Coupling of mangroves to the productivity of estuarine and coastal waters

Abstract

Most of the tropical coastline between 25° N and 25° S latitude is vegetated by forested wetlands called mangroves (McGill, 1958). These plant communities have received considerable botanical investigation because of their unique taxonomy and ovivipary (Tomlinson, 1986), and the diverse fauna that inhabit these coastal areas (Macnae, 1968;Chapman, 1976). However, the ecology of mangroves is poorly understood, particularly the significance of these ecosystems to the productivity and nutrient cycling of estuarine and adjacent coastal waters. It has been suggested that the high fishery yields of coastal tropical waters are due to the presence of these communities (Macnae, 1974; Turner, 1977; Jothy, 1984), yet there is no evidence of a cause and effect relationship for mangroves and fisheries (Macnae, 1974). Thus the function of these wetlands in supporting secondary productivity continues to be a complex issue. Mangroves may also influence the primary productivity of coastal waters by controlling the fate of dissolved nutrients and suspended sediments. Mangroves are considered a source of organic detritus yet a nutrient sink, contributing to the confusion of their role in coastal processes.