The burial characteristics of organic carbon along the vicissitude of coastal oyster farming

Abstract Through biodeposition, oysters increase the flux of organic carbon (OC) that deposits and stabilizes on the seafloor and is potentially recorded in the sediment core. However, the linkage between oyster farming and OC burial has not received much attention. This study selected a typical oyster farm with approximately half a century of farming history in Sanggou Bay, China. The OC burial efficiency during the vicissitude of the farm was reconstructed by estimating OC biodeposition flux and OC burial flux. Additionally, microbial necromass was determined to indicate microbial activities. The results showed an increase in OC burial flux when farming became intensive, reaching an average of 91.60 ± 10.98 g m−2 yr−1 with a mean microbial necromass contribution of 30.51 ± 8.56% to the sediment OC. However, the burial efficiency was negatively correlated with OC biodeposition flux with an average of 30.17 ± 12.19%. The outcomes suggest that oyster farming has a strong OC burial capacity. Nevertheless, biodeposition flux from excessive farming triggers stronger microbial degradation of OC, reducing the ratio of OC from biodeposit to burial.