Depredación ocasional de Sus scrofa L. sobre una metapoblación relíctica de Margaritifera margaritifera L. (Bivalvia: Mollusca) en el río Negro (NO de España)

The wild boar (S. scrofa L.) is a generalist feeder that occasionally predates on semi-aquatic and terrestrial molluscs. We document for the first time the massive predation of wild boar on an aquatic epibenthic prey, the endangered freshwater mussel M. margaritifera. During the severe drought of 2009 an important part of the Negro mussel population was found predated by wild boar in a stretch subject to an episodic low level of water. Severe drought and boar predation caused the death of around 40% of the individuals in this metapopulation in the lower reaches of the river, which is the largest population near the southern limit of its global distribution. We propose a survey of the mussel colonies during periods of drought and the translocation of the mussels to deeper areas of the river in order to avoid this endangered mussel being accessible during the summer to the scavenging of wild boar.