Boundaries

This ecoregion includes the drainage basin of the Rio Ribeira de Iguapê and coastal drainages of the state of São Paulo. It extends as far north as the coast around the Baia de Sepetiba in the state of Rio de Janeiro.

Topography

This narrow coastal ecoregion extends from the Serra do Mar escarpment to the Atlantic Coast. The Serra do Mar, which includes the ranges Serra da Bocaina and Serra do Paranapiacaba, is a fault scarp consisting of Precambrian crystalline rocks of the Brazilian Shield (Dillenburg & Hesp 2009). The relief is dramatic, with rugged mountains and steep slopes, and elevations that exceed 1800 m asl.  Sedimentary plateaus and marine deposits occur along the littoral or coastal plain, which is broader in the south around mouth of the Ribeira de Iguapê (WWF 2001).

Freshwater habitats

Fluvial discharges are limited in this ecoregion since most of the major rivers draining the Serra do Mar drain toward the interior of the continent (Dillenburg & Hesp 2009). The Rio Ribeira de Iguapê, however, is an Atlantic river that cuts a deep ravine in its short course from its headwaters in the Serra Paranapiacaba to the Atlantic Ocean. Its lower basin flows into the estuarine lagoon complex of Iguape-Cananéira-Paranaguá, which has extensive tidal rivers, flood plains, beaches, mangroves, and sandy barrier habitats (Diegues 1995). Another estuary is the Santos-São Vicente estuarine system, which comprises three major channels – São Vicente, Santos, and Bertioga. It is highly modified, but contains extensive areas of mangrove forests (Diegues 1994).

Terrestrial habitats

Atlantic moist forests are the dominant vegetation type in this region and range from shrubs and lowland forests to montane forests. The remaining large tracts of montane forest and diversity of Bromeliaceae, Myrtaceae, Melastomataceae, Lauraceae, and Orchidaceae species, in particular, make the forests of Serra do Mar distinct from other Atlantic moist forests (WWF 2001). 

Description of endemic fishes

There are 36 endemic species, and another 20 that are restricted to only two ecoregions. There are no endemic genera, however. One-third of the catfish are endemic, such as Microcambeva ribeirae, which is restricted to clear streams. Nearly 18% of Characiformes are endemic, 48% of Cyprinodontiformes, and 57% of Perciformes, including the cichlids Crenicichla iguapina, Crenicichla jaguarensi, Australoheros ribeirae, and Geophagus iporangensis.

Justification for delineation

This ecoregion falls within Ringulet’s (1975) coastal rivers of Southeastern Brazil ichthyographic province.

Level of taxonomic exploration

Good