The work carried out so far highlights Poole Harbour as being an anomaly in the apparent steady progressive development of Pacific oyster populations around the coast, in that there is an obvious source of larvae but little successful settlement. The mechanisms which are âdampening downâ expected settlement appear to include at least one physical factor but it is likely that this is moderated by biological factors such as competition for settlement space and predation. Further work is required to establish which biological factors may be modifying recruitment success and whether recruitment is moderated during the larval stage or post metamorphosis. if the dominant controlling factor(s) act before oyster settlement it is most likely water temperature that controls the naturalised population, however top-down control by predators could be significant if oysters are surviving metamorphosis.
