Boundaries

The region includes all of the Atlantic versant rivers of Honduras between the Chamelecón-Ulúa drainages in the west, including the large Río Coco on the Honduras-Nicaragua border, and Kukalaya-Wawa drainages around Puerto Cabezas, Nicaragua.

Topography

The topography of the ecoregion is generally mountainous, except for the narrow coastal plain and valleys of the Ulúa and Aguán rivers, the Mosquito Coast in eastern Honduras, and the coastal plain in northeastern Nicaragua. Some of the ranges in the ecoregion include the Cordillera Nombre de Dios, Sierra La Esperànza, and Cordillera Isabelia. Elevations range from sea level to over 2700 m in the interior highlands. Here, the substrate primarily comprises Paleozoic metamorphic and sedimentary rocks and sediments, granitic formations, and ultramaphic rocks (Villar Anleu 1994).

Freshwater habitats

The ecoregion contains a handful of Ramsar sites, including Parque Nacional Jeanette Kawas, Refugio de Vida Silvestre Punta Izopo, and Barras de Cuero y Salado, which is a complex of estuarine and riverine wetlands  comprised of flooded forest and a network of rivers and channels. Laguna de Bacalar, located further east, is a coastal-brackish saline lagoon (Wetlands International 2002).

Terrestrial habitats

This ecoregion contains a range of habitat types from moist forests, pine forests, and mangroves along the coast to pine-oak forests, montane forests, and dry forests in the interior highlands. The lowlands are dominated by moist broad-leaf species. In contrast, the Miskito pine forests, which extend from the Mosquito Coast to northeastern Nicaragua, are dominated by Caribbean pine (Pinus carribaea). This area of pine forest represents the largest remaining lowland tropical pine-savanna in the Neotropics. Dominant species within the pine-oak forests include Pinus spp., Quercus spp., Ostrya sp. and Alnus spp. Interspersed within the moist and pine-oak forests are pockets of dry and montane forests (World Wildlife Fund 2001).

Description of endemic fishes

Compared to surrounding ecoregions, endemism within the ecoregion is low. The two species include the smoothbelly goby, Sicydium gymnogaster, and the cichlid, Theraps wesseli. At least one undescribed poeciliid, Poecilia sp., from the upper Ulúa and Aguán drainages may also be endemic.

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.