The aquatic beetles (Coleoptera) of the Parc Natural de s’Albufera de Mallorca, Balearic Islands

[eng] An investigation into the aquatic coleopteran fauna of the Parc Natural de s’Albufera de Mallorca in 2011-15 was compared with historical records prior to the 21st Century. Forty-nine taxa were encountered, 19 of them not previously recorded. They included several of a species cited only once before in Europe; a further 4 were confirmed or new species for the Balearic Islands. Locations were sampled in all parts of the Parc including sites for which historical data were available. The two sets of data revealed changes in species composition and abundance with losses post 20th C coinciding with deteriorated water quality. Socio-economic developments including intensive farming at the periphery, water treatment plants not keeping pace with a burgeoning human population and overabstraction of ground water during prolonged periods of drought were identified as contributing factors to increased eutrophication, salinisation and point source pollution. Radical catchment-wide measures are required to return the Albufera waters to favourable ecological condition. The study sets a repeatable baseline for monitoring ecosystem recovery.