Metamorphosis and settlement

At the end of their free swimming veliger stage (2-4 weeks for the targeted species in REPROSEED), larvae prepare to undergo metamorphosis, during which major morphological changes occur. Significant losses can often happen during this phase in hatcheries. Once metamorphosed - or during the process of metamorphosis - post-larvae undergo settlement or fixation. Metamorphosis inducers have been developed to assist with control of the timing of metamorphosis in oysters, and such products can be useful for dissociating metamorphosis from settlement. At a molecular level, the key genes involved in this transitional phase from pelagic to sedentary life are, as yet, unknown. Populations of bivalve larvae do not settle uniformly at the same time and unfortunately seed that fail to attach can be lost from system. In oysters, some chemical inducers can be used to improve uniformity of settlement.

REPROSEED will use molecular, phenotypic and behavioural approaches to study the effects of chemical and bacterial inducers on control of metamorphosis and to optimize settlement for species with motile spat (scallops, clams and mussels).