Summary of Abstract Submission

Abstract Submission No. IO50-04-0001PresentationOral


Robert JM Crawford*1, Michael J Roberts1, Matthieu le Corre2

1 Department of Environmental Affairs, South Africa
2 Laboratoire ECOMAR, Reunion, France


The role of seabirds as indicators of marine ecosystems is widely acknowledged (e.g. Piatt et al. 2007, Marine Ecology Progress Series 352, 199┐204; Parsons et al. 2008, ICES Journal of Marine Science 65, 1520┐1526). Long-term studies of seabirds at the western, eastern and southern boundaries of the South Indian Ocean suggest substantial change in ecosystems of these regions. In South Africa, eastward extensions into the Indian Ocean of breeding ranges of at least two seabirds that formerly bred only in the Atlantic Ocean, and increases in numbers breeding in the Indian Ocean of another five species that previously bred mainly on South Africa┐s Atlantic coast, followed a southeast displacement of forage resources and cooling on the Agulhas Bank. Around Madagascar some seabirds have increased but not necessarily as a result of environmental drivers. In Western Australia, there were southward shifts in breeding distributions, or rapid growth of colonies located at previous distributional limits, for a least eight tropical seabirds. By contrast, increasing SSTs reduced production and increased mortality of the temperate little penguin. At the sub-Antarctic Prince Edward Islands, recent decreases of two inshore, benthic-feeding seabirds may have resulted from southward movement of the Subantarctic Front leading to stronger through-flow, reduced sedimentation and decreased benthic production at the islands. Wide-scale monitoring of seabirds may provide insight into basin-scale changes in oceanic circulation and associated ecosystem change.