1 Kenya Marine and Fisheries Research Institute, P.O. Box 837, Naivasha, Kenya. E-mail: ptobade@yahoo.co.uk
2 Biodiversity Platform Belgium, c/o Institute for Nature Conservation, Kliniekstraat 25, B-1070, Brussels, Belgium
3 Laboratory of Forest Management and Spatial Information Techniques, University of Gent, Coupure 653 Gent, B9000 Gent, Belgium

Anthropogenically induced changes in a Kenyan mangrove ecosystem assessed by application of remote sensing and Geographical Information Systems: a case study in Gazi.

Interactions between the coastal environment and the people who use its resources are poorly understood. In developing countries, many of these people are poor. Gazi Bay (Kenya) is a good example of a mangrove area which has undergone changes mainly attributed to anthropogenic activities with many of the inhabitants being categorised as poor.

This study shows the assessment of the mangrove ecosystem of Gazi Bay, with the use of remote sensing and Geographic Information Systems (GIS) techniques. It aims to analyse impacts of environmental variations and anthropogenic disturbances on landscape structure. Remote sensing data available indicate change in vegetation structure between 1965 and 1992.
Environmental data and tree characteristics data were collected from six selected sites: three were chosen from areas where changes in vegetation structure occurred; and three from areas that remained unchanged. The choice was based on observations made from change-detection map of Gazi Bay (1965-1992) (De Cauwer, 1996). Information from past scientific studies was integrated into GIS using ArcView software, creating thematic maps.

Some parts of Gazi area are subject to heavy exploitation of the mangroves due human activities. Documented information on past studies indicates a bias in sampling locations being found towards the western and northwestern areas.