Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard

J Fluhr (1, 2) , H Strøm (1) , Roger Pradel (2) , Olivier Duriez (2) , G. Beaugrand (3) , S. Descamps (1)

1 Norwegian Polar Institute
2 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive
3 LOG - Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187

The Arctic is experiencing environmental changes at unprecedented rates. These changes are spreading throughout the entire food web, affecting apex predators such as seabirds. Brünnich’s guillemot Uria lomvia populations in Svalbard archipelago have significantly declined since the mid-1990s. For long-lived species such as seabirds, population growth rate is highly sensitive to changes in adult survival rates, and slight changes in survival may have large consequences at the population level. Adult survival rates, were estimated for Brünnich’s guillemots individually marked and monitored from 1986 to 2011 at Bjørnøya, Svalbard. While survival appeared to be repeatedly high (mean ± SE; 95 ± 1%) from 1986 to 1995-98 (transitional years, when Svalbard guillemot colonies started to decline), it dropped by 9-12% over the period 1995-98 to 2011. This decline coincided with the occurrence of an abrupt ecosystem shift in the North Atlantic Ocean in the mid-1990s and the weakening of the Atlantic subpolar gyre. Variations in the subpolar gyre index (SGI) were significantly associated with inter-annual variation in guillemot annual survival, and a strong gyre (i.e. cold waters on guillemot wintering grounds) was associated with high adult survival. Our results, combined with other studies, suggest that the SGI may be an important global proxy to assess oceanographic conditions and changes in marine ecosystems in the North Atlantic.

Mots clés: Climate change; Adult survival; Subpolar Gyre Index; Winter North Atlantic Oscillation; Sea surface temperature; Uria lomvia; Arctic; Regime shift; Seabirds

Domaines: Biodiversité et Ecologie; Bioclimatologie

J Fluhr, H Strøm, Roger Pradel, Olivier Duriez, G. Beaugrand, et al.. Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard. Marine Ecology Progress Series, 2017, 563, pp.1-11. ⟨10.3354/meps11982⟩. ⟨hal-02104969⟩