Artificial daily fluctuations of river discharge affect the larval drift and survival of a tropical amphidromous goby.
Les fluctuations quotidiennes artificielles du débit des rivières affectent la dérive larvaire et la survie d'un gobie amphidrome tropical
Lagarde, R. ; Teichert, N. ; Faivre, L. ; Grondin, H. ; Magalon, H. ; Pirog, A. ; Valade, P. ; Ponton, D.
Type de document
Article de revue scientifique à comité de lecture
Affiliation de l'auteur
HYDRO REUNION ETANG SALE FRA ; IRSTEA BORDEAUX UR EABX FRA ; HYDRO REUNION ETANG SALE FRA ; HYDRO REUNION ETANG SALE FRA ; ENTROPIE UNIVERSITE DE LA REUNION IRD CNRS LABORATOIRE D'EXCELLENCE CORAIL SAINT DENIS FRA ; ENTROPIE UNIVERSITE DE LA REUNION IRD CNRS LABORATOIRE D'EXCELLENCE CORAIL SAINT DENIS FRA ; OCEA CONSULT RAVINE DES CABRIS FRA ; ENTROPIE UNIVERSITE DE LA REUNION IRD CNRS LABORATOIRE D'EXCELLENCE CORAIL SAINT DENIS FRA
Résumé / Abstract
Amphidromous fish species reproduce in rivers, and their larvae immediately drift to the sea after hatching. Most of these larvae survive in freshwater for a few days only, rapidly reaching sea water is thus essential. Being of small size, especially among species of the Sicydiinae subfamily, the larvae possess poor swimming abilities; their drift dynamics is considered to be mainly passive and influenced by flow conditions. The influence of daily fluctuations in flow regime on Sicyopterus lagocephalus (Sicydiinae) larval drift patterns was studied using drift nets at three sites along the dammed Langevin River in Reunion Island. The river flow was stable at the upstream site when frequent anthropogenic river flow fluctuations were observed at the two sites downstream to the dam. Weak diel larval drift dynamics were detected at the upstream site and the first site under anthropogenic river flow conditions. In contrast, larval drift dynamics at the most downstream site was strongly influenced by anthropogenic daily fluctuations of discharge: the abundance of drifting larvae increased with peaks of discharge, regardless of the time. As higher mortality rates of drifting larvae were observed during discharge peaks, the benefit of a more rapid travel to the ocean associated with these peaks should be lower than expected. It is concluded that peaks of discharge increase the number of larvae drifting to the sea probably due to higher physical constraints on the egg clutches, but also decrease the chance of survival for larvae that may be nonfully developed.
Ecology of Freshwater Fish, vol. 27, p. 646 - 659