Coastal ecosystem engineers and their impact on sediment dynamics: Eelgrass–bivalve interactions under wave exposure

Habitat forming ecosystem engineers play critical roles in structuring coastal seascapes. Many engineers, such as seagrasses and epifaunal bivalves, are known to have positive effects on sediment stability increase protection resilience. Others, bioturbating infaunal may instead destabilize sediment. However, despite the common co-occurrence of bivalves seascapes, little is their combined dynamics. Here, we used wave flumes compare dynamics monospecific multispecific treatments eelgrass, Zostera marina, associated (infaunal Limecola balthica, Cerastoderma edule, Magellana gigas) under a range exposures. Eelgrass reduced bedload erosion rates by 25–50%, with digital elevation models indicating that eelgrass affected micro-bathymetry decreasing surface roughness ripple sizes. Effects mobilization were species-specific; L. balthica 25%, C. edule increased 40%, while M. gigas had effect. Importantly, modified impacts bivalves: destabilizing vanished presence found additive stabilization potential for mutual anchoring. Such interspecific interactions likely relevant habitat patch emergence resilience extreme conditions. In light future climate scenarios where increasing storm frequency exposure threaten ecosystems, our results add mechanistic understanding between relevance management conservation.