Abstract

BLANCO-LIBREROS, Juan F. Global changes in Gulf of Urabá mangroves (Colombia): between the changing coastline and the expanding agricultural frontier. Actu Biol [online]. 2016, vol.38, n.104, pp.53-70. ISSN 0304-3584.  https://doi.org/10.17533/udea.acbi.v38n104a06.

Accelerated mean sea level rise and deforestation are two global changes severely impacting mangroves along the Colombian Caribbean coast, but little has been discussed about them for the Gulf of Urabá. The objective of this review is to synthesize the published literature on such topics available to date for this area. This gulf holds extensive areas, structurally different from the rest of the Caribbean, which are shrinking and degrading as a consequence of: a) coastal erosion and sea level rise; b) selective logging and agricultural expansion; and c) watershed deforestation and sediment exports to the estuaries. The Atrato River delta, and several microdeltas located along the eastern coast have expanded, while the Rionegro Cove has remained relatively unchanged, at least during the 20^th century. The eastern coast, with the smalles mangrove patches, have eroded at a rate of various meters per year due to the littoral drift currents. In the vicinity of the Turbo municipality, selective logging for different purposes has reduced the mean tree-diameter in Rhizophora mangle and has increased the importance value of Laguncularia racemosa, thus altering above ground biomass and carbon reservoirs. Agricultural expansion has been responsible for shrinking inland Avicennia germinans-stands. High deforestation rates in the coastal plains and watersheds in the banana agricultural district have increased river sediment load that has accumulated in the deltas. Mangroves in these areas trap significant amounts of sediments, with likely negative effects on colonization and survival of seedlings and benthic macroinvertebrates. In conclusion, in the Gulf of Urabá significant global changes, both natural and anthropogenic, currently occur within the littoral zone as well as within the coastal watersheds, and they require an urgent implementation of adaptive measures within the management plans for mangrove ecosystems and the coastal zone.

Keywords : coastal erosion; deforestation; forest-agriculture transition; mangroves; sedimentation.

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