Isotopic Investigations of Seabirds of the North Water Polynya: Contrasting Trophic Relationships Between the Eastern and Western Sectors

• Published in: The Condor
• Main Authors: Hobson, Keith A., Gilchrist, Grant, Falk, Knud
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2002
• Subjects: Arctic; Canada; Coburg Island; Ellesmere Island; Greenland; Alle alle; Arctic cod; Black guillemot; Black-legged Kittiwake; Boreogadus saida; Cepphus grylle; Coburg island; Dovekie; Glaucous Gull; Groenlandia; Larus hyperboreus; rissa tridactyla; thick-billed murre; Uria lomvia; uria
• Online Access: http://dx.doi.org/10.1093/condor/104.1.1; http://academic.oup.com/condor/article-pdf/104/1/1/29710979/condor0001.pdf

Abstract We used δ15N and δ13C analyses of blood, muscle, and liver tissues to evaluate similarity of diet among five seabird species: Black Guillemot (Cepphus grylle), Black-legged Kittiwake (Rissa tridactyla), Dovekie (Alle alle), Glaucous Gull (Larus hyperboreus), and Thick-billed Murre (Uria lomvia) nesting at Coburg Island on the west and Hakluyt Island on the east side of the North Water Polynya between Ellesmere Island, Canada, and northwest Greenland. We hypothesized that dietary differences should occur because the two neighboring sites are subject to different oceanographic conditions, one result of which is differential timing of spring open water. Relative trophic level, derived from tissue δ15N values, ranged from 3.6 for Dovekie from Hakluyt Island to 4.7 for late-breeding-season diets of Thick-billed Murre adults from Coburg Island. At Coburg Island, trophic level of hatching year (HY) kittiwakes, murres, and Glaucous Gulls was higher than that for adults. This pattern was not found at Hakluyt Island, where chicks of all species generally occupied lower trophic positions. These findings suggest that lower-trophic-level prey were more important to Hakluyt Island seabirds, possibly due to lower availability of arctic cod (Boreogadus saida). Investigaciones Isotópicas de Aves Marinas en el Canal Aguas del Norte: Contrastando las Relaciones Tróficas entre los Sectores Este y Oeste Resumen. Usamos análisis de δ15N y δ13C en tejidos sanguineos, musculares y hepáticos para evaluar la similitud en la dieta entre cinco especies de aves marinas (Cepphus grylle, Rissa tridactyla, Alle alle, Larus hyperboreus y Uria lomvia). Estas especies anidan en la Isla Coburg en el lado oeste y en la Isla Hakluyt en el lado este del Canal de las Aguas del Norte, que se presenta libre de hielos y está situado entre la Isla Ellesmere en Canadá y el noroeste de Groenlandia. Hipotetizamos que las diferencias en la dieta se deberían a que los dos sitios vecinos están sujetos a diferentes condiciones oceanográficas, resultando ...