Variability in transport of fish eggs and larvae. III. Effects of hydrodynamics and larval behaviour on recruitment in plaice

摘要

Transport of plaice eggs and larvae in the southern North Sea was modelled using a finite-volume advection-dispersion model with high spatial and temporal resolution. Hydrodynamic forcing was based on actual river discharge and meteorological data for a 7 mo period in the winter and spring of 1989 and 1996 to 2003. Egg and larval development was linked to temperature and each developmental stage had its own physical and behavioural properties. Two hypotheses on transport mechanisms in the late larval stages were compared: passive drift versus selective tidal stream transport (triggered by environmental cues). Modelled larval stage durations closely corresponded to empirical estimates based on otolith daily ring counts. Close correspondence was also observed between model results and survey data on settlement in the western Wadden Sea, especially for the abundance of the strong 1996 year-class and the early settlement of the 2002 year-class. Transport patterns and the proportion of larvae reaching inshore nurseries varied substantially between years. Recruitment was negatively correlated with the distance over which eggs and larvae were transported, probably because of a breakdown in connectivity between spawning and nursery areas with increased transport rates. In conclusion, meteorologically driven variability in the hydrodynamics of the southern North Sea greatly affects the transport patterns of plaice eggs and larvae and may play an important role in determining recruitment variability and spatial connectivity.