A modelling study of environmental influences on bivalve settlement in The Wash, England

A previous statistical study (Young et al. 1996; Mar Ecol Frog Ser 143:121-129) has suggested that interannual variability in wind-driven transport of planktonic larvae may be responsible for fluctuations in fishery yields in The Wash, England. Predicted currents and depths from a validated, depth-integrated hydrodynamic model were used to drive an advection-diffusion model for the prediction of larval transport. Tides and the location of the larval release site had some effect on larval retention and settlement in The Wash, but the influence of winds was predicted to be considerably more important, causing up to a 3-fold greater variability in the predicted number of settled larvae. Differences in larval transport between years could produce as much as a 40-fold difference in the number of successfully settling larvae. Predictions of settlement for 7 yr strongly suggest that wind-induced larval transport contributes to interannual recruitment variation, although predicted settlement success was dependent upon spawning date. It is concluded that numerical modelling techniques have useful applications to the study of influences on larval settlement. However, predictions of settlement cannot be directly related to recruitment and future fishery yields without further consideration of post-settlement processes.