MAPPING SPATIOTEMPORAL DISTRIBUTION OF MANGROVES IN MAFIA ISLAND IN TANZANIA USING LANDSAT IMAGERY

Abstract. Mangroves are important for survival of coastal communities as they provide ecosystem services that support coastal population and their livelihoods. Most coastal communities largely depend on ecosystem services provided by mangroves such as fuel wood, building poles, charcoal, and also mangroves provide spawning ground for coastal fishes. Most importantly mangroves act as a buffer that protects coastal communities from natural hazards such as tropical storms, strong winds, beach erosion, and even tsunami. Despite the important role that mangroves play, yet mangroves are under serious threat to extinction worldwide. Many mangrove-rich developing countries, including Tanzania, are facing challenges in establishing effective management plans to protect increasingly threatened mangrove ecosystems. Most of these challenges are associated with inadequate or nonexistent of up-to-date and accurate geospatial information. Knowledge on extent and spatial distribution of mangroves is critical in planning and effective management of mangroves. The aim of this study was to assess the spatial and temporal distribution of mangroves in Mafia Island using remotely sensed data for three decades (1985–2013). Results revealed a decrease of mangroves from 3,708.36 ha in 1985 to 3,187.25 ha in 2013. From the spatiotemporal dimension point of view, the results show that overall mangroves in Mafia Island have been gradually decreasing over time. This trend suggests a decline rate of about 14 % for the period of 28 years, which is an average rate of 0.5 % per year. This rate of mangrove loss should not be underestimated; effective protection measures and sustainable utilization of mangrove resources are needed.