Seabird modulations of isotopic nitrogen on islands
2012
Caut, Stéphane | Angulo, Elena | Pisanu, Benoît | Ruffino, Lise | Faulquier, Lucie | Lorvelec, Olivier | Chapuis, Jean-Louis | Pascal, Michel | Vidal, Eric | Courchamp, Frank | Estación Biológica de Doñana (EBD) ; Consejo Superior de Investigaciones Cientificas [España] = Spanish National Research Council [Spain] (CSIC) | Mécanismes adaptatifs : des organismes aux communautés ; Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS) | Department of Biology, Section of Ecology ; University of Turku | Société d'Ornithologie de Polynésie | Écologie et santé des écosystèmes (ESE) ; Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST | Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE) ; Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS) | Institut de Recherche pour le Développement (IRD) | Ecologie Systématique et Evolution (ESE) ; Université Paris-Sud - Paris 11 (UP11)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS) | ANR Aliens | ANR-05-BDIV-0003,ALIENS,Assessment and Limitation of the Impacts of Exotic species in Nationwide insular Systems(2005)
The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystems' structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents) and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in δ(15)N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers.
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