Coastal and marine ecological changes and fish cage culture development in Phu Quoc, Vietnam (2001 to 2011)

Abstract

This study employed image enhancement for LANDSAT TM and ALOS imagery to monitor the changing status of coastal resources from 2001 to 2011, object-based classification of high-resolution THEOS imagery to extract fish cage culture sites and interpolation methods to determine marine environmental quality in 2011 in the northern part of Phu Quoc Island. There were five classes in the study site: natural forest, Melaleuca forest, agriculture, peat and built-up areas. Agricultural land and Melaleuca forest changing into built-up areas constituted approximately 51.13% of the total area changing. The benthic seagrass habitat increased dramatically from 2001 to the end of 2010. Besides, marine culture has been concerned to cage culture which is one of the sources directly affecting aquatic life and water quality in coastal environment. Cage culture locations were detected using high-resolution imagery as THEOS data for image fusion and Object-based Image Analysis methods. Water quality criteria including nitrogen, phosphorus and chlorophyll-a concentrations were determined by interpolation method, and the spatial distribution of these parameters showed a concentration in the study area in the range from 0.17 to 0.49 mg/L, 0.012 to 0.073 mg/L and 0.26 to 1.046 μg/L, respectively.

Keywords:

• remote sensing
• GIS
• coastal zone
• change detection
• marine environment
• seagrass
• cage culture
• water quality

Acknowledgements

We thank the Vietnamese Government and Asia Institute Technology for the scholarship and financial support. The authors thank Dr Theo Ebbers from the Wetlands Alliance Program (WAP) for providing additional research funding. Many thanks are due to Cantho University, College of The Environment and Natural Resources, Department of Applied Hydrobiology, College of Aquaculture and Fisheries for laboratory and equipment supports and Kien Giang Environmental Science and Technology Department and Phu Quoc Economic Division for the provision of secondary data and field surveys.