Quality and ecological restoration of aquatic systems
Urban, industrial and agricultural effluents, hydro-electric power stations, dams, irrigation, rising temperatures as a result of global warming… Human activities have both direct and indirect impacts on continental aquatic activities (waterways, lakes and estuaries) and the living organisms which they host. This phenomenon raises a dual problem: that of the ecological quality of the waterways, which is the subject of the European Water framework directive (WFD) adopted in 2000, and the problem of their capacity to provide eco-systemic "services" such as the production of resources for fishing, flow regulation, purification, etc.
Even before the launch of the WFD, through the activities of the QUASARE research topic (Quality of aquatic systems and ecological restoration) Irstea had understood and anticipated the warning signs that would force the sustainable management of water and aquatic environments to become part of national and European public policies.
Consequently, over recent years, scientific activities have led to the development of monitoring and evaluation tools and methods (bio-indicators, software to model habitat and flow management, etc.) which have enabled the public authorities to implement the first cycle of the WFD. These tools provide administrators with the means to monitor, maintain and restore aquatic environments to a good operational status.
Encouraged by these advances, scientists are now pursuing their research with a double goal: to achieve a precise understanding of hydrosystems, taking into account the temporal and operational dynamics, and to deepen the work being done on restoration by incorporating the concept of ecosystemic services. Although these shifts in emphasis are mobilizing new skills - notably partnerships in social and economic sciences, around concepts of use, perception and acceptability - and increasingly sophisticated analytical methods, such as molecular biology, they continue to be in line with the work already done. They are being conducted, as in the past, in close collaboration with the traditional institutional, academic and industrial partners of the Institute (Onema, EDF, CNR, etc.). The shared objective is to better anticipate the impact of global changes on ecological quality and the functioning of aquatic environments.
Duos of experts
From 2008 to 2015, three study and research clusters have combined the expertise of Irstea and Onema to fulfil the objectives of the European Water framework directive. The partnership for water bodies is continuing in 2016.
Three domains were identified: ecohydraulics (Toulouse), hydroecology of waterways (Lyon) and the hydroecology of
In Aix-en-Provence, the work of the scientists has led to the development of tools to evaluate the quality of the lakes, based in particular on the fish communities, chemical physics and hydromorphology. It is now focusing on new operation indicators that will enhance understanding of the vulnerability of the environments, evaluation of the success of restoration and identification of the ecological services rendered. The future of this partnership which decompartmentalizes research will depend on the interest of the French Biodiversity agency (AFB) in this mode of partnership. This agency is scheduled to be created in 2016 and will include the current functions of Onema.
Fish under high protection
For more than 30 years, Irstea scientists have been working on the conservation and restoration of diadromous fish (sturgeons, shads and eels) using scientific equipment that is unique in its field..
These resources include the experimental station of Saint-Seurin-sur-l’Isle, situated on a tributary of the Dordogne, which is one of the major research installations on diadromous fish, both in Europe and internationally. In particular, it hosts the last captive stock of European sturgeons and is working on the restoration of this species (artificial reproduction, acclimatization of the juvenile fish). On a broader level, it is studying the adaptability to global change of the early life stages of migratory fish, which are very sensitive to variations of temperature and water pollution. Its work is based to a large extent on a number of structures designed to observe and study behaviour.
To supplement the research being conducted on larval and juvenile stages, Irstea also conducts regular sampling campaigns on its research vessel L’Esturial to monitor the status of the European sturgeon population, to analyse the integration of the fish born from assisted reproduction and to estimate the survival rate of the released fish.
Lastly, the Laboratory of ichthyology of the Bordeaux Irstea centre conducts morphological, anatomical and physiological studies of the migratory fish. Its researchers are principally interested in a small bone of the inner ear, called the otolith, which has the property of preserving the chemical composition of the waters through which the fish has travelled. This innovative approach allows them to achieve a greater understanding of the migratory path of these fish using micro-chemical analysis.