Retreating Shorelines as an Emerging Threat to Adélie Penguins on Inexpressible Island

Xintong Chen,Xiao Cheng,Xianglan Li,Jiquan Chen,Lizhong Zhu,Bing Li

doi:10.3390/rs13224718

Abstract

Long-term observation of penguin abundance and distribution may warn of changes in the Antarctic marine ecosystem and provide support for penguin conservation. We conducted an unmanned aerial vehicle (UAV) survey of the Adélie penguin (Pygoscelis adeliae) colony on Inexpressible Island and obtained aerial images with a resolution of 0.07 m in 2018. We estimated penguin abundance and identified the spatial extent of the penguin colony. A total of 24,497 breeding pairs were found on Inexpressible Island within a colony area of 57,507 m2. Based on historical images, the colony area expanded by 30,613 m2 and abundance increased by 4063 pairs between 1983 and 2012. Between 2012 and 2018 penguin abundance further increased by 3314 pairs, although the colony area decreased by 1903 m2. In general, Adélie penguins bred on Inexpressible Island at an elevation <20 m, and >55% of penguins had territories within 150 m of the shoreline. This suggests that penguins prefer to breed in areas with a low elevation and close to the shoreline. We observed a retreat of the shoreline on Inexpressible Island between 1983 and 2018, especially along the northern coast, which may have played a key role in the expansion of the penguin colony on the northern coast. In sum, it appears that retreating shorelines reshaped penguin distribution on the island and may be an emerging risk factor for penguins. These results highlight the importance of remote sensing techniques for monitoring changes in the Antarctic marine ecosystem and providing reliable data for Antarctic penguin conservation.

Highlights

The Adélie penguin (Pygoscelis adeliae) is a circumpolar seabird that breeds on ice-free areas around Antarctica, usually close to open sea or polynya [1]
There is minimal human activity on Inexpressible Island, suggesting that t guin colony is predominately affected by the environment and landscape settin first records of Adélie penguin abundance on Inexpressible Island were obtained fo when 17,120 breeding pairs were identified; this figure increased to 21,183 breedin when 17,120 breeding pairs were identified; this figure increased to 21,183 breeding pairs in 2012 breeding season [19]
We found a rapid retreating of the shorelines from 1983 to 2018 (Table 2, Figure 2)

Summary

Introduction

The Adélie penguin (Pygoscelis adeliae) is a circumpolar seabird that breeds on ice-free areas around Antarctica, usually close to open sea or polynya [1]. This species is very sensitive to physical changes in climate and landscape, and has been considered an ecoindicator of the Southern Ocean marine ecosystem [2]. Due largely to the rapid changes in the environment under the warming climate, penguin population dynamics in Antarctica have become a major focus in both scientific investigations and conservation [3,4,5].

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Results

Discussion

Conclusion