A MODEL OF LARVAL DISPERSION COUPLING WIND-DRIVEN CURRENTS AND VERTICAL LARVAL BEHAVIOR - APPLICATION TO THE RECRUITMENT OF THE ANNELID OWENIA-FUSIFORMIS IN BANYULS BAY, FRANCE
C. Verdierbonnet et al., A MODEL OF LARVAL DISPERSION COUPLING WIND-DRIVEN CURRENTS AND VERTICAL LARVAL BEHAVIOR - APPLICATION TO THE RECRUITMENT OF THE ANNELID OWENIA-FUSIFORMIS IN BANYULS BAY, FRANCE, Marine ecology. Progress series, 160, 1997, pp. 217-231
We present a mathematical model of larval dispersal into a coastal zon
e dominated by wind-driven currents: larvae are considered as active p
articles tracked by the 3-D (3-dimensional) velocities calculated by a
physical model sophisticated enough to give a good representation of
the 3-D structure of wind-driven currents. As an application, we model
the larval recruitment of the annelid Owenia fusiformis in Banyuls Ba
y, France, located at the southwest extremity of the Gulf of Lions. Th
e currents are generated by the permanent offshore Liguro-Provencal ci
rculation and by time-varying winds, the swimming behaviour of larvae
is assumed to be only vertical, the spawning zones are in 2 adjacent b
ays and the pelagic phase lasts about 4 wk. Larvae are assumed to be s
uccessfully recruited if they settle after pelagic morphological chang
es on the substratum suitable to their benthic development. Larvae whi
ch do not belong to the successful recruitment either settle too young
on the suitable substratum or go out of the suitable substratum. The
model shows that the fate of the larvae tracked by the currents appear
s to be determined early in the pelagic phase by being trapped in low
current zones. Simulations allow the deduction of the advection losses
for different winds: the proportion of larvae reaching the adult habi
tat is 60 % at maximum for downwelling conditions and 15 % at minimum
for initial upwelling conditions. Our results indicate too that under
the most frequent wind conditions no mixing occurs between populations
of the 2 adult habitat zones which are 1.6 km apart from each other a
nd that no successful recruitment occurs from larvae coming from bays
located at the north of the considered coastal zone. Only combinations
of changing wind conditions could permit arrival of larvae from Pauli
lles Bay to Banyuls Bay. The interest of such individual-based models
consists not only in increasing our understanding of the link between
spatial and temporal dynamics of meroplanktonic populations but also i
n allowing us to explore the potential effects of habitat alteration o
n those populations.