Boundaries

This ecoregion includes the coastal drainage basins between the Rio Araranguá and Rio Tramandaí systems along with the associated coastal lagoons. This area encompasses the extreme northern portion of the coastal plains of Rio Grande do Sul and southern Santa Catarina states of Brazil.

Topography

The Tramandaí-Mampituba ecoregion extends across sandy plains and dunes along the coast to undulating rolling plains further inland. Along the western border elevations rise to more than 1000 m asl up the steep and rugged escarpment of the Serra Geral, which is noted for its massive canyons (Hijmans et al. 2004). This range is the southern portion of the Serra do Mar, and separates the narrow coastal plain from the Paraná Plateau. The ecoregion comprises Paleozoic and Mezozoic sedimentary and volcanic rocks in the highlands, as well as more recent sedimentary deposits along the shoreline (Noble 1967; Tomazelli et al. 2000). 

Freshwater habitats

The ecoregion includes short rivers and streams that flow from the highlands to lagoons or the Atlantic Ocean. Rio Araranguá rises in the Serra Geral, flowing through canyons and falls before reaching the coast. Rio Maquiné flows into the Lagoa dos Quadros. Flat coastal plains are marked by lagoonal systems separated from the ocean by sand barriers (Carosu et al. 2000). The entire lower portion of the lagunar system is dominated by interconnected freshwater marshes (Banhados) that remain flooded during the winter rainy season. The mid and upper reaches of the rivers draining into the plains are characterized by boulder and coble deposits that form most of the channel structure.

Terrestrial habitats

Three terrestrial ecoregions occur within the Tramandaí-Mampituba freshwater ecoregion: Atlantic coast restingas, Serra do Mar coastal forests, and Araucaria moist forests (WWF 2001). The Atlantic coast restingas line the coast of this ecoregion south from the mouth of the Rio Araranguá.  These pioneer Atlantic forests are rich in species of Myrtaceae, Leguminosae, Euphorbiaceae, and Malphigiaceae. Marsh grasslands are also found along the coastline around estuarine areas and beaches. Further inland are Atlantic moist forests with species of Leguminosae, Sapotaceae, and Lauraceae that dominate the emergent and canopy layers, as well as mosses, lichens, and epiphytes. Araucaria moist forests start around 400-500 m and occur at higher elevations. They are a mixture of different types of Atlantic moist forest with an emergent layer of Brazilian Araucaria (Araucaria angustifolia) (Noble 1967; WWF 2001).

Description of endemic fishes

The one endemic genus is represented by a single species, Odontostoechus lethostigmus, which is located in the Maquiné, Três Forquilhas, and Mampituba River basins. Two-thirds of the 15 endemic species, however, are in the loricariid and atherinopsid families. These include multiple species of Odontesthes, Rineloricaria, Epactionotus, and Pareiorhaphis. Other endemics include the cichlid Gymnogeophagus lacustris, the callichthyid Scleromystax salmacis, and anablepid Jenynsia sanctaecatarinae.

Other noteworthy fishes

Three species occur in marine, brackish, and fresh waters: the Argentinian silverside (Odontesthes bonariensis), Atlantic sabretooth anchovy (Lycengraulis grossidens), and violet goby (Gobioides broussonnetii). The Atlantic sabretooth anchovy is anadromous, migrating into freshwater to spawn. The violet goby, in contrast, is amphidromous, moving between marine and freshwater during its life cycle.

Ecological phenomena

Extensive migrations of mullets and ariid catfishes occur in estuaries that serve as nursery areas for juveniles.

Justification for delineation

The Tramandaí-Mampituba ecoregion falls within Gery’s (1969) East Brazilian faunal region and southeastern province and Ringuelet’s (1975) ríos costeros S.E. Brasil ichthyographic province. This ecoregion contains lower endemism than the Southern Mata Atlântica [331], although there is one endemic genus.

Level of taxonomic exploration

Good