Spatial–temporal distribution of mangrove species in the estuary of the Mamanguape river in the state of Paraíba, Brazil

Abstract

Mangrove ecosystems are under pressure from various anthropic sources, such as changes in land use in watersheds and effects related to climate change. Thus, detailed monitoring of the distribution of mangrove species can provide important information concerning how such ecosystems are responding to these alterations. This study investigates the spatial–temporal distribution of mangrove species and quantifies the area of the mangrove in the Mamanguape River estuary in the state of Paraíba, Brazil. Land use and land cover changes in mangrove morest during the past 35 years (1985 to 2020) were determined using multi-temporal satellite imageries by Landsat TM and the Random Forest algorithm. The results indicated 17 classes, 9 of which belong to mangrove and 8 to associated classes. The classification of images presented overall accuracy varying between 81.9% and 92.3% and a Kappa coefficient of from 77.7% to 91.1%. We verified a trend of species distribution, in which A. schaueriana and R. mangle exhibited the greater coverage in areas under greater marine influence, while A. germinans and L. racemosa showed higher coverage in areas under greater influence of fresh water. The dominant class was composed of Rhizophora mangle, Avicennia schaueriana, and Laguncularia racemosa. Analyses into alterations of the composition of mangrove species in the estuary of the Mamanguape River indicate that the class of R. mangle, A. schaueriana, and L. racemosa and the class of A. schaueriana diminished, while the class of R. mangle and L. racemosa and the apicum class increased. There was a loss of 2.1% of the mangrove during the study period. During the year 2020 the area registered was 4,620 ha. The main causes of loss of the mangrove area were the installation of shrimp farming ponds, severe defoliation, and the conversion of mangroves into pasture. The mapping carried out in this study provides new insights into the conservation status of the mangrove forests in the Mamanguape River estuary and represents a valuable approach for informing replanting strategies and future management practices.