Location: The site is located in the province of Puntarenas, Osa Peninsula, about 30 km southwest of Palmar Norte.

Criteria: This book is an important habitat for many species of birds, fish, mammals and reptiles. Mangroves play a direct or indirect role in the preservation of fish. Some species depend on these sites during their life cycle or a significant part of this cycle (reproduction, growth or feeding).

Type marshes: The area includes the estuary of the Rivers Térraba and Sierpe, and adjacent lagoons (Laguna Sierpe, Laguna Porvenir), and as the periodically inundated swamp forest of mangrove palm taedigera and “yolillo” Raphia, sandy beaches and cliffs

Notes biological / ecological: The flora in the reserve is formed by hydrophilic whose growth cycle is in harmony with the aquatic environment. There are three types of vegetation (mangrove, palustrine and herbaceous) in Térraba-Sierpe. Sea life includes fish, shellfish, oysters and other shellfish. More than 55 species of fish, and there are at least 10 species that are exploited commercially. The mangrove is an area frequently visited by migratory birds such as Herons, Egrets, Cotingas, and Pandion haliaetus, there are several types of reptiles such as crocodiles, Caiman, and the Árboricoras Boas.

Hydrological / Physical notes: The Terra-Sierpe swamp is characterized by an ecosystem of marsh periodically flooded forests and mangrove forest at the mouth of Térraba and Sierpe River. The Rio Grande de Terra is the main source of freshwater into the estuarine system. Its main tributary is the Rio General, together with its tributaries. The Sierpe River forms the border of mangrove forest, has tributary rivers and streams. The mangrove vegetation plays a key role in protection from erosion and maintaining water quality, retaining the toxic pollutants in water are located near some plantations bordering the mangroves, also transfers nutrients to the soils and regulates sedimentation).

The catchment area is geologically Térraba-Sierpe ft formed in Cretaceous, Tertiary and Quaternary. The materials are of volcanic origin, erosive or alluvial origin. Most land in the site have a high amount of salt water, unstable and low oxygen levels. These lands are weak, poorly consolidated, gray or black reflecting high concentration of sulfate. The alluvial soils with good or poor drainage, resulting from sedimentation or volcanism. The site is periodically flooded by tides, which transfer organic material rich in nutrients. The total average tidal fluctuation is about 2 meters. The climate is very hot and humid, and rainfall is abundant from May to November. The average annual rainfall is 3,638 mm.

Human Uses: Térraba-Sierpe mangroves were designated as a Forest Reserve in 1977. The site is administered by the Ministry for Environment and Energy. The surrounding land is privately owned (the banana plantations, rice growing and cattle). Within the site, the mangrove products are extracted by an organized group and individual families, eg. For fuel (wood). However, the main income comes from fishing for “piangua” clam Anadara tuberculosa and crabs, and traditional fishing.