Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 13, issue 15
Biogeosciences, 13, 4533-4553, 2016
https://doi.org/10.5194/bg-13-4533-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 4533-4553, 2016
https://doi.org/10.5194/bg-13-4533-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 12 Aug 2016

Research article | 12 Aug 2016

Marine regime shifts in ocean biogeochemical models: a case study in the Gulf of Alaska

Claudie Beaulieu1, Harriet Cole1,a, Stephanie Henson2, Andrew Yool2, Thomas R. Anderson2, Lee de Mora3, Erik T. Buitenhuis4, Momme Butenschön3, Ian J. Totterdell5, and J. Icarus Allen3 Claudie Beaulieu et al.
  • 1Ocean and Earth Science, University of Southampton, Southampton, UK
  • 2National Oceanography Centre, Southampton, UK
  • 3Plymouth Marine Laboratory, Plymouth, UK
  • 4Tyndall Centre for Climate Change research, School of Environmental Sciences, University of East Anglia, Norwich, UK
  • 5Hadley Centre, Met Office, Exeter, UK
  • anow at: MSS Marine Laboratory, Marine Scotland Science, Aberdeen, UK

Abstract. Regime shifts have been reported in many marine ecosystems, and are often expressed as an abrupt change occurring in multiple physical and biological components of the system. In the Gulf of Alaska, a regime shift in the late 1970s was observed, indicated by an abrupt increase in sea surface temperature and major shifts in the catch of many fish species. A thorough understanding of the extent and mechanisms leading to such regime shifts is challenged by data paucity in time and space. We investigate the ability of a suite of ocean biogeochemistry models of varying complexity to simulate regime shifts in the Gulf of Alaska by examining the presence of abrupt changes in time series of physical variables (sea surface temperature and mixed-layer depth), nutrients and biological variables (chlorophyll, primary productivity and plankton biomass) using change-point analysis. Our results show that some ocean biogeochemical models are capable of simulating the late 1970s shift, manifested as an abrupt increase in sea surface temperature followed by an abrupt decrease in nutrients and biological productivity. Models from low to intermediate complexity simulate an abrupt transition in the late 1970s (i.e. a significant shift from one year to the next) while the transition is smoother in higher complexity models. Our study demonstrates that ocean biogeochemical models can successfully simulate regime shifts in the Gulf of Alaska region. These models can therefore be considered useful tools to enhance our understanding of how changes in physical conditions are propagated from lower to upper trophic levels.

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Regime shifts have been suggested in the late 1970s and late 1980s in the Gulf of Alaska with important consequences for fisheries. Here we investigate the ability of a suite of ocean biogeochemical models of varying complexity to simulate these regime shifts. Our results demonstrate that ocean models can successfully simulate regime shifts in the Gulf of Alaska region, thereby improving our understanding of how changes in physical conditions are propagated from lower to upper trophic levels.
Regime shifts have been suggested in the late 1970s and late 1980s in the Gulf of Alaska with...
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