Evidence of silver eels contamination by microcystin‐LR at the onset of their seaward migration: what consequences for breeding potential?

Acou, Anthony; Robinet, Tony; Lance, Emilie; Gérard, Claudia; Mounaix, Béatrice; Brient, Luc; Rouzic, Bertrand Le; Feunteun, Éric

doi:10.1111/j.1095-8649.2007.01726.x

Cited by 19 publications

(18 citation statements)

References 50 publications

(52 reference statements)

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“…Levels of Microcystin‐LR, the most common and toxic compounds associated with cyanobacterial blooms, were recently analysed in fresh liver of 30 migrant silver eels caught at the onset of their seaward migration. Results showed that 50% of them were contaminated and that contaminated silver eels had significantly lower condition factors (Acou et al. 2008).…”

Section: Discussionmentioning

confidence: 99%

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Migration pattern of silver eel (Anguilla anguilla, L.) in an obstructed river system

Acou¹,

Laffaille²,

Legault³

et al. 2008

Ecology of Freshwater Fish

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International audienceThe downstream migration of European silver eels in the River Frémur was examined to determine the potential effects of the numerous migration barriers that exist on waterways in western France. The Frémur has a 14 m high dam which creates a 3 × 106 m3 water supply reservoir, 6 km from tidal limit. Based on 8-year records (1996–2004) of migrant silver eels captured in a Wolf trap located about 1 km below the dam, the influence of this dam on the migration was examined. These records indicate that 91% of silver eels were captured when the dam was overtopped (i.e. when the water reservoir was full). The timings of the overflow periods varied greatly between years mainly because they are function of the duration of the filling period which in turn is dependent on the level of summer water abstraction and annual hydrological conditions. Consequently, migration periods occurred at variable dates (between November and April) which is late in comparison with nonobstructed European river systems (generally between August and December). During overflow periods the migration of silver eels increased markedly during rain events (increasing river flow). This indicates that flow flushes, are essential so that settled silver eels can orientate themselves and pass over the dam. The hypothesis of a 'dam effect' that could stop temporarily or permanently some of silver eels in the reservoir is discussed. Finally, the influence of the migration delays on the condition of silver eels is considere

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Section: Discussionmentioning

confidence: 99%

“…2008). Direct influence of toxins on eel metabolism and/or the increased energy demand required for the detoxification process are probably the two key factors that explain this effect (Acou et al. 2008).…”

Section: Discussionmentioning

confidence: 99%

Migration pattern of silver eel (Anguilla anguilla, L.) in an obstructed river system

Acou¹,

Laffaille²,

Legault³

et al. 2008

Ecology of Freshwater Fish

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“…The effect of the morphological index on individual body condition was tested using a mixed linear model to account for the structure of the dataset, for eel growth not being isometric and for body condition being correlated to TL (e.g. Acou et al 2008). The model was built using W (log-transformed) as the response variable, each capture or recapture as the replicate unit (n = 99) and individual identity as the random variable.…”

Section: Body Conditionmentioning

confidence: 99%

Fitness consequences of individual specialisation in resource use and trophic morphology in European eels

et al. 2011

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Individual specialisation can lead to the exploitation of different trophic and habitat resources and the production of morphological variability within a population. Although the ecological causes of this phenomenon are relatively well known, its consequences on individual fitness are less recognised. We have investigated the extent of individual specialisation in resource use and trophic morphology and its fitness consequences through a combination of tagging-recapture, stable isotope analyses and telemetry. The European eel (Anguilla anguilla) was the model species as it displays significant variability in head shape. Independent to their body length, individuals with broader heads displayed a significantly higher trophic position (δ(15)N) than individuals with narrower heads. This corresponded with a significantly higher proportion of prey fish in their diet compared with invertebrates and was associated with the use of a habitat niche located further from the river bank. The European eel therefore provides a rare empirical example of individual specialisation in resource use and trophic morphology in a natural population occurring at a very small spatial scale. Individuals with intermediate head morphology displayed lower body condition (a proxy of fitness) than individuals with extreme head morphology (i.e. narrower and broader headed individuals), demonstrating the existence of disruptive selection associated with individual specialisation.

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“…in press). For instance, pollution or parasitism might severely lower individual fitness by reducing the fecundity or the probability of reaching the Sargasso Sea (Robinet & Feunteun 2002; EELREP 2005; Acou et al. 2008).…”

Section: Introductionmentioning

confidence: 99%

European eel distribution and body condition in a river floodplain: effect of longitudinal and lateral connectivity

Lasne

Acou

Vila‐Gispert

et al. 2008

Ecology of Freshwater Fish

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International audienceWe studied eel population characteristics (size classes, densities and body condition) in the lower Loire River floodplain (France) to evaluate the effects of longitudinal and lateral gradients. A total of 36 sites were electrofished in June 2005. The sites were grouped first into three river segments according to the distance inland corresponding to a longitudinal gradient and secondly into three lateral connectivity categories. Results indicate that small eels, especially those ≤300 mm, were very abundant downstream but density rapidly decreased upstream. In addition, eels ≤150 mm tended to be most abundant in connected waterbodies. Conversely, the distribution of larger eels was quite uniform across both dimensions. Eel condition decreased upstream. In parallel, in downstream river segment, eels had a lower condition in disconnected waterbodies than in connected ones. Eel specialists still have only a longitudinal perception of eel habitat. Our results suggest that lateral gradients should be also taken into consideratio

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Evidence of silver eels contamination by microcystin‐LR at the onset of their seaward migration: what consequences for breeding potential?

Cited by 19 publications

References 50 publications

Migration pattern of silver eel (Anguilla anguilla, L.) in an obstructed river system

Migration pattern of silver eel (Anguilla anguilla, L.) in an obstructed river system

Fitness consequences of individual specialisation in resource use and trophic morphology in European eels

European eel distribution and body condition in a river floodplain: effect of longitudinal and lateral connectivity

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