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Wetlands Conservation

Wetland ecosystems are some of the most biologically diverse ecosystems on the planet, home to innumerable species of plants and wildlife. In addition to supporting a vast array of flora and fauna, wetlands perform several important ecological and geological functions—they purify and filter water sources, control flooding, stabilize shorelines, store carbon, and provide protection from natural disasters. Unfortunately, the world’s wetlands are being degraded at an alarming rate, so many international conservation efforts are now focused on preserving these delicate ecosystems and raising awareness about their issues.

Osa Conservation is leading a project to restore mangroves in the Térraba-Sierpe National Wetland, a RAMSAR site and one of the largest mangrove ecosystems on the Pacific coast of Central America. The area encompasses over 66,000 acres of land along the Térraba and Sierpe rivers, including the largest intact mangrove system in Costa Rica. This project aims not only to improve habitat for an abundance of terrestrial and marine wildlife but also to improve the livelihoods and sustainability of the local communities that live in this region.

Four decades ago, large areas of the Terraba-Sierpe National Wetlands were deforested to make room for agriculture and the mangroves cut down for timber use. Today, many of the same people who engaged in the deforestation live at a subsistence level from the wetland and recognize the value of managing this ecosystem sustainably. One such community group, APREMAA, make their living through the harvest of an edible bivalve or “piangua” that grows in the mangroves. The members of APREMAA work hand-in-hand with us to test ways to bring back the mangroves.


However, getting mangroves to grow back is not a simple task. When the forest was originally cleared, it opened way for a highly invasive fern (Acrostichum aureum) which quickly dominated the deforested areas and prevented any trees from re-establishing naturally. Removing the invasive fern and successfully replanting mangrove seedlings is difficult and highly labor-intensive. With the help of the members of APREMAA and the National University of Costa Rica, we are testing ways to control the invasive fern and restore mangrove tree species.  The results of these tests will help us find cost-effective ways to restore this extraordinary ecosystem and inform Costa Rica’s efforts to meet carbon sequestration goals to mitigate climate change.

This project has been funded by ALDI SÜD and the KfW-DEG bank and coordinated by the German consultancy bluesensus sustainability & seafood consulting. The project has been implemented by Conservation Osa, APREMAA (the Association of Piangüeros and Marine Resources of Ajuntaderas y Afines), with support from SINAC, MINAE, the National University of Costa Rica, the Costa Rican company Rainbow Export Processing and the GIZ.

For more information on the economic and natural value of the Térraba-Sierpe National Wetlands, read the following report compiled by the University of Vermont: Nature’s Value in the Térraba-Sierpe National Wetlands

Read more here about why wetlands are important in the Osa.


The launch and celebration of our mangrove restoration program in May 2018 with our collaborators and partners.