Long-Term Oyster Recruitment and Growth are not Influenced by Substrate Type in China: Implications for Sustainable Oyster Reef Restoration

Successful and sustainable oyster reef restoration relies on suitable substrate material that is both readily available and encourages long-term recruitment and growth of oysters. China is increasing oyster reef restoration, however, little information is available to guide sustainable practices under local conditions and on ecologically relevant time scales. This study examines the effects of four substrate materials (oyster shell, clam shell, limestone, and clay brick) on community demographics for the Kumamoto oyster (Crassostrea sikamea) and associated macrofauna over a 3-y period in Xiangshan Bay, China. During the first 2 y, oyster and clam shell had similarly high recruitment and abundance of live oysters when compared with limestone and clay bricks. All substrate types, however, ended up with similar oyster abundances and size distributions after 3 y. Similar trends existed with regard to structural complexity (weight and volume) of substrate and any differences at the onset of the experiment were no longer apparent by the end. Abundance and community structure of associated macrofauna did not differ among the four substrate types regardless of time. These results indicate that different types of substrate material may be used for oyster reef restoration in China given projects have a scope longer than 2 y. These restored reefs can be expected to support viable and self-sustaining oyster populations with increased structural complexity and vibrant macrofaunal communities. Restoration practitioners using the Kumamoto oyster in China may use local materials as substrate for reefs and look forward to success where oyster recruitment is adequate and other factors such as predation and sedimentation are low