Boundaries

This ecoregion lies on the Pacific side of Panama. The western border is formed by the Rio Santa Maria, Rio Tabasará, and Rio San Pedro drainage basins. The Soná Peninsula acts as an effective filter barrier separating this ecoregion with Chiriqui [206]. The Santa Maria ecoregion continues eastward and encompasses the streams of the Azuero Peninsula. The ecoregion’s eastern boundary is situated between Rio Sajalices (Santa Maria ecoregion) and the Rio Capira (Tuira ecoregion [210]). The ecoregion includes Coiba Island, which lies just off the southwestern coast of Panama.

Topography

The north of this ecoregion is flanked by the Cordillera Central. Altitude varies from sea level to 1500 m above sea level, with the highest elevations and mountainous terrain concentrated along the western side (up to 2000 m) of the peninsula (Suzan et al. 2006). Further east is the volcano El Valle, which rises nearly 1200 m. Coiba Island is the largest Pacific coast island in Central America.

Freshwater habitats

The Pacific-oriented rivers of this ecoregion are longer and slower than rivers on the Caribbean side. Their basins are also more extensive. Mostly unnavigable, many originate as swift highland streams, meander in valleys, and terminate in coastal deltas (Library of Congress 1987). The rivers are characterized in general by their abundant flow volume.

The Santa Maria basin is the third largest in Panama (MINSA 2007). The once extensive fresh and brackish coastal wetlands found in the lower courses of the Rio Santa Maria and Rio Villa have since been converted to rice and sugar plantations (Angehr 2005). Near the Rio Santa Maria, Ciénaga de Las Macanas is the largest freshwater wetland remaining in the driest region of Panama (Angehr 2005).

Terrestrial habitats

The Santa Maria ecoregion historically consisted of Isthmian-Pacific moist forest throughout the western half of the ecoregion and Panamanian dry forests along the eastern edge. Today, the Azuero Peninsula is a mostly transformed agricultural landscape with low human density and scattered remnants of tropical moist and dry forests. The native vegetation consists predominantly of deciduous trees with some perennial and succulent species, grasslands, and mangrove swamps near the coast (Tosi 1971).

Mature forest covers large expanses of the central and northern part of Coiba Island with over 230 recorded species of plants, a large majority of which are trees and shrubs. The most speciose families are Leguminosae, Rubiaceae, and Melastomataceae. Higher elevation forests are dominated by Calophyllum longifolium, Eschweilera pittieri, Cassipourea elliptica, and Ternstroemia tepezapote, whereas Calophyllum longifolium, Tetragastris panamensis, and Carapa guianensis dominate the surrounding, low-lying forest. Pelliciera rhizophora and Rhizophora mangle are the most common species of the mangrove forests along the southern shore of the island, and freshwater swamps are characterized by high concentrations of Prioria copaifera and Peltogyne purpurea (Perez et al 1996).

Description of endemic fishes

There is one endemic species of primary freshwater fishes in the Santa Maria ecoregion: a characid, Bryconamericus zeteki.

Justification for delineation

Fish provinces from Bussing (1976) were revised and subdivided on the basis of application of a similarity index to sub-basin fish presence/absence data.

Level of taxonomic exploration

The level of taxonomic exploration in this area of Panama is fair. More ichthyological work is required in the drainage basins of the Azuero Peninsula. This is particularly true of the Rio Playita, Rio Pavo, Rio Oria and the Rio Cana drainage basins.