The north coast of Rio de Janeiro (Southeastern Brazil) (Fig. 1) is
naturally depleted of rock or other hard substrates, and is covered by
extensive sandy beaches with variable amounts of mud and
calcareous nodules (i.e., rhodolites; Zalmon et al., 2002). This area is
located in a transitional zone between warm and oligotrophic waters
of the Brazil Current from the north and cold, nutrient-rich upwelling
of the South Atlantic Central Water from the south (Valentin and
Monteiro-Ribas, 1993). Primary productivity (chlorophyll a) is low,
Secchi depth does not exceed 4 m, and strong bottom currents are
common (Krohling and Zalmon, 2008). Although dominated by
oligotrophic waters and homogeneous bottom relief, the north coast
of Rio de Janeiro is often exploited by local inshore artisanal fishermen
(Zalmon et al., 2002)