Past, Present and Future of Sri Lankan Coastal Macrophyte-Dominated Ecosystems: Blue Carbon, Conservation, Restoration and Policy

Mangroves, salt marshes and seagrasses are conspicuous and important features of the Sri Lankan coastline, playing an important role in delivering multiple ecosystem services including carbon sequestration (the so-called blue carbon ecosystems). Together, they support coastal biodiversity, provide habitat and nutrition for numerous plant and animal species, protect vulnerable coastlines and support millions of human beings. Sri Lanka is now placing itself at the forefront of marine conservation by becoming the first nation to legislatively protect all its remaining mangrove forests. The current area of mangrove forest in Sri Lanka (19,500 ha) is less than that of salt marsh (33,573 ha) and seagrass meadows (23,819 ha). There is, however, considerable uncertainty in these estimates, particularly in some regions, which hampers policy development and conservation goals. While knowledge of the value of ecosystem services provided by mangrove forests is improving (e.g. value to fisheries, national estimates of carbon stocks and sequestration rates), comparable studies on saltmarsh and seagrass ecosystems are rare and this is reflected in their governance and legal protection. Further, while there are considerable efforts to restore lost mangrove forests (i.e. more than 1200 ha restored, with ambitious plans for 10,000 ha), restoration of seagrasses and salt marshes remains largely unattempted. The current disparity in the state of knowledge of blue carbon ecosystems must be addressed through application of robust science that extends descriptive data and theoretical assumptions to generate deeper knowledge on the structure, function and socio-economic value of each of these important ecosystems. Overall, this review seeks to summarise the state of these important higher-plant-dominated coastal ecosystems in Sri Lanka. We seek to help set a research agenda to ensure the nation becomes a regional leader with respect the protection, conservation and restoration of its coastal zone, thereby ensuring continued delivery of important ecosystem services, especially blue carbon sequestration.