Capítulo 7. Las aves acuáticas del Mar Menorrespuesta al cambio ambiental a distintasescalas

Résumé

Wetlands are essential areas for human development due to the multiple ecosystem services they provide, and as ecosystems with a high degree of biodiversity they are home to many species of high ecological and conservation value. However, they are also among the most threatened ecosystems on the planet, and in the case of coastal wetlands this is mainly due to their natural fragility as receptors and transitional systems, as well as to the human exploitation of their resources down the ages. With various specific objectives in mind, this chapter presents a number of studies on the response and bio-marker role of waterbirds to certain functional processes and structural gradients characteristic of the Mar Menor coastal lagoon and its associated terrestrial ecosystems (especially those derived from agricultural intensification and urban development), on different spatial and temporal scales. Datasets recorded through different sampling methodologies are analyzed according to the scale of the study and its predefined objectives. Studies cover both the overall response of the community and the indicator role of focal species or guilds with regard to the chosen factors and gradients. One of the most significant results of these studies shows how the community of waterbirds is usually trivialized when the trophic conditions of the system change, reducing its global conservation value. This process is observed on different spatial scales and occurs sequentially through identifiable phases with well-defined environmental characteristics. The response of species to local processes (such as eutrophication) is mediated by more general preferences regarding the immediate landscape structure, tolerance to man, feeding strategies and trophic requirements. These findings highlight the important role played by natural shoreline habitats and the first band of shallow water in ensuring the richness, diversity and abundance of waterbirds. The studies have extended our knowledge of the effects of certain human factors and landscape features on the biodiversity of the lagoon, helping to develop more efficient assessment and management models. Thus, there appears to be a need to standardize and couple biological monitoring programs (e.g. that of waterbirds) with land management schemes on different scales. This approach should result in the development of integrated management plans that will make it possible to harmonize the aims of biodiversity conservation (e.g. Birds and Habitats Directives) with those of water quality achievement (Water Framework Directive and Marine Strategy Framework Directive).