Remote Sensing-Based Assessment of Aquatic Habitat Transformation and Ecosystem Degradation Under Environmental Stress Conditions

Structural and functional changes are occurring rapidly in aquatic habitats due to increased variability in climate conditions, land use changes and pollution. This research used multi-temporal satellite data to analyze the changes in aquatic habitats and the degradation of ecosystems in a tropical river-wetland-lagoon complex that covers 1,250 km² between 2000 and 2024. Classification of images for five reference years obtained using Landsat and Sentinel-2 into seven types of land and water, along with indicators for water extent, aquatic vegetation health, water turbidity, algae, and surface water temperature, was performed. An index of environmental stress and a scale of five ecosystem degradation levels were constructed. The extent of open water decreased by 26.9%, that of aquatic and marsh vegetation by 37.1%, and that of mangrove and riparian vegetation by 26.6%; aquaculture ponds and built-up land grew more than fourfold and by 56.9%, respectively. Indicators of water turbidity and algae increased, the greenness of vegetation became worse, and surface water temperature increased by about 1.6 °C. Loss of habitat within 40 assessment units had a strong correlation with environmental stresses, and the lower wetlands and estuarine fringe were identified as the most vulnerable areas. Urbanization, aquaculture modification, and changes in water flow were recognized as the most dominant threats. The results reveal the importance of remote sensing of the environment in terms of detecting habitat degradation at an early stage.