Diatom Scales

The Llobregat River (Chapter 6, Section 1, Figure 7) is a 165 km long river placed in a 4,948 km 2 wide catchment with mixed substrate (Sabater et al., 2012) . It is a greatly modified catchment (Becker 2014) located in a partially agricultural setting. Many changes were made through the addition of hydroelectric power plants and 3 dams. The first dam , La Baells,   is in the main river axis and two in the Cardener tributary (Marcé et al. 2012) . It is one of the most populated basins of the Catalan river system, since more than 3 million people occupy it. Most of the demographic density is at the lower course. There, agricultural and industrial pressures affect the river quality to a high degree. This Basin suffers both anthropological and natural pressures. Some of the headwater streams, such as Saldes and Gavarresa, have a naturally high salt concentration created by halite substrate. It can have up to 20 times the marine salt concentration depending on flow (Badia Guitart