Spatiotemporal Analysis of Mangrive Cover Change in Mida Creek, North Coast Kenya

Mangrove ecosystems provide critical ecological and socio-economic services to coastal communities, including shoreline protection, fisheries support, biodiversity conservation, and carbon sequestration. Despite their importance, mangroves along the Kenyan coast are increasingly threatened by anthropogenic pressures such as harvesting, land conversion, and habitat disturbance, as well as environmental stressors linked to climate change. Continuous monitoring of mangrove cover and condition is therefore essential for sustainable coastal management. Previous national-scale assessments using Landsat imagery have documented long-term mangrove declines along the Kenyan coastline. More recent studies in Mida Creek have applied Sentinel-2 imagery and generalized vegetation indices such as NDVI to assess mangrove condition; however, further analyses using mangrove-specific indices and multi-temporal change detection approaches remain limited. This study assessed mangrove cover change in Mida Creek, located within the Watamu Marine Protected Area ecosystem on the north coast of Kenya, between 2016 and 2025 using Sentinel-2 Level 2A imagery and open-source GIS tools. The Mangrove Vegetation Index (MVI) was applied to classify mangrove and non-mangrove cover, while post-classification comparison quantified changes in mangrove extent in terms of persistence, loss, and gain. Classification accuracy assessment indicated strong performance of the index across all years, with overall accuracy values exceeding 94% and Kappa coefficients > 0.88. Findings reveal that mangrove extent increased from 1,484.66 ha in 2016 to 1,558.34 ha in 2021 and 1,587.97 ha in 2025, representing a net gain of 103.31 ha over the nine-year period (0.77% yr⁻¹). Mangrove persistence remained high, with localized areas of loss and gain observed. While overall extent remained relatively stable, analysis of relative density categories derived from MVI values showed internal structural shifts between low, medium, and high relative density classes. Overally, the study demonstrates that freely available Sentinel-2 imagery and open-source GIS tools provide a reliable and accessible approach for monitoring mangrove dynamics and supporting coastal ecosystem management in Kenya.