Density-dependent and inter-specific interactions affecting European eel settlement in freshwater habitats |
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Authors: | Daniele Bevacqua M Andrello P Melià S Vincenzi G A De Leo and A J Crivelli |
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Institution: | (1) Dipartimento di Scienze Ambientali, Universit? degli Studi di Parma, Viale Usberti 33A, 43100 Parma, Italy;(2) Laboratoire d’Ecologie Alpine, Universit? Joseph Fourier, Grenoble, France;(3) Dipartimento di Elettronica e Informazione, Politecnico di Milano, Milan, Italy;(4) Station Biologique de la Tour du Valat, Le Sambuc, Arles, France |
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Abstract: | Identifying the factors influencing the settlement of European eel (Anguilla anguilla) juveniles in continental habitats is crucial to designing effective management and conservation measures for this endangered
species. A long-term data series (1993–2008) of European eel and European catfish (Silurus glanis) abundance in a freshwater canal of the Camargue water system (southern France), along with parallel data on water salinity
and glass eel abundance in the adjacent Vaccarès lagoon, was analysed to identify the possible causes of decline in eel abundance
observed in the canal during the last two decades. A model including glass eel recruitment and catfish abundance as covariates
explained 78% of the observed variation in eel settlement success. Results suggest that (1) salinity does not play a significant
role in determining the fraction of eels moving from the brackish lagoon to the canal; (2) density dependence affects settlement
success, possibly through a reduction of juvenile survival in the adjacent lagoon; and (3) catfish abundance is negatively
correlated with eel settlement. We discuss this latter point in terms of possible predation of catfish upon eels and/or inter-specific
competition between the two species. |
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