Avoiding offshore transport of competent larvae during upwelling events: the case of the gastropod Concholepas concholepas in Central Chile.
Concholepas concholepas
Castilla, J. C., Leiva, G. E, Narvaez, D, Navarrete, S. A, Pacheco, R, Palma, A. T, Poulin, E.
https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2002.47.4.1248
La costa de Chile central se caracteriza por la ocurrencia de surgencias costeras durante las temporadas de primavera y verano australes, lo que probablemente tenga consecuencias importantes para el transporte a través de la plataforma de estadios larvarios de muchas especies. Se realizaron tres cruceros frente a la localidad de El Quisco durante períodos de vientos favorables a las surgencias para determinar la distribución superficial de larvas epineustónicas competentes del gasterópodo Concholepas concholepas durante tales eventos. Contrariamente a las predicciones del modelo tradicional, donde las larvas de tipo neustónico son transportadas mar adentro en tales condiciones, las larvas competentes de esta especie se encontraron exclusivamente en el área entre la costa y el frente de surgencia. Se realizaron dos cruceros adicionales durante períodos de calma para determinar la variación diaria en la distribución vertical de larvas competentes de C. concholepas. La ausencia de larvas competentes en la superficie durante las primeras horas de la noche sugiere una migración vertical inversa. Por lo tanto, la retención de larvas competentes de C. concholepas en las aguas afloradas podría ser el resultado de la interacción entre su migración vertical diel inversa y la dinámica típica de surgencia de dos capas.
The coast of central Chile is characterized by the occurrence of coastal upwelling during the austral spring and summer seasons, which probably has important consequences for the cross-shelf transport of larval stages of many species. Three cruises were conducted off the locality of El Quisco during upwelling-favorable wind periods to determine the surface distribution of epineustonic competent larvae of the gastropod Concholepas concholepas during such events. Contrary to the predictions of a traditional model, where neustonic-type larvae are transported offshore under such conditions, competent larvae of this species were exclusively found in the area between the shore and the upwelling front. Two additional cruises were conducted during calm periods to determine diel variation in the vertical distribution of C. concholepas competent larvae. The absence of competent larvae at the surface during early night hours suggests a reverse vertical migration. Thus, the retention of C. concholepas competent larvae in the upwelled waters could be the result of the interaction between their reverse diel vertical migration and the typical two-layer upwelling dynamics.
