the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Seasonal foraging behavior of Weddell seals relation to oceanographic environmental conditions in the Ross Sea, Antarctica
Abstract. Understanding the foraging behavior of marine animals is crucial for assessing their ecological significance and responses to environmental changes. In the context of Antarctica, marine animals face rapid and profound environmental changes related with global warming. However, our understanding of their responses remains limited owing to the formidable challenges inherent in conducting observations, particularly during the harsh austral winter months. In this study, we investigated the influence of changes in seawater properties and light conditions on the seasonal foraging behavior of Weddell seals (Leptonychotes weddellii) in the Ross Sea, Antarctica. We affixed 35 Weddell seals with CTD tags to record their locations and dive profiles, including depth, head acceleration, temperature, and salinity. We found that seals foraged more frequently in modified shelf water and ice shelf water compared to Antarctic surface water. This preference could be connected to greater food availability. Additionally, seals also dove to greater depths and displayed increased activity in capturing prey during daylight hours. This behavior may correspond to the diel vertical migration of pelagic prey in response to varying light conditions. Our findings suggest that Weddell seals have adjusted their foraging behaviors to adapt to spatial and temporal changes in oceanographic conditions. This highlights the importance of extrinsic factors in estimating their seasonal foraging behavior.
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RC1: 'Comment on egusphere-2023-2757', Fabien Roquet, 24 Apr 2024
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This manuscript describes the foraging behaviour of Weddell seals in the Ross Sea, using oceanographic and behavioural data logged using miniaturized loggers attached to the seals. While no ground-breaking result is obtained in this study, the data is of value and the analysis deserves its own publication conditional to major revisions.
I have in particular one major concern about the quality control of data. The authors cite in many places the publication of Yoon and Lee 2021. This publication is written in Korean in what appears to be a corean journal. This does not follow international standards and I am unable to follow what is written there. I believe the authors should treat this publication as a technical report, and assume the reader is unable to utilize it. For this reason, the current work should provide more extensive information about the different corrections that have been estimated and applied (Step 1 to Step 3 in section 2.2). The authors do not seem to be aware of the work of Siegelman et al 2019 either, which provides several recommandations for quality-control including density removal and thermal cell effect corrections.
The analysis of water masses appears very rough. Figure 3 is very hard to read, and it has some strange features such as the MSW being “stuck” at 300m for most of the period. It would be nice to show some profiles and/or sections to get a better sense of what you are trying to show. One wonder also how much of your results depend on the different spatial sampling between the two years. I suggest the authors refine their analysis of hydrographic data to produce more specific results.
Figure 6 is amongst the less informative I have every seen. That the mixed layer is deeper in winter than in summer shouldn’t come as a surprise for anyone even remotely interested in oceanography. This cannot reflect the main novelty of this work. The authors need to clarify what is the main novelty of this study.
Minor comment:
l. 35: this sentence seems to imply you are talking about “climate” change, because that’s what you are describing earlier on, and maybe also because you use the word “adapt”. Yet, the changes you describe in the text are related to diurnal/seasonal variability only. The abstract needs to be clarified.
l. 109-110: this accuracy numbers seem overly optimistic. See Siegelman et al. 2019 for recent estimates of accuracies.Citation: https://doi.org/10.5194/egusphere-2023-2757-RC1
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