Répartition verticale des larves de Pectinaria koreni en baie de Seine orientale : influence sur le transport et le recrutement
Variations in recruitment of benthic invertebrate species with pelagic larvae, which inhabit estuaries, can be reduced by the vertical distribution of larvae. In fact, they may be located in water masses in which net transport favours retention in the vicinity of estuaries. Such a hypothesis can explain the Pectinaria koreni population stability in the western bay of Seine. The vertical distribution of P. koreni larvae is in relation to the turbulence level. When turbulence is low, strong water stratification is present, and larvae are then most abundant under the halocline (in water masses where salinity is more than 30.5). Moreover, a strong ontogenetic migration is observed : young larvae occupy the upper part of the water column and old larvae the bottom part. In the second situation, when turbulence is high, water stratification is destroyed, and larvae are evenly distributed throughout the entire water column. Furthermore, no ontogenetic migration is found. It may thus be concluded that larval transport or retention depend on turbulence level. When turbulence is low, larvae can be retained near the estuary : either larvae are just above the depth where net transport is nul, in which case they are carried slightly seaward; or they are below this depth and net transport is landward, in which case they contribute to recruitment and stability of the western Bay of Seine population. On the other hand, when turbulence is high, larvae can be flushed out of the eastern bay of Seine.
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Mots clés :
VERTICAL DISTRIBUTION, PECTINARIA-KORENI, LARVAL TRANSPORT, RECRUITMENT, BAY OF SEINE
Thème (issu du Text Mining) :
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1992 , Vol. 15 , N. 1 , P. 95-104