Dams in South Europe: socio-environmental approach and eDNA-metabarcoding to study dam acceptance and ecosystem health

Abstract Under current climate warming, dams and reservoirs are main options to ensure water supply in dry regions. However, the presence of these infrastructures encompasses impacts on ecosystem due alteration connectivity river habitat. We expect that as a result relation between resource population will depend their use or demand, so benefits compensate negative regions with droughts while not having same perception zones where is problem, public acceptance expected change depending area. Here, we have employed multidisciplinary approach study dam also measure health two dammed areas, Guadalhorce Nalón rivers, Mediterranean south Atlantic humid north Spain, respectively. The methodology has included Environmental DNA for phytoplankton inventory surveys stakeholders ordinary citizens dam’s acceptance. Worse bioindicators quality associated were found than Nalon River. valued more services provided by dams, especially cultural nature, those dams. Most consulted (N = 319 300 regions) favourable reservoirs. They would increase annual taxes restore connectivity, River, demolition was least supported. generally positive views help identify actions improvement rivers highlighting importance restoring without local users.