Assessing physical conditions of lakes

Abstract

The hydrological and morphological conditions of lakes play a fundamental role in shaping habitats for aquatic fauna and flora and are therefore key to the proper functioning of these ecosystems. Consequently, their improved consideration in water and aquatic environment management policies is essential, as required by the European Water Framework Directive since the early 2000s. To address operational gaps and enable France to meet its regulatory obligations, the ECLA R&D Unit (Research and Development Unit for Lake Ecosystems) developed several complementary methods for describing and monitoring the hydromorphological characteristics of lakes. The information collected, combined with auxiliary data from national sources, contributed to the development of the LHYMO indicator, which assesses the degree of hydromorphological alteration using fifteen metrics. The application of this indicator has, for the first time, provided a standardized nationwide assessment of the hydromorphological alteration of French lakes, regardless of their origin (natural or artificial). Furthermore, recent analyses of the impacts of these alterations on lake fauna and flora show that the metrics derived from the LHYMO indicator can explain part of the variability in the taxonomic abundance of the biological communities studied, although their influence varies among biological compartments. These findings are encouraging for improving the integration of biological responses and biodiversity considerations into lake management.