et al. 2000). The CUW
may be considered as part of the BC at the Brazil-Malvinas Confluence, although the
exact definition of the BC at this latitude is controversial (Gordon 1988).
In summary, the BC shows different features along the Brazilian coast. It is
shallow, warm and salty at low latitudes (from 10 to 20°S) because it is composed
basically by the TW. The SACW is incorporated into the BC at 20°S and ascends
at 28 to about 750 m. Actually, from 25°S southwards, the BC is well-consolidated
and is composed by the TW, the SACW, the AIW and the NADW, forming a
water column 3 km in depth (Silveira et al. 2000).
Along the southeast continental shelf, from 22 to 23°S, a seasonal upwelling
phenomenon, the Cabo Frio Upwelling System, occurs. This provides nutrient
enrichment onshore (Franchito et al. 1998; Mahiques et al. 2005; Sumida et al.
2005). This upwelling is ecologically important because the surface layers of water
on the coast are formed by the CW and the TW with low levels of productivity
(Franchito et al. 1998; Silveira et al. 2000). Some geographic features of the
coastline and continental shelf favor upwelling in the Cabo Frio region. The orientation of the shoreline changes abruptly from N–S to E–W and the continental
shelf narrows (Valentin 1984; Franchito et al. 1998). When strong northeast winds
prevail for several days, usually from September to March during spring-summer,
the surface water mass is moved offshore and is replaced onshore by the cold and
enriched SACW. When cold fronts reach this region from June to August in the
winter, the S-SW surface winds blow for a few days and the upwelling cycle is
interrupted. Therefore, the seasonality of the upwelling at Cabo Frio area is
associated with the movements of the SACW from offshore to onshore and vice
versa (Valentin 1984; Franchito et al. 1998).
9.2 Echinoderm Research
9.2.1 Historical Remarks of Echinoderm Research in Brazil
Studies on echinoderms in Brazil have always been characterized by a general
approach in which they are considered only as part of the benthic fauna in a given
area. The history of such studies can be traced back to 1648 when Marcgrave (1942)
reported the first echinoderm species of the Brazilian coast. In his ‘‘Brazilian
Natural History’’ the echinoderms were included in the fourth book, which registered the fishes, crustaceans and zoophytes. As zoophytes he listed two sea stars,
probably Luidia senegalensis (Lamarck, 1816) and Oreaster reticulatus (Linnaeus,
1758), a brittle star, probably of the genus Gorgonocephalus Leach, 1815, and two
sand dollars, both probably Mellita quinquiesperforata (Leske, 1778).
304
C. R. R. Ventura et al.
(3 to 4 °C) with salinities ranging from 34.6 to 35 %. It flows southwards up to 32°S,
but part flows back northwards at higher latitudes (Silveira et al. 2000). The CUW
may be considered as part of the BC at the Brazil-Malvinas Confluence, although the
exact definition of the BC at this latitude is controversial (Gordon 1988).
In summary, the BC shows different features along the Brazilian coast. It is
shallow, warm and salty at low latitudes (from 10 to 20°S) because it is composed
basically by the TW. The SACW is incorporated into the BC at 20°S and ascends
at 28 to about 750 m. Actually, from 25°S southwards, the BC is well-consolidated
and is composed by the TW, the SACW, the AIW and the NADW, forming a
water column 3 km in depth (Silveira et al. 2000).
Along the southeast continental shelf, from 22 to 23°S, a seasonal upwelling
phenomenon, the Cabo Frio Upwelling System, occurs. This provides nutrient
enrichment onshore (Franchito et al. 1998; Mahiques et al. 2005; Sumida et al.
2005). This upwelling is ecologically important because the surface layers of water
on the coast are formed by the CW and the TW with low levels of productivity
(Franchito et al. 1998; Silveira et al. 2000). Some geographic features of the
coastline and continental shelf favor upwelling in the Cabo Frio region. The orientation of the shoreline changes abruptly from N–S to E–W and the continental
shelf narrows (Valentin 1984; Franchito et al. 1998). When strong northeast winds
prevail for several days, usually from September to March during spring-summer,
the surface water mass is moved offshore and is replaced onshore by the cold and
enriched SACW. When cold fronts reach this region from June to August in the
winter, the S-SW surface winds blow for a few days and the upwelling cycle is
interrupted. Therefore, the seasonality of the upwelling at Cabo Frio area is
associated with the movements of the SACW from offshore to onshore and vice
versa (Valentin 1984; Franchito et al. 1998).
9.2 Echinoderm Research
9.2.1 Historical Remarks of Echinoderm Research in Brazil
Studies on echinoderms in Brazil have always been characterized by a general
approach in which they are considered only as part of the benthic fauna in a given
area. The history of such studies can be traced back to 1648 when Marcgrave (1942)
reported the first echinoderm species of the Brazilian coast. In his ‘‘Brazilian
Natural History’’ the echinoderms were included in the fourth book, which registered the fishes, crustaceans and zoophytes. As zoophytes he listed two sea stars,
probably Luidia senegalensis (Lamarck, 1816) and Oreaster reticulatus (Linnaeus,
1758), a brittle star, probably of the genus Gorgonocephalus Leach, 1815, and two
sand dollars, both probably Mellita quinquiesperforata (Leske, 1778).
304
C. R. R. Ventura et al.