Fig. 6: The socio-economic main periods in the region of Lake Redon and the context of fish introduction.

Photosynthetic pigments (green siluette) indicate fluctuations in the lake’s primary productivity, driven mainly by sheep livestock impact since 200 CE, with a high incidence during feudalism, which overlapped with the Medieval Climate Anomaly. Fish parasites (orange silluete), represented by Ichthyobodo, indicate a sustained fish occurrence since at least the 6th century. The variation in the Eurycercus lamellatus (purple silluette), the cladoceran most susceptible to fish predation, suggests that other drivers than fish impact were more relevant as drivers of the cladoceran community composition. The upper blue scale indicates the main socio-economic periods in the region. Source data can be found in Supplementary Data 1, 2, and 3.