Restoration, dispersal and settlement of native European oyster (Ostrea edulis) in energetic tidal areas

We modelled the pelagic larval phase of native European oyster (Ostrea edulis) in the Solent. The Solent is a complex and tidally energetic environment on the south coast of the UK. Until recently it was the largest self-sustaining fishery of the native oyster in Europe. We developed a new larval settlement behavioural model that is the simplest plausible model which remains consistent with all available data and evidence on larval behaviour. We used a hydrodynamic sub-model, a Lagrangian advection sub-model, and an individual agent based model. The results demonstrate how isolated oyster assemblages can re-populate larger areas of historical inhabitance. We predict the most likely patterns of redistribution from refugia or from fisheries seeding. We show that settlement swimming behaviour is as equally important as passive hydrodynamic transport for larval survival and adult distribution and that settlement swimming behaviour has a profound impact on settlement patterns. The models show that managed broodstock refugia have the potential to seed much larger oyster beds in contrast to broad-scale seeding. Such refugia have the advantage of maintaining a locally high and mature population with potential for reef features and their associated biodiversity. We show that such refugia may be best placed in the tidally dynamic and exposed areas rather than on sheltered coastal sites as they have been in the past. Our model is insensitive to parameter variation and could be an effective and practical management tool in the face of a paucity of field data on larval distribution and behaviour.