Abstract
King penguins (Aptenodytes patagonicus) are an iconic Southern Ocean species, but the prey distributions that underpin their at-sea foraging tracks and diving behaviour remain unclear. We conducted simultaneous acoustic surveys off South Georgia and tracking of king penguins breeding ashore there in Austral summer 2017 to gain insight into habitat use and foraging behaviour. Acoustic surveys revealed ubiquitous deep scattering layers (DSLs; acoustically detected layers of fish and other micronekton that inhabit the mesopelagic zone) at c. 500 m and shallower ephemeral fish schools. Based on DNA extracted from penguin faecal samples, these schools were likely comprised of lanternfish (an important component of king penguin diets), icefish (Channichthyidae spp.) and painted noties (Lepidonotothen larseni). Penguins did not dive as deep as DSLs, but their prey-encounter depth-distributions, as revealed by biologging, overlapped at fine scale (10s of m) with depths of acoustically detected fish schools. We used neural networks to predict local scale (10 km) fish echo intensity and depth
distribution at penguin dive locations based on environmental correlates, and developed models of habitat use. Habitat modelling revealed that king penguins preferentially foraged at locations predicted to have shallow and dense (high acoustic energy) fish schools associated with shallow and dense DSLs. These associations could be used to predict the distribution of king penguins from other colonies at South Georgia for which no tracking data are available, and to identify areas of potential ecological significance within the South Georgia and the South Sandwich Islands marine protected area.
distribution at penguin dive locations based on environmental correlates, and developed models of habitat use. Habitat modelling revealed that king penguins preferentially foraged at locations predicted to have shallow and dense (high acoustic energy) fish schools associated with shallow and dense DSLs. These associations could be used to predict the distribution of king penguins from other colonies at South Georgia for which no tracking data are available, and to identify areas of potential ecological significance within the South Georgia and the South Sandwich Islands marine protected area.
Original language | English |
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Article number | 745200 |
Number of pages | 18 |
Journal | Frontiers in Marine Science |
Volume | 8 |
Early online date | 29 Nov 2021 |
DOIs | |
Publication status | Published - 29 Nov 2021 |
Bibliographical note
FUNDINGThe at-sea data collection and 50% of CLG’s Ph.D. studentship was provided by the Swiss Polar Institute as a grant ‘Unlocking the Secrets of the False Bottom’ to ASB. The School of Biology, University of St Andrews, funded the other 50%
of CLG’s studentship. Work at South Georgia was supported by the Natural Environment Research Council’s Collaborative Antarctic Science Scheme (CASS-129), a grant from the TransAntarctic Association grant to RBS, and a British Antarctic Survey Collaborative Gearing Scheme grant to RBS and ASB. ASB and RP were supported in part by UKRI/NERC under grant NE/R012679/1.
ACKNOWLEDGMENTS
We thank the staff at the British Antarctic Survey base at King Edward Point (South Georgia), Quark Expeditions and the crew and staff of the Ocean Endeavour and the FPV Pharos South Georgia for their help with the fieldwork logistics. We also thank the Swiss Polar Institute and the ACE foundation for funding our ACE project, and all our colleagues who assisted with acoustic
data collection at sea: Matteo Bernasconi, Inigo Everson, and Joshua Lawrence. We thank Yves Cherel for fruitful discussion on the role of prey patches for king penguins in the Kerguelen region. We also thank C. Ribout and the Centre for Biological Studies of Chizé for conducting the sexing analyses of the birds
Keywords
- acoustic surveys
- Aptenodytes patagonicu s
- diving behavior
- foraging habitat
- king penguin
- prey distribution
- Southern Ocean
- South Georgia