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Signals from the south; humpback whales carry messages of Antarctic sea‐ice ecosystem variability
Author(s) -
Bengtson Nash Susan M.,
Castrillon Juliana,
Eisenmann Pascale,
Fry Brian,
Shuker Jon D.,
Cropp Roger A.,
Dawson Amanda,
Bignert Anders,
BohlinNizzetto Pernilla,
Waugh Courtney A.,
Polkinghorne Bradley J.,
Dalle Luche Greta,
McLagan David
Publication year - 2018
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14035
Subject(s) - humpback whale , krill , baleen , marine ecosystem , antarctic krill , oceanography , euphausia , ecosystem , environmental science , southern hemisphere , climate change , apex predator , trophic level , whale , fishery , ecology , biology , geology
Southern hemisphere humpback whales ( Megaptera novaeangliae ) rely on summer prey abundance of Antarctic krill ( Euphausia superba ) to fuel one of the longest‐known mammalian migrations on the planet. It is hypothesized that this species, already adapted to endure metabolic extremes, will be one of the first Antarctic consumers to show measurable physiological change in response to fluctuating prey availability in a changing climate; and as such, a powerful sentinel candidate for the Antarctic sea‐ice ecosystem. Here, we targeted the sentinel parameters of humpback whale adiposity and diet, using novel, as well as established, chemical and biochemical markers, and assembled a time trend spanning 8 years. We show the synchronous, inter‐annual oscillation of two measures of humpback whale adiposity with Southern Ocean environmental variables and climate indices. Furthermore, bulk stable isotope signatures provide clear indication of dietary compensation strategies, or a lower trophic level isotopic change, following years indicated as leaner years for the whales. The observed synchronicity of humpback whale adiposity and dietary markers, with climate patterns in the Southern Ocean, lends strength to the role of humpback whales as powerful Antarctic sea‐ice ecosystem sentinels. The work carries significant potential to reform current ecosystem surveillance in the Antarctic region.