Molecular dietary analysis of Adélie (Pygoscelis adeliae) and Gentoo (Pygoscelis papua) penguins breeding sympatrically on Antarctic Ardley Island using fecal DNA

Penguin-Driven Dissemination and High Enrichment of Antibiotic Resistance Genes in Lake Sediments across Antarctica

Numerous penguins can propagate pathogens with antibiotic resistance genes (ARGs) into Antarctica. However, the effects of penguin dissemination on the lake ARGs still have received little attention via guano deposition. Here, we have profiled ARGs in ornithogenic sediments subject to penguin guano (OLS) and nonornithogenic sediments (NOLS) from 16 lakes across Antarctica. A total of 191 ARGs were detected in all sediment samples, with a much higher abundance and diversity in OLS than in NOLS. Surprisingly, highly diverse and abundant ARGs were found in the OLS with a detection frequency of >40% and an absolute abundance of (2.34 × 109)-(4.98 × 109) copies g-1, comparable to those in coastal estuarine sediments and pig farms. The strong correlations of identified resistance genes with penguin guano input amount, environmental factors, mobile genetic elements, and bacterial community, in conjunction with network and redundancy analyses, all indicated that penguins were responsible for the dissemination and high enrichment of ARGs in lake sediments via the guano deposition, which might greatly outweigh local human-activity effects. Our results revealed that ARGs could be carried into lakes across the Antarctica through penguin migration, food chains, and guano deposition, which were closely connected with the widespread pollution of ARGs at the global scale.

Are the diets of sympatric Pygoscelid penguins more similar than previously thought?

In recent years, functional changes in Southern Ocean are becoming more noticeable, due to climate change and increasing human impacts, including a growing fishery that is concentrating in the Antarctic Peninsula (AP) region. Antarctic krill Euphausia superba is often the primary prey species for animals such as Pygoscelis penguins, a sentinel species for ecosystem monitoring and management. During the last two decades in the AP gentoo penguin numbers (Pygoscelis papua) have increased and their range has shifted southward, in contrast to the decline in numbers of Adélie (P. adeliae) and chinstrap (P. antarcticus) penguins. Given divergent population trends, the goal of this study was to examine differences in their diet, and size structure of Antarctic krill recovered from penguin diet samples. The study is based on diet samples collected during the austral summers on King George Island (South Shetland Islands) where P. adeliae, P. antarcticus, and P. papua breed in mixed colonies. Results indicate that the penguins consumed krill of similar sizes during the breeding period. In contrast to prior diet studies, we found higher proportions of krill in the gentoo diet and changes in the percentage of krill in the diet relative obtained during 1970s. The similarity in diets among all three species suggests that the availability prey items (e. g., fishes) may be changing and driving higher dietary overlap. Moreover, we also check differences in krill length among penguin individuals and we did not find any statistically significant differences. We also found plastic debris in penguin stomachs during both summers.