Alteração nas áreas de mangue em estuários no Estado do Ceará devido a mudanças nos usos do solo e mudanças climáticas

Abstract

Mangroves vegetation covers an estimated area of about 12 to 20 million hectares worldwide. Coastal habitats such as mangroves, salt marshes and coral reefs serve as protection for the coastline from erosion and flooding. Studies assessing mangroves species threats showed that 70 species were considered endangered and could disappear in the next decade, this loss would have devastating economic and environmental consequences for coastal communities due to their importance. In the last 50 years, between 30% and 50% of mangroves have disappeared, which is still happening in some places and it is increasing at certain areas. The annual rate of disappearance of coastal ecosystems is four times greater than the rate for disappearance for rain forests. Mangroves suffer greater pressure due to the rapid conversion of forests into agricultural and urban areas, in this scenario, climate change promote specific pressures on mangroves and may increase the impacts of anthropogenic activities or from other sources. The focus of this study was to map the changes in mangrove area in twelve estuaries in Ceará between the years 1992 and 2011, and to identify the main drivers of these changes, whether they are caused by land use change within the watershed or by global climate change. There was also done a mapping rainfall trends within the Jaguaribe River watershed, this was done using data obtained from the website of the Brazilian National Water Agency (ANA) using sampling points from all the municipalities in the watershed. The results showed that 9 of the 12 estuaries showed expansions in their mangrove areas ranging from approximately 4% to 430%, the other mangroves showed a decrease from 4% to 77%. With respect to the vectors responsible for changes in areas, it was observed that the interaction between land use change and increasing sea levels allowed the mangroves to expand into new sedimentation areas, especially in rivers with dams. The mapping of rainfall trends showed that most municipalities in the watershed of Jaguaribe River suffered decrease in rainfall throughout the year and during the dry season.