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Marine Ecology Progress Series

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MEPS 549:137-151 (2016)  -  DOI:

Abrupt shifts in the Gironde fish community: an indicator of ecological changes in an estuarine ecosystem

Xavier Chevillot1,*, Maud Pierre1, Arthur Rigaud1, Hilaire Drouineau1, Aurélie Chaalali2, Benoit Sautour3, Jérémy Lobry1

1Irstea, UR EABX, 50 Avenue de Verdun, 33612 Cestas Cedex, France
2Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer), Département Ecologie et Modèles pour l’Halieutique, Rue de l’île d’Yeu, BP 21105, 44311 Nantes, France
3Université Bordeaux, Environnements et Paléoenvironnements Océaniques et Continentaux, CNRS UMR 5805 (EPOC), Station Marine d’Arcachon, 2 rue du Pr. Jolyet, 33120 Arcachon, France
*Corresponding author:

ABSTRACT: For decades, global climate change has directly and indirectly affected the structure and function of ecosystems. Abrupt changes in biodiversity have been observed in response to linear or sudden modifications to the environment. These abrupt shifts can cause long-term reorganizations within ecosystems, with communities exhibiting new functional responses to environmental factors. Over the last 3 decades, the Gironde estuary in southwest France has experienced 2 abrupt shifts in both the physical and chemical environments and the pelagic community. Rather than describing these shifts and their origins, we focused on the 3 inter-shift periods, describing the structure of the fish community and its relationship with the environment during these periods. We described fish biodiversity using a limited set of descriptors, taking into account both species composition and relative species abundances. Inter-shift ecosystem states were defined based on the relationship between this description and the hydro-physico-chemical variables and climatic indices defining the main features of the environment. This relationship was described using generalized linear mixed models on the entire time series and for each inter-shift period. Our results indicate that (1) the fish community structure has been significantly modified, (2) environmental drivers influencing fish diversity have changed during these 3 periods, and (3) the fish-environment relationships have been modified over time. From this, we conclude a regime shift has occurred in the Gironde estuary. We also highlight that anthropogenic influences have increased, which re-emphasizes the importance of local management in maintaining fish diversity and associated goods and services within the context of climate change.

KEY WORDS: Ecosystem state · Fish diversity · Estuary · Generalised linear mixed models ·∙ GLMM · Time series · Shift · Inter-shift periods

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Cite this article as: Chevillot X, Pierre M, Rigaud A, Drouineau H, Chaalali A, Sautour B, Lobry J (2016) Abrupt shifts in the Gironde fish community: an indicator of ecological changes in an estuarine ecosystem. Mar Ecol Prog Ser 549:137-151.

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