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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

210: Rio Tuira

Major Habitat Type:

tropical and subtropical coastal rivers

Author:

Scott Smith, Michele Thieme

Countries:

Panama

Boundaries:

This ecoregion extends from Punta Chame in Panama (western boundary of the Río Capira) to the Río Tuira drainage in the northeast. The ecoregion also includes the Archipiélago de la Perlas in the Golfo de Panamá.

Drainages flowing into:

Golfo de Panamá and Pacific Ocean

Main rivers or other water bodies:

This ecoregion is home to some of the largest rivers of the Pacific slope, including Bayano, Tuira, Balsas, and Chucunaque. Río Tuira, one of the longest rivers, runs from its headwaters in the Sierranía del Darién to the Golfo de San Miguel. Other rivers that flow into the Golfo de San Miguel are the Sambú and Taimati. The ecoregion is also home to the artificial Lake Bayano, as well as two of the three major hydrographic watersheds of the country: Bayano-Chepo and Tuira-Chucunaque (MINSA 2007).

Topography:

Hills less than 600 m cover much of the western portion of the ecoregion, whereas mountains of the Sierranía del Darién border the northeastern edge. The Bayano and Chucunaque rivers drain in depression terrains (MINSA 2007).

Climate:

The climate of the ecoregion is humid tropical, with temperatures averaging 27 oC in the lowlands and 18 oC at higher elevations. Rainfall along the Pacific coast ranges between 1500 and 3500 mm, with the rainy season lasting from the end of April until the end of November, and the dry season between December and the end of April (MINSA 2007).

Freshwater habitats:

The freshwater habitats of this ecoregion include brackish to freshwater marshes and swamps, mangroves, rivers, and streams. Some of the larger areas of coastal mangroves and mudflats include Chame Bay, the mouths of the ríos Tapia and Pacora, the lower Río Bayano, the mouths of the ríos Juan Díaz and Tocumen, and along the coast toward Río La Maestra. Freshwater wetlands occur at Tocumen marsh, La Jagua, and the Chimán wetlands, which also includes extensive mudflats and coastal mangroves. The estuaries on the north and eastern side of the Golfo de San Miguel also contain extensive tidal mudflats and mangroves, including those around the Congo and Cucunatí, the mouth of the Río Sambú, and in the Punta Patiño Reserve (Angehr 2005).

Lake Bayano is a reservoir formed by the damming of the Río Bayano (Chepo). The lake has since become one of the most important freshwater habitats in eastern Panama.

Terrestrial Habitats:

Wet and humid lowland forest is the dominant vegetation type throughout much of the ecoregion (Stattersfield et al. 1998). The terrestrial ecoregions that comprise these moist forests include the Isthmian-Atlantic moist forests and South American Pacific mangroves that flank the Bahía de Panamá and Golfo de San Miguel, and the Chocó-Darién moist forests that border the northern and eastern side of the ecoregion. Eastern Panamanian montane forests occupy higher elevations (World Wildlife Fund 2001).

Fish Fauna:

Over 70 species of primary freshwater fishes inhabit the Tuira ecoregion. The biogeographic data presented in Smith and Bermingham (2005) combined with molecular analyses (Bermingham and Martin 1998) permit a strong inference that dispersal events resulting from river anastomosis occurring during periods of reduced sea level have had a large impact on the faunal similarity of the Santa Maria [208] and Tuira ecoregions. Thirty species are shared between the Santa Maria [208] and Tuira ecoregions. Moreover, the composition of the freshwater fish fauna of the Tuira ecoregion is similar in kind to its putative source population in northwestern Colombia. The freshwater fish communities of the Tuira ecoregion are dominated by primary freshwater fishes, mainly Characidae (20%) and the Loricariidae (18%). On the other hand, secondary freshwater fishes contribute much smaller percentage of the total richness of the fauna than they do in the northern ecoregions in lower Mesoamerica; Poeciliidae represent 13% of the fauna and Cichlidae constitute only 7% of the fauna.

Description of endemic fishes:

The Tuira ecoregion contains fourteen endemic species, including Dasyloricaria capetensis, Dasyloricaria tuyrensis, Rineloricaria altipinnis, and Sturisomatichthys citurensis (Loricariidae); Amphilophus calobrensis and Vieja tuyrensis (Cichlidae); Brycon striatulus and Bryconamericus bayano (Characidae); Apteronotus rostratus (Apteronotidae); Characidium marshi (Crenuchidae); Neoheterandria cana (Poeciliidae); Piabucina festae (Lebiasinidae); and Pimelodus punctatus (Pimelodidae).

Other noteworthy aquatic biotic elements:

The upper Bay of Panama is the most important area for aquatic birds in Panama. It is an important wintering area for migratory species, and supports large breeding colonies and resident species (Angher 2005). Lake Bayano is an important bird area, and contains one of only a few known breeding sites for Cocoi heron (Ardea cocoi) in Panama (Araúz & Gorrichátegui 2000; Angehr 2003). Ensenada de Garachiné contains small nesting colonies of great egret (A. alba) and American white ibis (Eudocimus albus) (Angehr 2005).

Six Red List amphibian species inhabit this ecoregion from five genera: Atelopus, Agalychnis, Hylomantis, Hyloscirtus,and Pipa (GAA 2006).

Justification for delineation:

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

Level of taxonomic exploration:

The level of taxonomic exploration is fair. More ichthyological work is required in the Tuira drainage basin as well as some of the southeastern drainages in Panama to fully characterize the fauna.

References/sources:

Bermingham, E.,Martin, A. P. (1998). "Comparative mtDNA phylogeography of neotropical freshwater fishes: testing shared history to infer the evolutionary landscape of lower Central America" Molecular Ecology 7(4) 499-517.

Bussing, W. A. (1976)"Geographic distribution of the San Juan ichthyofauna of Central America with remarks on its origin and ecology" In Thorson, T.B. (Ed.). Investigations of Nicaraguan lakes. (pp. 157-175) Lincoln, Nebraska: University of Nebraska.

Smith, S. A.,Bermingham, E. (2005). "The biogeography of lower Mesoamerican freshwater fishes" Journal of Biogeography 32(10) 1835-1854.

Stattersfield, A. J., Crosby, M. J., et al. (1998). "Endemic bird areas of the world: Priorities for biodiversity conservation" Cambridge, UK: BirdLife International.

World Wildlife, Fund (2001). "Terrestrial Ecoregions of the World" 2005 (2005; www.worldwildlife.org/science/ecoregions/biomes.cfm).

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