After a dive, a Eurasian Otter (Lutra lutra) shakes itself to maintain its fur, which is essential for insulation and survival in an aquatic environment.
Discreet and elusive, the Eurasian otter is a valuable bioindicator: its presence is a sign of a healthy river.
As a top predator at the apex of the food chain, it must consume around 10 to 15% of its body weight each day, roughly one kilogram of food (fish, crustaceans, amphibians). Such abundance is only possible in rich aquatic environments, where good water quality allows microorganisms and insects at the base of the food web to thrive.
Furthermore, the otter is extremely sensitive to bioaccumulation: chemical pollutants such as heavy metals and pesticides concentrate along the food chain until they reach it. Its active presence and successful reproduction therefore provide a particularly reliable biological indicator, revealing an aquatic ecosystem that is functional and well preserved.
