Tracking seabird migration in the tropical Indian Ocean reveals basin-scale conservation need

Résumé fourni par la source

Understanding marine predator distributions is an essential component of arresting their catastrophic declines. 1 , 2 , 3 , 4 In temperate, polar, and upwelling seas, predictable oceanographic features can aggregate migratory predators, which benefit from site-based protection. 5 , 6 , 7 , 8 In more oligotrophic tropical waters, however, it is unclear whether environmental conditions create similar multi-species hotspots. We track the non-breeding movements and habitat preferences of a tropical seabird assemblage (n = 348 individuals, 9 species, and 10 colonies in the western Indian Ocean), which supports globally important biodiversity. 9 , 10 , 11 , 12 We mapped species richness from tracked populations and then predicted the same diversity measure for all known Indian Ocean colonies. Most species had large non-breeding ranges, low or variable residency patterns, and specific habitat preferences. This in turn revealed that maximum species richness covered >3.9 million km 2 , with no focused aggregations, in stark contrast to large-scale tracking studies in all other ocean basins. 5 , 6 , 7 , 13 , 14 High species richness was captured by existing marine protected areas (MPAs) in the region; however, most occurred in the unprotected high seas beyond national jurisdictions. Seabirds experience cumulative anthropogenic impacts 13 and high mortality 15 , 16 during non-breeding. Therefore, our results suggest that seabird conservation in the tropical Indian Ocean requires an ocean-wide perspective, including high seas legislation. 17 As restoration actions improve the outlook for tropical seabirds on land 18 , 19 , 20 , 21 , 22 and environmental change reshapes the habitats that support them at sea, 15 , 16 appropriate marine conservation will be crucial for their long-term recovery and whole ecosystem restoration.

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