A study of changing land uses in and around Toronto waterfront marshes

Land use changes associated with 45 years of urbanization within the watersheds of eight marshes east of Toronto are documented. During 1931–76 marshes were pre- empted by industrial activities, urban utilities and residential developments. It is estimated that 271 ha of marsh were reclaimed from a total of 482 ha. These encroachments have increased the isolation of marshes by severing biotic exchanges within the watershed and by reducing the continuity between the marshes. Within the waterfront marsh areas, the rate of wetland loss is accelerating. The environmental and economic implications of wetland losses are described and the urgent need for a wetland policy is pointed out.