Invertebrates in small shallow lakes and ponds: a new sampling method to study the influence of environmental factors on their communities
Résumé
Small shallow lakes (SSL) are reservoirs of biodiversity and provide numerous ecosystem services. Therefore, tools to easily and rapidly assess the biological integrity and conservation value of these aquatic ecosystems have been increasingly requested by environmental managers. In this study, we propose a new sampling method for monitoring aquatic invertebrates. This method, called S(3)i, allows to sample SSL with a surface area from 1 m(2) to at least 20 ha. We applied the method to 268 SSL in France and used generalised additive models to investigate factors that correlate with (1) total richness, and (2) richness and relative abundance of functional group epsilon, i.e. group of taxa exclusive of SSL richness and determining SSL functioning. Elevation, surface area, and distance from the source-a proxy of river and watershed connectivity-were identified as determinants of invertebrate richness. Invasive crayfish may directly impact total and epsilon-richness, whereas fish impact epsilon-richness and epsilon-abundances. Shoreline vegetation and vegetation cover were especially determinant for total richness, epsilon-richness, and epsilon-relative abundance. The S(3)i was successfully applied to a wide diversity of SSL in France. The sampling method can be considered as rapid, reproductible, and representative for monitoring aquatic invertebrates in SSL and should be applied to the management of a worldwide range of small shallow lakes.