Ten-year observation of the Gironde tributary fluvial system: fluxes of suspended matter, particulate organic carbon and cadmium

Schäfer, Jörg; Blanc, Guillaume; Lapaquellerie, Yvon; Maillet, N.; Maneux, Eric; Etcheber, H.

doi:10.1016/s0304-4203(02)00066-x

Cited by 113 publications

(54 citation statements)

References 21 publications

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“…The most striking example is the Ebro River where the recent sediment flux (0.092 × 10 6 t yr −1 ) represents less than 1 % of what was transported before the period of dam constructions (Tena et al, 2011). In comparison, two other French rivers (Garonne River and Dordogne River) flowing into the Gironde estuary exhibited TSM (2.4 × 10 6 t yr −1 and 0.8 × 10 6 t yr −1 , respectively) and POC (7.2 × 10 4 t yr −1 and 4.7 × 10 4 t yr −1 , respectively) fluxes, varying within the same ranges as our Rhône River fluxes (Schäfer et al, 2002). Pont et al (2002) estimated that Rhône floods with return period higher than one year accounted for 77 % of the TSM export.…”

Section: Biogeosciencessupporting

confidence: 63%

Biogeochemical characterization of the riverine particulate organic matter transferred to the NW Mediterranean Sea

et al. 2014

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Abstract.A large amount of terrestrial organic matter is annually delivered by rivers to the continental shelf, where this material is either degraded, buried or transferred to the deep sea by hydrodynamic processes such as storms. The relative amount of terrestrial organic matter in the marine sediments is often determined by analysing the stable isotopes (δ 13 C and δ 15 N) and the C / N ratio of organic matter because the various particulate organic matter (POM) sources have distinct isotopic compositions. With the objective to refine and better interpret POM sources in the marine environment, we have characterized monthly terrestrial POM delivered by eight rivers discharging to the NW Mediterranean Sea: the Rhône, Hérault, Orb, Aude, Têt, Fluvià, Ter and Tordera rivers. These rivers were simultaneously sampled from November 2008 to December 2009 and the concentrations of total suspended matter (TSM), particulate organic carbon (POC) and nitrogen (PN), as well as their stable isotopic ratios (δ 13 C and δ 15 N) were determined.During the survey, three rainstorm events with winds coming from the E-NE and the S-SE impacted the NW Mediterranean. Depending on the direction of incoming winds, the fluvial response (amount of water discharge and TSM) was different. Rivers draining the Alps (Rhône River) and Central Massif (Hérault, Orb, and Aude rivers) were mostly impacted by rainstorms associated with winds coming from the S-SE, while rivers draining the Pyrenees (Têt, Fluvià, and Ter rivers) and the Montseny Massif (Tordera River) were impacted by rainstorms associated with winds coming from the E-NE. In addition, the spatial evolution of water discharges shows a different hydrological regime of the Rhône River, with relatively constant and high water stages and TSM concentrations when compared to coastal rivers, characterized by long periods of low water stages. TSM concentrations are positively correlated to water discharges (high water flows resuspended riverbed sediments) but show an inverse relationship with POC and PN relative contents (mostly due to dilution and by low availability of light in river waters during flood events). TSM in most of the coastal rivers have on average 2.5-3 times higher POC and PN mean contents than the Rhône River (8.5 and 1.5 %, respectively, for coastal rivers compared to 3.6 and 0.5 %, respectively, for the Rhône River). This discrepancy may be caused by the long drought periods in small coastal Mediterranean watersheds that enhance the eutrophication in studied coastal rivers. The δ 13 C ratios of organic matter also reflect this discrepancy between high and low water stages with values ranging from −33.2 to −24.5 ‰. The enriched 13 C values (−26.3 ± 0.4 ‰ for the Rhône River and −26.9 ± 1.2 ‰ for coastal rivers), measured during high water stages, express mostly a mixture of terrestrial source (plant remains and soils) whereas

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Section: Biogeosciencessupporting

confidence: 63%

Biogeochemical characterization of the riverine particulate organic matter transferred to the NW Mediterranean Sea

et al. 2014

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“…Schäfer et al (2002) showed the period of time between flooding and inundation will affect organic matter and suspended solids export. We observed that during two similar sized floods that occurred on the Bega and Clyde Rivers during March 2012, DOC concentrations at the upper most station were 13 and 11 mg L -1 respectively during the first flood, and 11 and 7 mg L -1 respectively during a flood ten days later (Fig.…”

