Journal Article Chinstrap penguin foraging area associated with a seamount in Bransfield Strait, Antarctica

9 ( 4 )  , pp.393 - 400 , 2015-12
Identifying marine features that support high foraging performance of predators is useful to determine areas of ecological importance. This study aimed to identify marine features that are important for foraging of chinstrap penguins (Pygoscelis antarcticus), an abundant upper-trophic level predator in the Antarctic Peninsula region. We investigated the foraging locations of penguins breeding on King George Island using GPS-depth loggers. Tracking data from 18 birds (4232 dives), 11 birds (2095 dives), and 19 birds (3947 dives) were obtained in 2007, 2010, and 2015, respectively. In all three years, penguins frequently visited an area near a seamount (Orca Seamount) in Bransfield Strait. The percentage of dives (27.8% in 2007, 36.1% in 2010, and 19.1% in 2015) and depth wiggles (27.1% in 2007, 37.2% in 2010, and 22.3% in 2015) performed in this area was higher than that expected from the size of the area and distance from the colony (8.4% for 2007, 14.7% for 2010, and 6.3% for 2015). Stomach content analysis showed that the penguins fed mainly on Antarctic krill. These results suggest that the seamount provided a favorable foraging area for breeding chinstrap penguins, with high availability of Antarctic krill, possibly related to local upwelling.
高次捕食者の採餌の集中する海洋環境要因を調べることで、その海域の生態系のホットスポットを特定することができる。本研究では、南極半島域の代表的な高次捕食者、ヒゲペンギンにGPS-深度ロガーを繁殖期3シーズンにわたって取り付け、採餌にとって重要な海域を調べた。ヒゲペンギンは各年とも、繁殖地から25 km離れたブランスフィールド海峡の中にある直径約10 kmの海山をよく訪れていた。この海山周辺の海域では、海域の面積と繁殖地からの距離によって予測される数を上回る潜水が観測され、ペンギンはそこでナンキョクオキアミを捕食していた。この海山周辺では表層の海流と海底地形の作用による局地的な湧昇が生じ、それがナンキョクオキアミの利用可能性を高めることで、ヒゲペンギンの好適な餌場が形成されていたと考えられる。

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