Can relic shells be an effective settlement substrate for oyster reef restoration?

Abstract

Acute storms (e.g. hurricanes) are major stressors to eastern oysters (Crassostrea virginica) through burying oysters and settlement substrate. Subsequently, managers use many restoration efforts, of which one approach is bag‐less dredging. This resurfaces relic shells as settlement substrate; however, buried shells turn black in anoxic sediments potentially influencing spat settlement. This study compared three shell types: sun‐cured white shell utilized in oyster reef restoration and two representative black shell types for bag‐less dredging. Settlement was significantly higher on sun‐cured white shell suggesting that restoration activities resurfacing black shells may not provide suitable substrate and alternative methods of providing substrate should be prioritized.