Revista de Biología Tropical (May 2005)
Summit-to-Sea mapping and change detection using satellite imagery: tools for conservation and management of coral reefs
Abstract
Continuous summit-to-sea maps showing both land features and shallow-water coral reefs have been completed in Puerto Rico and the U.S.Virgin Islands,using circa 2000 Landsat 7 Enhanced Thematic Mapper (ETM+)Imagery.Continuous land/sea terrain was mapped by merging Digital Elevation Models (DEM)with satellite-derived bathymetry.Benthic habitat characterizations were created by unsupervised classifications of Landsat imagery clustered using field data,and produced maps with an estimated overall accuracy of >75%(Tau coefficient >0.65).These were merged with Geocover-LC (land use/land cover)data to create continuous land/ sea cover maps.Image pairs from different dates were analyzed using Principle Components Analysis (PCA)in order to detect areas of change in the marine environment over two different time intervals:2000 to 2001,and 1991 to 2003.This activity demonstrates the capabilities of Landsat imagery to produce continuous summit-to-sea maps,as well as detect certain changes in the shallow-water marine environment,providing a valuable tool for efficient coastal zone monitoring and effective management and conservation.Se elaboraron mapas de Puerto Rico y las Islas Vírgenes Estadounidenses que muestran la cobertura del suelo y el fondo en arrecifes de coral ("mapas cima-mar) con imágenes del año 2000 del Enhanced Thematic Mapper (ETM+)del satélite Landsat 7.Se fusionaron Modelos de Elevación Digital con batimetría satelital.Se caracterizaron hábitats bentónicos con clasificaciones "no supervisadas " de imágenes de Landsat,agrupando mediante datos de campo,y produciendo mapas con una precisión superior al 75%(coeficiente Tau >0.65).Estas caracterizaciones se combinaron con datos de Geocover-LC (uso /cobertura del suelo)para hacer los mapas.Comparando pares de imágenes mediante Análisis de Componentes Principales se logró identificar las zonas de cambios en los ambientes marinos en dos períodos:2000 a 2001 y 1991 a 2003.Se demostró la capacidad de las imágenes del satélite Landsat para producir mapas continuos cima-mar y para detectar cambios en los ambientes marinos someros,proveyendo así una valiosa herramienta para el monitoreo,el manejo y conservación efectiva de la zona costera.
