Overview of BLOOFINZ/INDITUN investigations of the southern bluefin spawning region off northwest Australia, January–March 2022

Southern Bluefin Tuna (SBT, Thunnus maccoyii ) range broadly in rich feeding grounds of the Southern Hemisphere but spawn only in a small tropical region off northwestern Australia directly downstream of the Indonesian Throughflow. Here, we describe goals, physical context, design and major findings of an end-to-end process study conducted during the peak SBT spawning season (January-March 2022) to understand nutrient sources, productivity, pelagic food web structure and their relationships to larval SBT feeding, growth and survival. Mesoscale variability was investigated by continuous underway measurements of surface waters and station sampling along the cruise track. Biogeochemical and community relationships, process rates, and trophic interactions were determined in four multi-day Lagrangian experiments in the southern Argo Basin. The study revealed strong system balances among nitrogen fluxes, phytoplankton production, grazing processes, and export. Highly selective feeding on appendicularians allows efficient trophic transfer from picophytoplankton-dominated production to SBT larvae. Plankton productivity, phytoplankton carbon and zooplankton biomass were proportionately elevated compared to similar measurement from the Atlantic bluefin larval habitat in the Gulf of Mexico, but with less advective input from the coastal margins. Individual-based otolith and stable isotope analyses identify larvae of low trophic position, narrow diet, and narrow maternal diet as the fastest growers most likely to contribute to stock recruitment. Our study highlights the importance of system-level studies to document and understand the subtleties of how food webs of oligotrophic regions respond to climate change, which may not be predictable from the acquired knowledge of historical studies.

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Publication Details

Journal
Deep Sea Research Part II Topical Studies in Oceanography
Published
2025-11-09
DOI
https://doi.org/10.1016/j.dsr2.2025.105564
Citations
2
Primary Topic
Marine and fisheries research
Type
article
Field-Weighted Citation Impact
2.21

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article

Overview of BLOOFINZ/INDITUN investigations of the southern bluefin spawning region off northwest Australia, January–March 2022

Claire H. Davies, Estrella Malca, David J. Die, Natalia Yingling et al.
2 citations
Deep Sea Research Part II Topical Studies in Oceanography
Marine and fisheries research
2.21
article

Overview of BLOOFINZ/INDITUN investigations of the southern bluefin spawning region off northwest Australia, January–March 2022

Claire H. Davies, Estrella Malca, David J. Die, Natalia Yingling, Moira Décima, Karen E. Selph, Rasmus Swalethorp, Claudia Traboni, Andrew E. Allen, J.M. Quintanilla-Hervás, Sven A. Kranz, L.E. Beckley, Michael R. Landry, Grace Cawley, Barbara Muhling, Thomas Kelly, Michael R. Stukel, Opeyemi Kehinde, Nicolas Cassar, Christian K. Fender, Robert H. Lampe, Akihiro Shiroza, Joaquim I. Goés, Raúl Láiz-Carrión, María Grazia Pennino, Patricia Romero-Fernández, Ricardo Borrego‐Santos, Manon Laget, Hongbin Liu, Shuai Gu, A. DeSouza, Justin Rose, Tristan Biard, Luke Matisons, Kai Hong Io, Lindsey E. Kim, Alejandro Jivanjee
article en
2 citations

Abstract

Southern Bluefin Tuna (SBT, Thunnus maccoyii ) range broadly in rich feeding grounds of the Southern Hemisphere but spawn only in a small tropical region off northwestern Australia directly downstream of the Indonesian Throughflow. Here, we describe goals, physical context, design and major findings of an end-to-end process study conducted during the peak SBT spawning season (January-March 2022) to understand nutrient sources, productivity, pelagic food web structure and their relationships to larval SBT feeding, growth and survival. Mesoscale variability was investigated by continuous underway measurements of surface waters and station sampling along the cruise track. Biogeochemical and community relationships, process rates, and trophic interactions were determined in four multi-day Lagrangian experiments in the southern Argo Basin. The study revealed strong system balances among nitrogen fluxes, phytoplankton production, grazing processes, and export. Highly selective feeding on appendicularians allows efficient trophic transfer from picophytoplankton-dominated production to SBT larvae. Plankton productivity, phytoplankton carbon and zooplankton biomass were proportionately elevated compared to similar measurement from the Atlantic bluefin larval habitat in the Gulf of Mexico, but with less advective input from the coastal margins. Individual-based otolith and stable isotope analyses identify larvae of low trophic position, narrow diet, and narrow maternal diet as the fastest growers most likely to contribute to stock recruitment. Our study highlights the importance of system-level studies to document and understand the subtleties of how food webs of oligotrophic regions respond to climate change, which may not be predictable from the acquired knowledge of historical studies.

Deep Sea Research Part II Topical Studies in OceanographyVol. 224
Florida State University (US), University of Hawaiʻi at Mānoa (US), CSIRO Oceans and Atmosphere (AU), Dalhousie University (CA), University of Miami (US), Scripps Institution of Oceanography (US), Lamont-Doherty Earth Observatory (US), Duke University (US), Murdoch University (AU), Stazione Zoologica Anton Dohrn (IT), Instituto Español de Oceanografía (ES), Institut Català de Ciències del Clima (ES), Laboratoire d’Océanologie et de Géosciences (FR), Rice University (US)
National Science Foundation, Ministerio de Ciencia, Innovación y Universidades, Australian Government, Ministerio de Ciencia e Innovación
Openalex Percentile: Top 11%
Marine and fisheries research
2.21
DOIOpen Access PDFOpenAlex
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