Petits plans d’eau pour la biodiversité et conservation : contexte, conception et évaluation des mesures de restauration en Europe

Creating pond networks could enhance freshwater biodiversity and support species conservation. Pond networks have been implemented in Europe and will be promoted by recent initiatives such as the EU Nature Restoration Regulation. However, guidance is lacking on how to effectively design, monitor, evaluate and manage these systems. To address these gaps, this PhD investigated the environmental and spatial factors structuring macrophyte and macroinvertebrate communities in human-made ponds, and suitable monitoring methods. Two pond networks were studied: Neu-Woerr (France/Germany) and Silene (Latvia). Silene showed high macrophyte diversity, while Neu-Woerr had low diversity, likely due to invasive crayfish. Macrophyte and macroinvertebrate community composition was linked to variables affecting light (shade from surrounding trees and water transparency), and for macroinvertebrates also to oxygen levels. Environmental DNA metabarcoding was tested for the detection of macrophytes, macroinvertebrates, amphibians and fish, but because of technical issues only the macrophyte data was analysed. This technique still needs improvement for ponds.