External and local controls on land-sea coupling assessed by stable isotopic signatures of mangrove producers in estuaries of Pacific Panama

Abstract Foliar stable isotopic signaturesof nitrogen, carbon, and sulfur in mangrovevegetation from the Pacific coast of Panama were insensitive to inputs from watersheds with different area of forest land cover, and to seasonal, inter-annual, and global-scale-driven contrasts in rainfall and upwelling. N, C, and S content of mangrovevegetation were not affected by inputs from watersheds with different degrees of deforestation, but showed some influence of down- estuarytransformations. While there was substantial variation that remained un-explained, isotopic signaturesand nutrient contents were largely determined by species-specific features, and showed substantial small-scale variation reflecting local differences, within- estuaryplant-sediment links. The ability of mangrove estuariesto erase effects of deforestationpoints out that conservation of these wetland ecosystems is important, because, at least in the sites we studied, transformations within mangrove estuarieswere strong enough to protect water quality in receiving coastal waters.