Biology Faculty Articles

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Journal of Animal Ecology


biologging, hunting behaviour, marlin, oceanic front, oxygen minimum zone, pelagic predator, sailfish







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Pelagic predators must contend with low prey densities that are irregularly distributed and dynamic in space and time. Based on satellite imagery and telemetry data, many pelagic predators will concentrate horizontal movements on ephemeral surface fronts—gradients between water masses—because of enhanced local productivity and increased forage fish densities.
Vertical fronts (e.g. thermoclines, oxyclines) can be spatially and temporally persistent, and aggregate lower trophic level and diel vertically migrating organisms due to sharp changes in temperature, water density or available oxygen. Thus, vertical fronts represent a stable and potentially energy rich habitat feature for diving pelagic predators but remain little explored in their capacity to enhance foraging opportunities.
Here, we use a novel suite of high-resolution biologging data, including in situ derived oxygen saturation and video, to document how two top predators in the pelagic ecosystem exploit the vertical fronts created by the oxygen minimum zone of the eastern tropical Pacific.
Prey search behaviour was dependent on dive shape, and significantly increased near the thermocline and hypoxic boundary for blue marlin Makaira nigricans and sailfish Istiophorus platypterus, respectively. Further, we identify a behaviour not yet reported for pelagic predators, whereby the predator repeatedly dives below the thermocline and hypoxic boundary (and by extension, below the prey). We hypothesize this behaviour is used to ambush prey concentrated at the boundaries from below.
We describe how habitat fronts created by low oxygen environments can influence pelagic ecosystems, which will become increasingly important to understand in the context of global change and expanding oxygen minimum zones. We anticipate that our findings are shared among many pelagic predators where strong vertical fronts occur, and additional high-resolution tagging is warranted to confirm this.


© 2023 The Authors. Journal of Animal Ecology © 2023 British Ecological Society.

Journal of Animal Ecology articles that publish Open Access are published under the terms of the Creative Commons Attribution License. The CC BY license permits commercial and non-commercial re-use of an open access article as long as the author is properly attributed.

Research Funding

  • Batchelor Foundation Scholarship
  • Fish Florida Scholarship
  • Gallo-Dubois Scholarship
  • Guardians of the Eastern Tropical Pacific Seascape donor group
  • Guy Harvey Ocean Foundation. Grant Number: GHOF 2019-01
  • Nova Southeastern University

Additional Comments

Funding information: Batchelor Foundation Scholarship; Fish Florida Scholarship; Gallo-Dubois Scholarship; Guardians of the Eastern Tropical Pacific Seascape donor group; Guy Harvey Ocean Foundation, Grant/Award Number: GHOF 2019-01; Nova Southeastern University

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.




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