The aim of our project is to describe the bacterial community diversity of two Basque estuaries:, Bilbao estuary, a metropolitan and industrial zone, which is surrounded by this large city (~1 million habitants), while the other one, Urdaibai estuary, is a UNESCO biosphere reserve located in a relatively pristine environment. On the one hand, Bilbao estuary was previously (70s-80s) considered one of the most polluted estuaries in Europe, however, a new water sewage treatment (since late 90s) and the considerable reduction of the industrial activity in the area have significantly decreased the pollution. Indeed, the system is showing signs of recovery after decades of extremely reduced biodiversity according to studies on zooplankton, benthic community, macroalgae, and fish. On the other hand, the nearby estuary of Urdaibai (< 50 km) is located at one of the most pristine areas of the North of Spain and is considered a biodiversity hotspot. Although both estuaries have been studied in detail regarding their water quality and eukaryotic organisms, the study of the bacterial communities has been traditionally neglected.
