This thesis is based on the following papers: Blanco S, Bécares E, Fernández-Aláez M 2008. Efficiency of top-down control depends on nutrient concentration in a shallow lake: a mesocosm study. Mar Freshwat Res 59: 922-930. Blanco S, Romo S, Villena MJ, 2004. Experimental study on the diet of mosquitofish (Gambusia holbrooki) under different ecological conditions in a shallow lake. Int Rev Hydrobiol 89: 250-262. Blanco S, Romo S, Villena MJ, Martínez S 2003. Fish communities and food web interactions in some shallow Mediterranean lakes. Hydrobiologia 506: 473-480 Blanco S, Romo R 2006. Ictiofauna del Lago de la Albufera de Valencia: evolución histórica y situación actual. Bol R Soc Esp Hist Nat Secc Biol 101: 45-56 Blanco S, Romo S, Fernández-Aláez M, Bécares E 2007. Response of epiphytic algae to nutrient loading and fish density in a shallow lake: a mesocosm experiment. Hydrobiologia 600: 65-76