Section: 5)mentioning

confidence: 99%

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Hitchcock

Mitrovic

2015

Estuarine, Coastal and Shelf Science

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Freshwater inflows play a key role in the delivery of organic carbon to estuaries. However, our understanding of the dynamics between discharge and carbon globally is limited. In this study we performed a 30-month monitoring study on the Bega and Clyde River estuaries, Australia, to understand the influence that discharge had on carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics. We hypothesised that 1) discharge would be the most important factor influencing carbon and nutrient concentrations, though during low flows chlorophyll a would also be positively related to carbon, 2) bacteria would be related to dissolved organic carbon (DOC), and chlorophyll a to temperature, nitrogen and phosphorus, and 3) that concentrations of carbon, nitrogen, phosphorus, bacterial biomass and chlorophyll a would be significantly different between large 'flood flows', smaller 'fresh flows' and base flow conditions. We found that discharge was always the most important factor influencing carbon and nutrient concentrations, and that primary production appeared to have little influence on the variation in DOC concentration even during base flow conditions. We suggest this relationship is likely due to highly episodic discharge that occurred during the study period. Bacteria were related to DOC in the lower estuary sites, but phosphorus in the upper estuary. We suggest this is likely due to the input of bioavailable carbon in the upper estuary leading bacteria to be P limited, which changes downstream to carbon limitation as DOC becomes more refractory. Chlorophyll a was positively related to temperature but not nutrients, which we suggest may be due to competition with bacteria for phosphorus in the upper estuary. Carbon, nitrogen and phosphorus concentrations were different under flood, fresh and base flow conditions, though these differences sometimes varied between estuary locations for different resources. Overall, the results demonstrate that discharge plays an important structuring role for carbon, nutrient and bacteria dynamics on the Bega and Clyde Rivers, and that the differences observed between flood and fresh inflows suggest that further study into the influence of differently sized inflow events is important.

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“…In addition to this, river flow in the Gironde system had a strong negative relationship with temperature in recent decades (r 2 = 0.37, p < 0.001; data provided by Centre Nucléaire de Production d'Électricité du Blayais). Large temporal variations in river flow were found in this system during the past decade (Schäfer et al 2002), and the lowest river flow during the hottest summer can be explained by climate-related agricultural water use in this region. It seems convincing that the higher temperatures associated with low amounts of river discharge could potentially produce adverse effects, such as lower oxygen concentrations and higher contaminant concentrations.…”

Section: Discussionmentioning

confidence: 81%

Modeling individual growth trajectories of the female European eel in relation to temperature and habitat-use history in the Gironde River, France

Yokouchi¹,

Daverat²

2013

Aquat. Biol.

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Although the average growth rate of European eel is known to be generally dependent on temperature and habitat at the population scale, large variation in growth among eels in a single river basin can also be widely observed. In this study, individual growth trajectories of female European eels in the Gironde River basin, France, were modeled with habitat-use histories and thermal variations in relation to regional climatic events such as the heat wave in 2003 observed in SW Europe. A mixed-effects model was used to take into account the repeated measures of individual growth of 173 female eels in 1993 to 2003, obtained from otolith structure and chemistry. Temperature effect was tested using a proxy of efficient temperature for growth between 2 thermal thresholds in a year. The models with thresholds for growth between 12 and 15°C (lower) and 18°C (higher) were selected considering Akaike's information criterion. Individual annual growth estimates were higher in the estuary habitat than in the river habitat. Estimated growth was higher when eels shifted habitats between freshwater and brackish water or seawater. The years 1999 and 2001 had, respectively, the lowest and highest temperature proxy value, showing that a longer growing season (moderate summer/warm winter) had a positive effect on growth. The 2003 heat wave had a negative effect on eel growth, reflected by the lower temperature proxy value. The same approach could be used in the future to estimate the effect of global climate change on the growth and distribution of eels at local and regional scales.KEY WORDS: Anguilla anguilla · Inter-annual temperature variation · Habitat-use history · Mixed-effects model Aquat Biol 19: 185-193, 2013 reproductive stage. The European eel forms a unique population from a genetic perspective (reviewed by Tesch 2003, Aoyama 2009, making the eel a model of choice to study the effects of environment on lifehistory traits. Thus, one can expect that eel growth traits respond to drivers such as temperature and habitat productivity, which can be partly determined by the passive transport of larvae from the spawning ground to the continental growth habitat. The growth phase of eels is very plastic, as eels may occupy many different environments along a large latitudinal gradient . Resale or republication not permitted without written consent of the publisherAnguillid eels have several habitat-use patterns as shown by otolith microchemistry. While some eels spend their whole growth phase in freshwater, others remain in brackish or seawater (Tsukamoto et al. 1998). In addition, some eels change habitats during their growth phase (e.g. Tsukamoto et al. 1998, Tsukamoto & Arai 2001, Jessop et al. 2004, Daverat & Tomas 2006, Kaifu et al. 2010, Yokouchi et al. 2012. Studies on growth of anguillid eels showed that eels living in brackish habitats had a higher growth rate than eels living in freshwater habitats (e.g. Helfman et al. 1987, Morrison & Secor 2003, Melia et al. 2006, Yokouchi et al. 2008). Models of eel growth...

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Ten-year observation of the Gironde tributary fluvial system: fluxes of suspended matter, particulate organic carbon and cadmium

Cited by 113 publications

References 21 publications

Biogeochemical characterization of the riverine particulate organic matter transferred to the NW Mediterranean Sea

Biogeochemical characterization of the riverine particulate organic matter transferred to the NW Mediterranean Sea

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Modeling individual growth trajectories of the female European eel in relation to temperature and habitat-use history in the Gironde River, France

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