abstract
- Droughts may be responsible for important ecological impacts in freswater ecosystems, including the death of rare species. This study assessed the mortality of the endadgered pearl mussel Margaritifera margarififera (Linnaeus, 1758) in the Mente, Rabaçal and Tuela rivers (north west of the Iberian Peninsula) during the extreme summer drought of 2017. Mortality ocuurred as a result of the low river flow, which led to mussel stranding near the banks and consumption (by predation of scavenging) by wild boar Sus scrofa (Linnaeus, 1758). Mortality differed across sites. The shell length of live mussels (measured before the drougt( and dead mussels significantly differed in the Rabaçal River, but not in the Mente and Tuela rivers. Extreme droughts are predicted to increase in number and intensity i the future, and possible impacts on rare species such as M. margaritifera populations in Iberia (and elsewhere) may now be at increased risk, and measures should be implemented in order to mitigate the impacts of future extreme droughts.