MEPS 138:63-70 (1996)  -  doi:10.3354/meps138063

Tidal transport of Pectinaria koreni postlarvae (Annelida: Polychaeta) in the Bay of Seine (eastern English Channel)

Thiébaut E, Dauvin JC, Wang Z

Recent investigations on the recruitment of marine benthic invertebrates have highlighted the ability of postlarval and juvenile stages to re-enter the water column and undergo a consequent dispersal following primary settlement. In the eastern part of the Bay of Seine (English Channel), abundances of Pectinaria koreni postlarvae within the water column were measured hourly at 1 station over 2 time series of 93 and 92 h conducted in May 1991 and 1992 to determine the magnitude and frequency of postlarval transport and its dependency on current velocity and bottom shear stress. Postlarval numbers varied strongly with the state of the tide; mean densities were consistently larger, by at least one order of magnitude, during flood than during ebb. Maximum densities were observed with about a 2 h delay relative to the tidal current speed and bottom shear stress maxima. No diurnal rhythm of migratory activity was observed. The interaction of postlarval drifting and tide generates a net landward transport which could partly reduce the demographic consequences of larval dispersal. This mechanism is proposed to be one of the major processes which explain the spatial and temporal stability of the adult population in a highly advective and dispersive environment. The potential effects of other environmental factors (e.g. wind events) are also discussed.

Postlarval dispersal . Recruitment . Pectinaria koreni . English Channel

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