Population size and distribution of seabirds in the Cosmonaut Sea, Southern Ocean

The Cosmonaut Sea is one of the less studied ecosystems in the Southern Hemisphere. Unlike other seas which were near to coastal regions, however, few studies exist on the top predators in this zone. From December 2019 to January 2020, a survey of seabirds was carried out on the board icebreaker R/V Xuelong 2 in the Cosmonaut Sea and the Cooperation Sea. Twenty-three bird species were recorded. Antarctic petrel(Thalassoica antarctica), Antarctic prion(Pachyptila desolata), and Arctic tern(Sterna paradisaea) were the most abundant species. A total of about 37500 birds belonging to 23 species were recorded. Around 23% of the region had no record of birds. A large number of birds was recorded in 39°E–40°E, 44°E–46°E and 59°E–60°E. Many areas, such as 33°E–35°E, 39°E–41°E, 44°E–46°E and 59°E–60°E show a great richness. More than two-thirds of seabirds(71%) were observed in the zone near the ocean front. The prediction of the distributions of the most dominant species Antarctic petrel also showed that the area near the ocean front region had an important ecological significance for seabirds. The results suggest that the distribution of seabirds in the Cosmonaut Sea is highly heterogenous.