title: Small birds, big effects: the little auk (Alle alle) transforms high Arctic ecosystems.
abstract: In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk (Alle alle), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios (δ15N andδ13C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical-chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevatedδ15N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algalδ15N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland.
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Vejlsøvej, 25, 8600 Silkeborg, Denmark ivg@fcien.edu.uy.|Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Iguá 4225, Malvín Norte, 11400 Montevideo, Uruguay.|Laboratorio de Etología, Ecología y Evolución, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
authors.forename: Ivan
authors.identifier: 0000-0001-7727-362X
authors.initials: I
authors.lastname: González-Bergonzoni
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Kasper L
authors.initials: KL
authors.lastname: Johansen
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Mosbech
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Vejlsøvej, 25, 8600 Silkeborg, Denmark.
authors.forename: Frank
authors.initials: F
authors.lastname: Landkildehus
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Vejlsøvej, 25, 8600 Silkeborg, Denmark.|Sino-Danish Centre for Education and Research, University of Chinese Academy of Sciences (UCAS), Room N501, UCAS Teaching Building, Zhongguancun Campus, Zhongguancun South 1st Alley, Haidian District, Beijing 100190, People's Republic of China.|Greenland Climate Research Centre (GCRC), Greenland Institute of Natural Resources, Kivioq 2, 3900 Nuuk, Greenland.
authors.forename: Erik
authors.initials: E
authors.lastname: Jeppesen
authors.affiliation: Department of Bioscience and Arctic Research Centre, Aarhus University, Vejlsøvej, 25, 8600 Silkeborg, Denmark thd@bios.au.dk.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Davidson
mesh_terms: D000818:Animals; D001110:Arctic Regions; D046091:Charadriiformes; D017753:Ecosystem; D020387:Food Chain; D006116:Greenland
keywords: arctic food webs; ecosystem engineer; marine-derived nutrients; nutrient subsidies; seabird colonies; stable isotopes