Boundaries

This ecoregion includes all of the coastal drainages along South America’s western coast between the Qubrada Seca drainage in the north to the Río Imperial drainage in southern Chile. It is limited to east by the Western Cordillera.

Topography

The ecoregion is divided into three topographic zones: the Coastal Zone, Central Depression, and Main Cordillera, with elevations that range from sea level to over 6600 m asl (Hijmans et al. 2004). It is also subdivided into major Andean divisions stretching north-south. The northernmost part of the ecoregion includes the southernmost volcanoes of the Central Volcanic Zone, including Nevado Tres Cruces (6748 m) and Nevado Ojos de Salado (6893 m), the highest active volcano summit in the world. From Copiapó to Santiago, the Coastal Cordillera meets the Pre-Cordillera and Western Cordillera. This area, called the Pampean flat-slab segment, contains no Central Depression or volcanoes due to shallow subduction of the Juan Fernández Ridge (Moreno & Gibbons 2007). From Santiago south past Concepcion is the Southern Volcanic Zone, with notable volcanoes like Maipo (5264 m), Tupungatito (5628 m), Cerro Azul (3788 m) and Llaima (3125 m). Erupting as recently as 2008 and 2009, Llaima is one of Chile’s most active volcanoes. The southern part of the ecoregion also marks the lowering of the Coastal Cordillera. Between the two cordilleras is the Central Depression, or Central Valley, which contains the richest agricultural land in the country.

Freshwater habitats

This ecoregion is home to short rivers that originate in the Andes and flow toward the Pacific Ocean. The longest, Río Biobío, originates from lakes Icalma and Galletué in the Andes and flows to the Gulf of Arauco. Río Huasco, which flows through the north-central region, has a permanent flow that is fed by snowmelt. There are also high elevation lakes, including Laguna del Laja, Laguna del Maule, the brackish Laguna del Negro Francisco and the Laguna Santa Rosa, and Laguna Verde, a salt lake. 

Terrestrial habitats

This ecoregion spans several terrestrial habitats ranging from the southern tip of the Atacama Desert and semi-arid Norte Chico in the north to matorral in Central Chile and Valdivian temperate forests in the south. Chilean matorral is the only Mediterranean shrubland in South America, and is home to many endemic plants, including keule (Gomortega keule), pitao (Pitavia punctata), ruil (Nothofagus alessandrii), and Chilean wine palm (Jubaea chilensis) (WWF 2001). The dominant vegetation types include xerophytic thorn scrub comprised of deciduous shrubs and succulents, as well as mesic communities dominated by evergreen sclerophyllous trees and forests dominated by winter-deciduous trees. This high floristic diversity reflects the geological, topographic, and climatic diversity of this mountainous coastal region (Moreno & Gibbons 2007). 

Description of endemic fishes

The endemic family Nematogenydae is represented by Nematogenys inermis, which is endangered throughout its range between the Río Maipo and Biobío basins. Perciliidae, including the endemic Percilia irwini and near-endemic P. gillissi, is near-endemic to the South Andean Pacific Slopes and Valdivian Lakes [349] ecoregions. Other endemics include the genus Bullockia (B. maldonadoi) and the species Basilichthys microlepidotus, Cheirodon galusdai, C. pisciculus, Brachygalaxias gothei, Percichthys melanops, tollo (Diplomystes chilensis), D. nahuelbutaensis, and Trichomycterus chiltoni. Trichomycterus chiltoni and Percilia irwini are restricted to the Río Biobío drainage (Dyer 2000).

Ecological phenomena

The lampreys Geotria australis and Mordacia lapicida are both anadromous and parasitic species (Dyer 2000).

Justification for delineation

This ecoregion falls within the Chilean icthyographic province of the Austral Subregion, and includes the Central area of endemism between the Río Huasco to Río Rapel and South-Central area of endemism between the Río Maule and Río Imperial (Dyer 2000).

Level of taxonomic exploration

Good