Mangroves dwell at the land-ocean interface and are thus encroached upon by competing land-use at the coastal zone

Mangroves dwell at the land-ocean interface and are thus encroached upon by competing land use at the coastal zone. They are also subject to impacts from catchments developments. As a result, mangroves worldwide are having their extension changed (Spalding et al, 1997). Worldwide it is well accepted that mangrove extension is decreasing mostly due to conversion to other uses, in particular aquaculture, urbanization and tourism development (ITTO, 2002). In many coastal sites, however, regional environmental changes have resulted in an expansion of mangrove area. Erosion of upland soils has increased sedimentation in coastal areas of Thailand, Bangladesh, Mozambique, Venezuela and New Zealand, resulting in augmenting of mangrove area (Perez et al., 2002; Aizpuru et al., 2000; Schwarz, 2003). In other areas, global climate change may result in rising sea level with increasing saline intrusion and mangrove expansion inland. The rapid response of mangroves to regional and global environmental changes and their huge ecological importance for coastal ecology and for the millions of people dwelling along tropical coasts, makes the continuous mapping of this vegetation a fundamental tool for coastal management plans and the sustainability of coastal areas. The northeastern Brazilian coast is a semi-arid sector of the country’s littoral where watershed management has resulted in intense environmental changes. River damming and water withdraw for human use and agriculture have resulted in decreasing freshwater and sediment supply to the coastal zone. More recently, an accelerated development of tourism and shrimp aquaculture have also resulted in significant changes in the coastline. Erosion of seaward mangrove fringes, increasing saline intrusion and increasing wind driven sand transport, resulted in significant changes in mangrove cover along that part of the Brazilian coast (Lacerda & Marins, 2002; Maia & Lima, 2004). The International Society for Mangrove Ecosystems, through its Brazil Chapter (ISMEBR) together with the Institute of Marine Sciences of the Federal University of Ceará (LABOMAR/UFC) and with support form the National Research Council of Brazil (CNPq) through its Institute of the Millennium Program and the Brazilian Association of Shrimp Producers (ABCC), triggered an effort to map the overall impact of regional environmental changes on mangrove extension along the NE Brazilian coast. The present paper summarizes major findings and discusses potential impact of these changes on the environmental sustainability of the coastal zone.