Patterns of oyster recruitment and habitat provision across tidal elevation gradients are dependent on predator mitigation methods
Esquivel-Muelbert, J.; Lanham, B.S.; Didderen, K.; van der Heide, T.; Bishop, M.J. (2025). Patterns of oyster recruitment and habitat provision across tidal elevation gradients are dependent on predator mitigation methods. J. Appl. Ecol. 62(3): 726-738. https://dx.doi.org/10.1111/1365-2664.14866
In: Journal of Applied Ecology. British Ecological Society: Oxford. ISSN 0021-8901; e-ISSN 1365-2664, more
For restoration projects conducted in environments with strong predation, effective predator mitigation can be key to the successful recruitment of habitat-forming species, and the development of associated ecological communities. Predator mitigation may involve exclusion through caging, or the provision of protective spaces through complex habitat mimics. The relative efficacy of the two approaches may vary across environmental gradients, according to predation and environmental stress.
To inform the most effective predator mitigation methods for oyster reef restoration, we compared oyster recruitment and associated community development between uncaged concrete blocks, caged concrete blocks and biodegradable complex habitat mimics (BESE), across three tidal elevations and three sites in eastern Australia.
After 1 year, oyster and associated invertebrate recruitment to uncaged concrete was low at all sites and tidal elevations. Whereas BESE supported greater invertebrate abundance and richness than caged concrete blocks at all elevations, the relative performance of the two predator mitigation methods in facilitating oyster recruitment was spatially variable. In the subtidal, BESE were less effective at excluding small-bodied mesopredatory fishes than caged concrete units and supported less oyster recruitment. In the intertidal, where exposure to mesopredatory fish is less due to emersion at low tide, there was greater recruitment to BESE than to caged concrete.
Synthesis and applications. The effectiveness of predator mitigation methods used in oyster reef restoration can vary across small-scale gradients. Understanding the strength of predator–prey interactions at local scales, and the identity of key predators, is crucial for designing restoration methods that allow colonisation of target species and exclude key predators.
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