Monitoring Mangrove Ecosystem Change over Two Decades: A Remote Sensing and Participatory Perspective (2002–2024)

Abstract

Mangrove ecosystems are strategic areas that provide a significant number of ecosystem services to communities. However, they are becoming increasingly fragile due to natural and anthropogenic phenomena. It is therefore important to characterize mangrove ecosystems in order to implement strategies for the protection and conservation of biodiversity. The objective of this study was to contribute to a better understanding of the land use/cover dynamic and factors of change in the mangrove ecosystem of the Saloum Delta. To do this, a methodological approach combining remote sensing and surveys was used. Survey, processing and analysis of Landsat 7 and Landsat 8 satellite images were used to document the state, dynamics, and factors of change in the mangrove. The results showed a different pattern of land use/cover change between 2002 and 2024. Mangrove and urban area increased while other vegetation, tan and mudflat area decreased. Mangrove area increased by 8.81% in GMPA and 1.5% in SMPA between 2002 and 2024. The higher increase of urban area was recorded in Gandoule (23.58%) compared to Sangomar (2.07%). Other vegetation declined by 11.87% in Gandoule and 5.38% in Sangomar. Tan (-2.68%) and mudflat (-19.86%) in Gandoule lost surface area. Surveys revealed that the factors contributing to mangrove degradation were anthropogenic or natural. The primary cause of mangrove degradation is the exploitation of mangrove resources (90.1%), followed by coastal erosion (38.9%), decreased rainfall (3.8%), and salinization (3.8%). Reforestation (29.1%), prohibition of mangrove logging (22.5%), awareness-raising and monitoring with the involvement of local communities (17.9%), and prohibition of certain fishing nets (15.9%) are the main conservation policies recommended by management services and local communities. Despite these threats, mangrove ecosystems have been able to maintain an increase of mangrove.