Settlement of Ostrea edulis is determined by the availability of hard substrata rather than by its nature: Implications for stock recovery and restoration of the European oyster

Abstract

1. Since the collapse of the Ostrea edulis stock in the mid-1800s the oyster has struggled to re-establish itself in self-sustaining assemblages in Europe. 2.It is now widely recognized that O. edulis is an integral component of a healthy biologically functional benthic environment and, as such, the restoration of wild stocks has become a matter of urgency. 3.A major limiting factor in O. edulis stock recovery is the availability of suitable substrate material for oyster larvae settlement.4. This research re-examined the larval settlement potential of several naturally occurring in-situ shell materials (e.g. Mytilus edulis, Modiolus modiolus, O. edulis), with the aim of determining which shell material is the most appropriate for large-scale restoration projects. 5.A positive correlation between available shell material and settlement was determined, and analysis using PERMANOVA did not identify an attachment preference by O. edulis to any particular shell type.6. The findings suggest that if restoration efforts were coordinated with applied hydrodynamic and habitat suitability modelling, in conjunction with naturally occurring shell substrate concentrations, a cost-effective recovery for O. edulis assemblages in the wild could be achieved.

Wild gregarious settlements of Ostrea edulis in a semi‐enclosed sea lough: a case study for unassisted restoration

“…A significant higher density of O. edulis attachments were discovered at Cunningburn post‐2014 when compared to other sites. In contrast to the findings of Smyth et al () the survey showed that, when available, at Strangford Lough O. edulis pediveligers' attachment material of choice was the living edge of a live oyster. Researchers have emphasized this fact previously in relation to larval settlements within Ostrediae spat (Breitburg et al ; Tamburri et al ).…”

“…The availability of shell, as opposed to shell type, has been shown to be influential in settlement success (Smyth et al ). A significant higher density of O. edulis attachments were discovered at Cunningburn post‐2014 when compared to other sites.…”

“…). Kircubbin, Pig Island, and Ringhaddy were considered low‐density O. edulis sites in comparison with a predominantly mud and shell fragment substrate (Kennedy & Roberts ; Smyth et al ). All sites were intertidal as extensive dive surveys in the region between 2008 and 2011 had shown the subtidal substrate to consist of heavy mud absent of a shell mix and therefore unsuitable for O. edulis larval settlement (Roberts et al ).…”

“…As the majority of historic European oyster sites are in a poor state of conservational health, any locations which retain a resident self‐sustaining population could offer an important insight into environmental parameters which could be replicated to promote recovery (Carlucci et al ). Presently, numerous European countries are attempting to address the dwindling wild stocks through the augmentation of cultured or translocated oysters (Smyth et al ; Pogoda et al ).…”

First molecular record of the alien species Pacific oyster (Crassostrea gigas, Thunberg 1793) in the Marmara Sea, Turkey

“…They feed on microalgae and they either live freely or by fixing themselves with their right shells in coastal waters (Tebble, 1966). In economic and food quality terms, O. edulis is a very valuable species in the markets (Yildiz et al, 2011;Acarli et al, 2015;Smyth et al, 2018). Unlike O. edulis, C. gigas is not a native species in Mediterranean region.…”