Author:

Keywords:

mangrove forest, carbon dynamics, import, export, biogeochemistry, burial, neosarmatium-smithi crustacea, stable-isotope composition, vascular plant-tissues, receiving waste-water, forest gazi bay, leaf-litter, early diagenesis, fiddler-crabs, french-guiana, rhizophora-mangle, Science & Technology, Life Sciences & Biomedicine, Plant Sciences, Marine & Freshwater Biology, NEOSARMATIUM-SMITHI CRUSTACEA, STABLE-ISOTOPE COMPOSITION, FOREST GAZI BAY, LEAF-LITTER, EARLY DIAGENESIS, FIDDLER-CRABS, RHIZOPHORA-MANGLE, ASIAN MANGROVE, FATTY-ACIDS, SEDIMENT ACCUMULATION, 0502 Environmental Science and Management, 0602 Ecology, 0607 Plant Biology, Marine Biology & Hydrobiology, 3103 Ecology, 3108 Plant biology, 4102 Ecological applications

Abstract:

Our current knowledge on production, composition, transport, pathways and transform nations of organic carbon in tropical mangrove environments is reviewed and discussed. Organic carbon entering mangrove foodwebs is either produced autochthonously or imported by tides and/or rivers. Mangrove litter and benthic microalgae tire Usually the most important autochthonous carbon sources. Depending on local conditions, phytoplankton and seagrass detritus imported with tides may represent a significant supplementary carbon input. Litter handling by the fauna not only affects microbial carbon transformations, but also the amount of organic carbon available for export. Most mangrove detritus that enters the sediment is degraded by microorganisms. Aerobic respiration and anaerobic sulfate reduction are usually considered the most important microbial respiration processes, but recent evidence suggests that iron respiration may be important in mangrove sediments as well. Organic carbon that escapes microbial degradation is stored in sediments and in some mangrove ecosystems, organic-rich sediments may extend to several meters depth. Many mangrove forests also lose a significant fraction of their net primary production to coastal waters. Large differences occur between mangrove forests with respect to litter production and export. Mangrove-derived DOC is also released into the water column and can add to the total organic carbon export. Numerous compounds have been characterized from mangrove tissues, including carbohydrates, amino acids, lignin-derived phenols, tannins, fatty acids, triterpenoids and n-alkanes. Many of these may, together with stable isotopes, exhibit a strong source signature and are potentially useful tracers of mangrove-derived organic matter. Our knowledge on mangrove carbon dynamics has improved considerably in recent years, but there are still significant gaps and shortcomings. These are emphasized and relevant research directions are Suggested. (C) 2007 Elsevier B.V. All rights reserved.