ecological continuity

Calling on the experience gained in deploying the Information on the continuity of ecosystems (ICE) method in continental France and in a partnership with all the overseas Environmental Directorates and Water Offices, OFB coordinated and facilitated the adaptation of the method to the tropical islands of Guadeloupe, Martinique, Mayotte and Réunion.

What happens when a river is once again free to run? In the Sélune valley (Manche department in Normandy), the largest dam-removal project in Europe is being carried out in step with an unprecedented scientific programme aiming to better understand the changes in the ecosystem, monitor the return of migratory fish and participate in the future development of the valley.

The French National River Restoration Centre, led by the French Agency for Biodiversity (AFB), organised a workshop and field visits on river continuity restoration initiatives. This was an opportunity for practitioners involved in the management of aquatic environments to discover reproducible actions targeting multiple issues, carried out in Italy, the United Kingdom, Finland and France.

In France, more than 60000 structures - dams, locks, weirs and mills - have been listed on rivers and are potential obstacles to river continuity. Important regulatory texts focus on biological continuity between major natural sites and within aquatic environments. In practical terms, these regulatory texts lead us to increase our collective efforts and actions in favour of restoring river continuity.

The notion of an aquatic continuum has become critical to understanding aquatic ecosystems in that it emphasises the need for an integrative approach, spanning both the spatial and temporal scales, to water management. Incorporating this concept in ecosystem engineering is a major challenge. In addition to mobilising integrated, multi-disciplinary scientific methods, this approach must take into account not only the fact that human uses of water are highly diverse and interconnected, but the many stakeholders as well.

The meeting, with an array of speakers, enabled researchers, elected officials, local governments, State services, developers, managers of natural areas and associations to trade thoughts on the issues, techniques and measures involved in promoting biodiversity and ecological continuity. The operational phase in network implementation has raised a number of questions.

Obstacles to flow in rivers constitute a major source of breaks in ecological continuity. Given the vast array of regulatory requirements, notably the Water framework directive, and the many environmental issues involved in restoring the ecological continuity of aquatic environments, Onema decided to create a "tool" to assess and quantify the impacts of hydraulic structures on the free movement of fish.