An Integrated Geospatial Approach to Mangrove Forest Mapping in Trinidad and Tobago Using High-Resolution Aerial Photography and Sentinel-2 Satellite Imagery

Mangrove forests provide a wide range of ecosystem services and socio-economic benefits globally; however, climatic and anthropogenic forces have negatively affected this unique vegetation type. Information on observed changes is useful in the development of mangrove conservation strategies. Geospatial mapping techniques can provide such information, which is key for the sustainable management of this critical resource. In Trinidad and Tobago, mangrove forests have suffered losses within recent years. This study utilized remote sensing and geographic information systems (GIS)techniques to update an existing 2007 mangrove baseline map of Trinidad and Tobago to 2014 and identify significant changes in mangrove coverage for the 7-year period. Mangrove forest boundaries were delineated using ArcGIS 10.4.1 software through an integrated approach involving visual interpretation of2014 high-resolution, coloured aerial photography and classification of Sentinel-2 Multi-Spectral Instrument(MSI) satellite imagery. Resultant maps were verified using ground data collected between 2017 and 2019.Spatial analysis techniques were used to isolate and quantify areas of mangrove change. Results revealed that total mangrove coverage for both islands decreased from 9369.3 ha in 2007 to 9077.2 ha in 2014, a loss of292.1 ha for the 7-year period. Solid waste pollution and land cleared for development were both observed within mangrove areas. A mangrove species map generated for the Buccoo-Bon Accord region of southwest Tobago showed that the area is dominated by red mangroves. The outputs of this study can be used in mangrove forest conservation and management strategies to promote more sustainable development practices in Trinidad and Tobago and the wider Caribbean. The geospatial approach can be implemented when developing monitoring plans.