Abstract
Simple SummaryThe diet of Adélie penguins, Pygoscelis adeliae, in the Ross Sea was studied applying quantitative polymerase chain reaction (qPCR) protocols to their feces. Two krill species (Euphausia superba and Euphausia crystallorophias) and notothenioid fish (mainly Pleuragramma antarctica and Pagothenia borchgrevinki) were among the most abundant components of the diet. The composition of the two krill species and notothenioid fish was found to be strongly related to the geographic characteristics of the Ross Sea.The diet of Adélie penguins, Pygoscelis adeliae, is a useful indicator in understanding the ecological conditions of their habitats. The diets of Adélie penguins were studied using metabarcoding and quantitative PCR (qPCR) analyses of fecal DNA from seven habitats along the Ross Sea region. Using metabarcoding analysis with dual universal primers (18Sv9 and miniFish), the overall diet composition and detailed information about piscine prey were clearly elucidated. It was found that two krill species (Euphausia superba and Euphausia crystallorophias) and notothenioid fish were the most abundant in the diets of Adélie penguins. Among the notothenioid prey, Pleuragramma antarctica (56.50%) and Pagothenia borchgrevinki (18.21%) were the two most abundant species. qPCR analysis showed a significant geographic difference in the composition of main prey. Penguins inhabiting outbound parts of the Ross Sea (Capes Adare (CA) and Duke of York Island (DY)) mainly preyed on E. superba, without any significant changes in prey composition. By contrast, those inhabiting the inbound parts of the Ross Sea (Edmonson Point (EP) and Inexpressible Island (II)) preyed on E. crystallorophias and notothenioid fish rather than E. superba. Compared with the outbound habitats, prey compositions for penguins inhabiting the inbound regions were significantly different year to year, which was presumably due to the food availability based on the annual environmental and meteorological conditions of the coastal region along with the inbound parts of the Ross Sea.
Highlights
The Adélie penguin, Pygoscelis adeliae, is known to be the most abundant and widely spread penguin species in Antarctica, distributed along the entire coast of the continent [1]
We investigated the diets of Adélie penguins from seven habitats along the Ross Sea, Antarctica, by metabarcoding analysis of isolated fecal DNA, which was collected for three years (2017 to 2019)
Fresh scat samples from individual Adélie penguins were collected from their breeding colonies in the Ross Sea Region Marine Protected Area, including Cape Adare (CA), Duke of York Island (DY), Cape Hallett (CH), Cape Wheatstone (CW), Mandible Cirque (MC), Edmonson Point (EP), and Inexpressible Island (II) (Figure 1 and Table 1)
Summary
The Adélie penguin, Pygoscelis adeliae, is known to be the most abundant and widely spread penguin species in Antarctica, distributed along the entire coast of the continent [1]. Penguin diets have been identified by the morphological classification of ingesta collected by a stomach flushing technique according to standard methods of the CCAMLR Ecosystem Monitoring Program (CEMP) (CCAMLR, 2014) These traditional methods have several limitations for long-term or frequent surveys, mainly because of the high cost and labor, limited accessibility to target species, the occasional adverse environmental impact on the site during sample collection, or administrative approval [11,12]. Metabarcoding analysis of fecal DNA can be applied when it is difficult to access a predator’s stomach contents [6,15] Such studies depend solely on a single marker, a short 18S region, which makes it challenging to know the exact species name or precise quantitative value of each prey item
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