Exploring the future of the Coral Sea micronekton

Type Article
Date 2021-07
Language English
Author(s) Receveur Aurore1, 2, 3, Dutheil Cyril2, 4, Gorgues Thomas5, Menkes Christophe2, Lengaigne Matthieu6, Nicol Simon1, 7, Lehodey Patrick1, 8, Allain Valerie1, Menard Frederic3, Lebourges-Dhaussy Anne9
Affiliation(s) 1 : OFP/FEMA, Pacific Community, 95 Promenade Roger Laroque, BP D5, Nouméa, New Caledonia
2 : ENTROPIE, UMR 9220, IRD, Univ. de la Réunion, CNRS, 101 Promenade Roger Laroque, Nouméa, New Caledonia
3 : Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
4 : Department of Physical Oceanography and Instrumentation, IOW, Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany
5 : Univ. Brest, CNRS, Ifremer, IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM, F-29280, Plouzane, France
6 : MARBEC, University of Montpellier, CNRS, IFREMER, IRD, Sete, France
7 : Institute for Applied Ecology, University of Canberra, Bruce 2601, Australia
8 : CLS, Sustainable Fisheries, Marine Ecosystem Modelling, 11 rue Hermes, Ramonville, France
9 : IRD, Univ. Brest, CNRS, Ifremer, LEMAR, Campus Ifremer, BP70, Plouzane, France
Source Progress In Oceanography (0079-6611) (Elsevier BV), 2021-07 , Vol. 195 , P. 102593 (13p.)
DOI 10.1016/j.pocean.2021.102593
Keyword(s) Micronekton, Echosounder, Coral Sea, Climate change, Dynamical ecosystem model, Statistical ecosystem model

Ecosystem models forced by future climate simulations outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulate a substantial decline of tropical marine animal biomass over the course of the 21st century. Regional projections are however far more uncertain because of well-known biases common to most CMIP5 historical simulations that propagate within the food web. Moreover, the model outputs for high trophic levels marine fauna suffer from lack of validation based on in situ data. In this study, we implement a “bias-mitigation” strategy to reduce the physical oceanography and biogeochemical biases simulated by three CMIP5 models under the future RCP8.5 scenario. We force two very different micronekton models with these “bias-mitigated” outputs to infer the future micronekton changes in the Coral Sea: a 3-D deterministic population dynamics model; and a 3-D statistical model based on in situ hydro-acoustic data. These two models forecast a consistent pattern of micronekton abundance changes in the epipelagic layer (0–150 m) by 2100 for three different climate forcing used, with a marked decrease south of 22°S and a smaller increase further north mostly related to temperature and chlorophyll changes. In contrast, changes in the vertical patterns of micronekton predicted by the two models considerably differ in the upper mesopelagic layers (150–450 m) and lower mesopelagic layer (450–1000 m), highlighting the structural sensitivity in model type. Since micronekton are prey of all larger marine predators, those discrepancies in vertical structures of micronekton may hamper our potential to predict how top predators may evolve in the future.

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