Changes in the distribution of copepods in the Gironde estuary: A warming and marinisation consequence?

Chaalali, Aurélie; Chevillot, Xavier; Beaugrand, Grégory; David, Valérie; Luczak, Christophe; Boët, Philippe; Sottolichio, Aldo; Sautour, Benoît

doi:10.1016/j.ecss.2012.12.004

Cited by 38 publications

(15 citation statements)

References 55 publications

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“…1), extending 70 km from its mouth at Royan to the confluence of the Garonne and Dordogne Rivers. The historical upstream salinity limit (where salinity = 0) used to be situated around the zone of confluence of the 2 rivers during low water periods, but has been moving upstream for the last few years as a result of the marinisation process (Chaalali et al 2013c). The current salinity limit during summer is located near the city of Bordeaux, almost 25 km upstream along the Garonne River (authors' unpubl.…”

Section: Study Sitementioning

confidence: 99%

“…First termed by David et al (2007) and later used in several papers (Pasquaud et al 2012, Chaalali et al 2013a, it describes the process whereby marine waters flow far upstream into the Gironde basin, and thus into the continent, due to a drop in river discharge caused by the synergistic effect of reduced precipitation in the catchment area and increased water uptake for irrigated agriculture. The annual mean salinity has significantly increased in all sections of the estuary, though the trend is more perceptible in the downstream sections (Chaalali et al 2013c). Consequently, this marinisation has led to a progressive increase in the number of marine fish species in the estuarine area (Pasquaud et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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

Chevillot¹,

Pierre²,

Rigaud³

et al. 2016

Mar. Ecol. Prog. Ser.

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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.

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Section: Study Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Chevillot¹,

Pierre²,

Rigaud³

et al. 2016

Mar. Ecol. Prog. Ser.

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“…Changes due to climate changes were also not ruled out by these authors. Similarly, CHAALALI et al (2013) reported changes in the longitudinal distribution of copepods as a consequence of marinisation in the Gironde estuary, the largest estuary in southwestern Europe. SILVA et al (2004) also found changes in the copepod species composition associated with marinisation in an estuarine area (Suape bay) in northeastern Brazil.…”

Section: Discussionmentioning

confidence: 99%

“…an increased intrusion of marine waters, e.g. CHAALALI et al, 2013) of PAC and PIR in the dry season led to changes in the species composition, with an emergence of marine species and a decrease in phytoplankton biomass. LACERDA et al (2007) ) mostly due to alterations in freshwater supply and sediment accumulation in consequence of river damming.…”

Section: Discussionmentioning

confidence: 99%

Influence of river discharge on phytoplankton structure and nutrient concentrations in four tropical semiarid estuaries

2016

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This study evaluated changes in phytoplankton and nutrients after an increase in river discharge in four estuaries of northeastern Brazil. Samples were taken during a markedly freshwater-deprived period (Nov/2010, dry season), and during a rainy season (May/2011). While two estuaries are located in urban areas (Ceará -CE and Cocó -CO), the others are markedly freshwater-deprived (Pacoti -PAC and Pirangi -PIR). Our findings indicate that increased freshwater had opposing effects on estuaries impacted by anthropogenic discharges (CO, CE and PIR) compared with the other, less impacted (PAC). In CO and CE, the freshwater flow during the rainy period had a nutrient diluting effect and controlled phytoplankton blooms. In PIR, only phosphorus and inorganic nitrogen decreased in the rainy season. In contrast, an increase of all nutrients was observed in PAC, and of TN in PIR, followed by an increase in phytoplankton biomass. In the rainy season, eutrophic freshwater species dominated in all the estuaries. In the dry season, blooms of Cryptomonas/Rhodomonas and Synechocystis aquatilis were, respectively, observed in CE and CO. Also in the dry season, PAC and PIR had a predominance of marine species under a condition of hypersalinity. Canonical correspondence analysis suggested the variation observed for salinity, silica, and TN are the main driver of phytoplankton structure. AbstrAct

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“…Ceci tend à démontrer qu'une remontée effective du bouchon vaseux en étiage s'est produite sur 40 ans, par le seul fait de l'évolution de la topographie fluviale, qui a modifié la propagation de la marée et, en conséquence le transport des sédiments. D'autres travaux ont montré une "marinisation" de l'estuaire aval sur les trente dernières années (CHAALALI et al, 2013), qui serait attribuée à un effet climatique global ou régional. Nos résultats, très préliminaires, suggèrent qu'il peut exister, au moins, une superposition de ces effets globaux avec des effets locaux anthropiques, dûs aux modifications du lit de la Garonne et de la Dordogne.…”

Section: Bouchon Vaseux Simuléunclassified

Evolution hydrosédimentaire récente de l'estuaire de la Gironde. Apport d’un modèle de transport

Sottolichio¹,

Hanquiez²,

Maanen³

et al. 2014

XIIIèmes JNGCGC Dunkerque

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Résumé :La modélisation 3D de la turbidité en estuaire et les applications à des systèmes réels se sont beaucoup développées ces dernières années. Toutefois, si la validation du calcul hydrodynamique 3D est relativement aisée, la calibration sédimentaire est beaucoup plus compliquée. Pour ces raisons, encore peu de modélisations ont tenté de quantifier les bilans sédimentaires basés sur la dynamique saisonnière du bouchon vaseux. Dans cette communication, nous présentons une modélisation de l'estuaire de la Gironde, avec en particulier un essai de validation du bouchon vaseux grâce aux mesures et observations spatiales récentes et disponibles. Nous montrons que les bilans sédimentaires sont très sensibles au paramétrage de la vitesse de chute, qui peut être ajustée par l'examen de la stabilité de la turbidité à moyen terme. Enfin, nous discutons de l'évolution hydrosédimentaire de la Gironde à plus long terme par l'application du modèle dans deux configurations bathymétriques récentes des fleuves. Leur comparaison montre que des effets anthropiques locaux ont pu contribuer à une remontée du bouchon vaseux dans les fleuves à l'échelle de 50 ans, indépendamment de tout effet climatique global ou régional. Mots-clés : Dynamique sédimentaire, Estuaire de la Gironde, Modèle, Bouchon vaseux. IntroductionLa modélisation 3D de la turbidité en estuaire s'est beaucoup développée ces dernières années, et les applications à des systèmes réels ont permis de décrire le bouchon vaseux ou de quantifier des flux en suspension dans plusieurs environnements (PARK et al., 2008 ;SOUZA et al., 2012). Le calcul 3D est indispensable car les modèles intégrés sur la verticale (2DH) ne peuvent pas restituer les gradients verticaux ni les stratifications de densité. Toutefois, si la validation du calcul hydrodynamique (courants moyens) est relativement aisée, la calibration sédimentaire est plus compliquée car la concentration est contrôlée par plusieurs paramètres dépendant des propriétés des sédiments. Pour ces raisons, encore peu de modélisations ont tenté de quantifier les bilans sédimentaires saisonniers.

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Changes in the distribution of copepods in the Gironde estuary: A warming and marinisation consequence?

Cited by 38 publications

References 55 publications

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

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

Influence of river discharge on phytoplankton structure and nutrient concentrations in four tropical semiarid estuaries

Evolution hydrosédimentaire récente de l'estuaire de la Gironde. Apport d’un modèle de transport

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