Potential energy gain by whales outside of the Antarctic: prey preferences and consumption rates of migrating humpback whales (Megaptera novaeangliae)

Owen, Kylie; Kavanagh, Ailbhe S.; Warren, Joseph D.; Noad, Michael J.; Donnelly, David; Goldizen, Anne W.; Dunlop, Rebecca A.

doi:10.1007/s00300-016-1951-9

Cited by 42 publications

(43 citation statements)

References 85 publications

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“…This growth rate is close to the average growth rate (range 0.1-0.6 d −1 ) of Southern Ocean isolates cultured in a range of light and Fe conditions mimicking in situ conditions throughout the year [98], as well as phytoplankton growth rates measured in situ [99]. Similarly, Southern Hemisphere rorquals (Balaenopteridae) feed predominantly, although not exclusively, in the Southern Ocean summer on Antarctic krill and fast during the winter at lower latitudes [100,101]. Thus, in our model, the consumption of krill by whales is not the summer consumption rate (d −1 ) multiplied by 365 days, but instead is scaled properly to represent the annual consumption rate.…”

Section: (D) Caveats and Limitationssupporting

confidence: 76%

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems

Maldonado

Surma

Pakhomov

2016

Phil. Trans. R. Soc. A.

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This study aimed to create the first model of biological iron (Fe) cycling in the Southern Ocean food web. Two biomass mass-balanced Ecopath models were built to represent pre- and post-whaling ecosystem states (1900 and 2008). Functional group biomasses (tonnes wet weight km) were converted to biogenic Fe pools (kg Fe km) using published Fe content ranges. In both models, biogenic Fe pools and consumption in the pelagic Southern Ocean were highest for plankton and small nektonic groups. The production of plankton biomass, particularly unicellular groups, accounted for the highest annual Fe demand. Microzooplankton contributed most to biological Fe recycling, followed by carnivorous zooplankton and krill. Biological Fe recycling matched previous estimates, and, under most conditions, could entirely meet the Fe demand of bacterioplankton and phytoplankton. Iron recycling by large baleen whales was reduced 10-fold by whaling between 1900 and 2008. However, even under the 1900 scenario, the contribution of whales to biological Fe recycling was negligible compared with that of planktonic consumers. These models are a first step in examining oceanic-scale biological Fe cycling, highlighting gaps in our present knowledge and key questions for future research on the role of marine food webs in the cycling of trace elements in the sea.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

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Section: (D) Caveats and Limitationssupporting

confidence: 76%

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems

Maldonado

Surma

Pakhomov

2016

Phil. Trans. R. Soc. A.

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“…Hence, successful migration and reproduction are assumed to depend on the presence of a high biomass of Antarctic krill. However, departures from the classical feeding paradigm, indicated by feeding along the migration routes 4 – 7 and diversified biochemical feeding signals 8 , 9 have been observed in several southern hemisphere humpback whale breeding populations in recent years, putting the validity of the paradigm under scrutiny.…”

Section: Introductionmentioning

confidence: 99%

Interannual variability in the lipid and fatty acid profiles of east Australia-migrating humpback whales (Megaptera novaeangliae) across a 10-year timeline

Groß

Virtue

Nichols

et al. 2020

Sci Rep

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Southern hemisphere humpback whales are classified as high-fidelity Antarctic krill consumers and as such are vulnerable to variability and long-term changes in krill biomass. Evidence of heterogeneous feeding patterns of east coast of Australia migrating humpback whales has been observed, warranting a comprehensive assessment of interannual variability in their diet. We examined the lipid and fatty acid profiles of individuals of the east coast of Australia migrating stock sampled between 2008 and 2018. The use of live-sampled blubber biopsies showed that fatty acid profiles varied significantly among all years. The two trophic indicator fatty acids for Antarctic krill, 20:5ω3 and 22:6ω3 remained largely unchanged across the 10-year period, suggesting that Antarctic krill is the principal prey item. A distance-based linear model showed that 33% of the total variation in fatty acid profiles was explained by environmental variables and climate indices. Most of the variation was explained by the Southern Annular Mode (23.7%). The high degree of variability observed in this study was unexpected for a species that is thought to feed primarily on one prey item. We propose that the observed variability likely arises from changes in the diet of Antarctic krill rather than changes in the whale’s diet.

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“…In recent years, departures from the classical feeding model have been observed in several SHHW populations, with feeding along their migration routes reported in breeding populations from Western Africa, East Australia, and both Pacific and Atlantic sides of South America [ 8 , 23 – 29 ]. A rise in such observations may simply be an artefact of the rapid, post-whaling re-expansion of the Southern Ocean baleen whale stocks [ 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

Isotopic Evidence of a Wide Spectrum of Feeding Strategies in Southern Hemisphere Humpback Whale Baleen Records

et al. 2016

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Our current understanding of Southern hemisphere humpback whale (Megaptera novaeangliae) ecology assumes high-fidelity feeding on Antarctic krill in Antarctic waters during summer, followed by fasting during their annual migration to and from equatorial breeding grounds. An increase in the number of reported departures from this feeding/fasting model suggests that the current model may be oversimplified or, alternatively, undergoing contemporary change. Information about the feeding and fasting cycles of the two Australian breeding populations of humpback whales were obtained through stable isotope analysis of baleen plates from stranded adult individuals. Comparison of isotope profiles showed that individuals from the West Australian breeding population strongly adhered to the classical feeding model. By contrast, East Australian population individuals demonstrated greater heterogeneity in their feeding. On a spectrum from exclusive Antarctic feeding to exclusive feeding in temperate waters, three different strategies were assigned and discussed: classical feeders, supplemental feeders, and temperate zone feeders. Diversity in the inter-annual feeding strategies of humpback whales demonstrates the feeding plasticity of the species, but could also be indicative of changing dynamics within the Antarctic sea-ice ecosystem. This study presents the first investigation of trophodynamics in Southern hemisphere humpback whales derived from baleen plates, and further provides the first estimates of baleen plate elongation rates in the species.

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Potential energy gain by whales outside of the Antarctic: prey preferences and consumption rates of migrating humpback whales (Megaptera novaeangliae)

Cited by 42 publications

References 85 publications

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems

Southern Ocean biological iron cycling in the pre-whaling and present ecosystems

Interannual variability in the lipid and fatty acid profiles of east Australia-migrating humpback whales (Megaptera novaeangliae) across a 10-year timeline

Isotopic Evidence of a Wide Spectrum of Feeding Strategies in Southern Hemisphere Humpback Whale Baleen Records

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