Freshwater fish biodiversity decline due to anthropic activities from global to local scales

Freshwater fish represent one-fourth of the world’s vertebrates and provide irreplaceable goods and services but are increasingly affected by human activities. Here I will present how anthropic disturbances changed fish biodiversity across the globe considering taxonomic, functional and phylogenetic dimensions of biodiversity. I will show that most rivers of the globe experienced drastic biodiversity changes during the two last centuries, leading to an overall increase of biodiversity but a decline in distinctiveness between rivers. I will then focus on the rivers from the Guiana shield (Northern Amazonia), one of the least impacted tropical ecosystems on earth, to show how environmental metabarcoding techniques allowed to inventory local fish and mammal faunas. Those inventories were used to link slight and scattered deforestation to local drops of biodiversity, and to regional changes in turnover in species and functions, indicating that those apparently little impacted ecosystems are currently under threat.