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Habitat or biological connectivity is critical for maintaining species movements, flow of resources and ecological functioning across landscapes. In aquatic systems, connectivity equates to the maintenance of water flow and connection between different ‘patches’ of water, and as such water or aquatic connectivity is vital for aquatic species to exist and move within the aquatic landscape. In wetland systems, dis-connectivity can occur for a number of reasons including via natural processes, such as seasonal hydrological changes that result in a disconnection between water bodies during dry periods, but also as a result of human-induced changes including water extraction and diversion, invasive plant growth and installation of dams and other water control infrastructure.

The lifecycle of many fish includes a migratory cycle in which they move throughout several types of water bodies. As fish migrate upstream they encounter natural (e.g. a waterfall) or man-made (e.g. a dam, weir, or culvert) obstructions, which can slow or stop the migration process. Fish passes are designed to help fish overcome these obstacles; they become key elements for reproductive success for fish returning to their spawning grounds.

Xe Champhone wetland is located in Champhone District, Savannakhet Province in central Lao PDR. It is a complex wetland system composed of a diversity of habitat types including the Xe Champhone River, open floodplain wetlands, flood forest, oxbow lakes and a number of reservoirs and modified water bodies. The wetland system has a natural seasonal flooding and drying regime that reflects the extremes of the monsoonal climate and the distinct rainfall differences between the wet and dry seasons.

The combined influence of invasive species impacts, infrastructure and other modifications at Xe Champhone wetland have resulted in overall reduced connectivity of wetland habitat impacting species movements, water flows and maintenance of ecological processes. This study aims to identify sites where significant ‘disconnection’ has occurred and re-opening management is required to improve wetland connectivity and habitat integrity. ‘Re-opening’ is defined as the action of re-instating or improving natural flow patterns. A range of activities to implement re-opening may be needed including invasive species management, removal of obstructions (infrastructure/dikes etc.) or improving species movements around obstacles, such as by installing fish ladders.

This study will identify and map priority sites for re-opening, identify causes and extent of disconnection at each site, outline management actions, feasibility and technical approaches to re-opening, as well as propose a work plan for on-ground implementation and recommendations for long-term sustainability of maintaining connectivity at these sites.