Short-Term Variations in the Chemical Properties and Microbial Diversity of Intertidal Sediments Using Oyster Shells in a Field Study

Nulcha Bay in Busan, South Korea, is famous for oyster farming. Because it is highly enclosed, it has a very low water exchange rate area, resulting in the accumulation of pollutants in the sediments. Furthermore, the disposal of oyster shell waste by oyster farm industries has been associated with serious environmental problems. In this study, we conducted field study on the restoration of intertidal sediments using heat-treated oyster shell powder (OSPW) and particles (OSPR). This research additionally studied changes in microbial community structure; this is the first report on changes in intertidal sediment microbial diversity using oyster shells. OSPW and OSPR efficiently decrease the levels of acid volatile sulfide (AVS), chemical oxygen demand (COD), total organic carbon (TOC), and heavy metals (arsenic, cadmium, chromium, copper, nickel, lead, mercury, zinc). The top three phyla observed based on 16S rRNA gene amplicon sequencing were Pseudomonadota, Thermodesulfobacteriota, and Chloroflexota. Furthermore, as a consequence of physicochemical changes in the sediment, we observed significant change in the relative abundance of Gammaproteobacteria, Desulfobulbus, and Anaerolineae. In conclusion, oyster shells are a promising material for controlling pollutants in the intertidal sediments and promoting diversity of bacterial population for sediment remediation.