Abstract
Simple SummaryStable isotope analysis (SIA) and Stable isotope analysis in R (SIAR) model were used to identify the diet composition and regional differences of Adélie and Emperor penguins in Ross Sea region. Adélie Penguin at Cape Hallett fed on Antarctic krill and Adélie Penguin at Inexpressible Island fed on ice krill and Antarctic silverfish. Emperor Penguins fed on Antarctic silverfish regardless breeding site. Therefore, Adélie Penguin showed regional difference in the diet and Emperor Penguin showed no regional differences in the diet. These diet composition of penguins is affected by competition and distribution of prey, it is important to study the diet of penguins in relation to the sympathetic food sources needed to understand the changes in energy flows and Ross Sea ecosystems due to climate change.To identify the dietary composition and characteristics of both Adélie (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) penguins at four breeding sites, we performed stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of down samples taken from penguin chicks. Adélie Penguin chicks at Cape Hallett mostly fed on Antarctic krill (Euphausia superba; 65.5 ± 3.5%), a reflection of the prevalence of that species near Cape Hallett, and no significant differences were noted between 2017 and 2018. However, Adélie Penguin chicks at Inexpressible Island, located near Terra Nova Bay, fed on both Antarctic silverfish (Pleuragramma antarctica; 42.5%) and ice krill (Euphausia crystallorophias; 47%), reflecting the high biomass observed in Terra Nova Bay. Meanwhile, no significant difference was noted between the two breeding sites of the Emperor Penguin. Emperor Penguin chicks predominantly fed on Antarctic silverfish (74.5 ± 2.1%) at both breeding sites (Cape Washington and Coulman Island), suggesting that diet preference represents the main factor influencing Emperor Penguin foraging. In contrast, the diet of the Adélie Penguin reflects presumed regional differences in prey prevalence, as inferred from available survey data.
Highlights
Extreme environments such as Antarctica are sensitive to climate change, and sea-ice dynamics and temperature fluctuations affect organisms in the Antarctic environment [1,2]
The diets of Adélie Penguin chicks at Cape Hallett exhibited a high proportion of Antarctic krill at 65.5 ± 3.5% and no significant difference was noted in yearly comparisons
The diets of Adélie Penguin chicks on Inexpressible Island exhibited a high proportion of Antarctic silverfish compared with those at Cape Hallett (Table 2), and a significant difference was noted for Adélie Penguins depending on whether they were from Cape Hallett or Inexpressible Island
Summary
Extreme environments such as Antarctica are sensitive to climate change, and sea-ice dynamics and temperature fluctuations affect organisms in the Antarctic environment [1,2]. Climate change affects the ecology of predators that feed on plankton, krill, and fish, representing an important part of the Antarctic food web that is highly related to the sea ice habitat [3,4,5,6]. The Ross Sea, which is a large marine protected area (MPA) in Antarctica, has been recognized for its ecological importance as a breeding site of the Adélie Penguin, Emperor Penguin, and Antarctic silverfish. It hosts breeding sites (e.g., Cape Crozier, with approximately 153,000 breeding pairs [7]) for over 100,000 pairs of Adélie Penguins (Pygoscelis adeliae), and more than 20% of the worldwide population of Emperor Penguins (Aptenodytes forsteri) exist in the Ross Sea region. Penguin feeding activity is strongly affected by changes in prey availability, so it is important to study penguin diets to understand Ross Sea food web dynamics
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