Temporal variability in settlement of a coastal fish (Sillaginodes punctata) determined by low‐frequency hydrodynamics

Abstract

The temporal pattern of settlement of King George whiting (Sillaginodes punctata) in Port Phillip Bay, Australia, was compared with the temporal ingress of passive particles to the bay from adjacent coastal waters, predicted by a numerical hydrodynamic and dispersal model. The settlement data and the numerical model showed significantly correlated pulsing on an approximate 10–14‐d period. Pulsing was not obviously associated with individual oceanographic or climatic variables but was most likely caused by a combination of factors related to the passage of pressure systems and associated rotating winds that occur on a 7–14‐d cycle in this region. Such factors may include low‐frequency oscillations related to barometric pressure, reversals in longshore currents, and coastal trapped waves. Additionally, these processes would interact with the spring‐neap tidal cycle. The strong tidal currents in the region of settlement may overwhelm the behavioral responses of larvae and cause them to act as passive particles. High interannual variability in recruitment of S. punctata may relate to variation in the frequency and timing of hydrodynamic events that allow transport of larvae to juvenile habitats.