Reproductive performance and diving behaviour share a common sea‐ice concentration optimum in Adélie penguins (Pygoscelis adeliae)

Abstract

The Southern Ocean is currently experiencing major environmental changes, including in sea-ice cover. Such changes strongly influence ecosystem structure and functioning and affect the survival and reproduction of predators such as seabirds. These effects are likely mediated by reduced availability of food resources. As such, seabirds are reliable eco-indicators of environmental conditions in the Antarctic region. Here, based on 9 years of sea-ice data, we found that the breeding success of Adélie penguins (Pygoscelis adeliae) reaches a peak at intermediate sea-ice cover (ca. 20%). We further examined the effects of sea-ice conditions on the foraging activity of penguins, measured at multiple scales from individual dives to foraging trips. Analysis of temporal organisation of dives, including fractal and bout analyses, revealed an increasingly consistent behaviour during years with extensive sea-ice cover. The relationship between several dive parameters and sea-ice cover in the foraging area appears to be quadratic. In years of low and high sea-ice cover, individuals adjusted their diving effort by generally diving deeper, more frequently and by resting at the surface between dives for shorter periods of time than in years with intermediate sea-ice cover. Our study therefore suggests that sea-ice cover is likely to affect the reproductive performance of Adélie penguins through its effects on foraging behaviour, as breeding success and most diving parameters share a common optimum. Some years, however, deviated from this general trend, suggesting that other factors (e.g. precipitation during the breeding season) might sometimes become preponderant over the sea-ice effects on breeding and foraging performance. Our study highlights the value of monitoring fitness parameters and individual behaviour concomitantly over the long-term to better characterize optimal environmental conditions and potential resilience of wildlife. Such an approach is crucial if we want to anticipate the effects of environmental change on Antarctic penguin populations.

Oceanic thermal structure mediates dive sequences in a foraging seabird

“…We observed a strong correlation between the two DFA results at each breeding stage (incubation: r = .95, p < .001; guard: r = .98, p < .001; postguard: r = .98, p < .001). Thus, both methods converged to indicate that dive sequences from foraging little penguins are best characterized as persistent, long‐range dependent fractional Gaussian noise (Figure 3), in accordance with previous studies on penguins (Cottin et al., 2014; Le Guen et al., 2018; MacIntosh et al., 2013; Meyer et al., 2015, 2017). The observed best‐scaling regions were similar for the three stages (incubation, guard and postguard) and included the scales 2 7 –2 11 , or 128–2048 s.…”

“…Previous studies have shown that dive sequences from foraging penguins are best characterized as persistent, long‐range dependent fractional Gaussian noise (Cottin et al., 2014; Le Guen et al., 2018; MacIntosh, Pelletier, Chiaradia, Kato, & Ropert‐Coudert, 2013; Meyer et al., 2017; Meyer, MacIntosh, Kato, Chiaradia, & Ropert‐Coudert, 2015). In other words, dive and postdive durations of a given length are typically followed by dive and postdive durations of a similar length, with such patterns of fluctuation between these two behavioral states persisting across a range of measurement scales.…”

Benthic ecoregionalization based on echinoid fauna of the Southern Ocean supports current proposals of Antarctic Marine Protected Areas under IPCC scenarios of climate change

“…Marine life of the SO displays unique physiological characteristics and life-history traits including high levels of endemism (Griffiths, Barnes, & Linse, 2009;Kaiser et al, 2013;Saucède, Pierrat, & David, 2014), adaptations to seasonally subzero water temperatures with high sensitivity to increase in temperature due to their narrow thermal niche (Cheng & William, 2007;Peck, 2016Peck, , 2018Portner, Peck, & Somero, 2007), and brooding (David & Mooi, 1990;Hunter & Halanych, 2008;Sewell & Hofmann, 2011), which make it particularly vulnerable to environmental changes (Guillaumot et al, 2018;Ingels et al, 2012;Lohrer, Cummings, & Thrush, 2013;Peck, 2005;Peck, Morley, & Clark, 2010;Peck, Webb, & Bailey, 2004). Multiple impacts of climate change have been documented on SO benthic marine ecosystems that are particularly endangered (Bonsell & Dunton, 2018;Constable et al, 2014;Le Guen et al, 2018;Reygondeau & Huettmann, 2014;Rogers et al, 2020;Sen Gupta et al, 2009). As highlighted previously, changes are not equivalent across the whole SO and can reach various degrees of importance depending on the region.…”

Sea-ice edge is more important than closer open water access for foraging Adélie penguins: evidence from two colonies

“…diffuse sea-ice conditions found in the MIZ (Ainley 2002, Ballard et al 2010, Barbraud et al 2015, Le Guen et al 2018. To examine their dependence on sea ice, the foraging behaviour of Adélie penguins has been studied at distant sites with contrasted sea-ice conditions (Watanuki et al 1997(Watanuki et al , 2002 or at a given colony but in years of different sea-ice conditions and/or at different breeding stages (Wienecke et al 2000, Clarke et al 2006, Nesti et al 2010, Erdmann et al 2011, Le Guen et al 2018. However, data on Adélie penguin foraging behaviour has, to date, only been obtained from a restricted number of colonies, mostly in relation to the relative ease of access of these sites to researchers.…”

“…The change in the icescape coupled with the occurrence of extreme weather events mean that the region and the resident animal populations are now facing new challenges. Populations on the Ile des Pétrels have been intensively studied over the past years, and the foraging behaviour of Adélie penguins breeding there has received considerable attention (Ropert-Coudert et al 2001a,b, 2002a,b, 2004, Cottin et al 2012, Widmann et al 2015, Le Guen et al 2018. However, the foraging response to the new icescape situation by colonies located east and west of this well-known colony remains unknown.…”