El impacto de la ganadería y la agricultura en los ecosistemas terrestres.-Las comunidades de aves como indicadoras del impacto de las transformaciones agrícolas en la cuenca vertiente al Mar Menor (Murcia, SE España)

Abstract

ABSTRACT Mediterranean coastal landscapes have suffered significant changes along the last decades due to agricultural intensification and tourism, that have altered the hydrological regime of wetlands, as has occurred in the Mar Menor (Southeast Spain). Such alterations and the consequent changes in nutrient flows are threatening the conservation of these wetlands. We analyze the effects of these ecosystemic changes on the bird assemblages, focusing on two especially sensitive communities: waterbirds and steppe passerines. Waterbirds have shown dramatic changes in their relative abundances in the lagoon, with a long-term decline in the most characteristic original species, increases in generalist piscivores and a recent appearance and rapid growth of herbivores. Among steppe passerines, the family Alaudidae has lost importance to the benefit of Turdidae and Fringillidae. These changes can be considered a loss of value in relation with the original community, since the wetland qualifies as a Specially Protected Areas under the EU’s Bird Directive, precisely on the basis of its genuine steppe bird assemblage. In conclusion, the changes at wetlands scale clearly reflect the hydrological modifications at the watershed scale and have significant effects on the most characteristic biodiversity of the wetlands of coastal arid systems