Recently, the scientific research team of the Key Laboratory of Marine Ecosystem and Biogeochemistry of the SIO took the raft-cultured oysters in Xiangshan Port as the research object, and revealed the mechanism of oyster biodeposition promoting the accumulation of trace metal elements into the substrate after four seasons of field research. The relevant achievements were published in the Journal of Hazardous Materials, the international top 

Filter-feeding shellfish can ingest a large number of suspended particles in the water, absorb nutrients through the digestive system, then discharge them out of the body in the form of feces or “fake feces” and deposit to the seabed, which is called biodeposition. Biodeposition will accelerate the sedimentation of particles in water body and transport a large number of matters to the seabed. At present, researches at home and abroad mainly focus on the impact of shellfish biodeposition on the biogeochemical cycle of carbon, nitrogen, phosphorus, silicon and other nutrient elements. Limited by research means, little attention has been paid to trace metal elements, which can usually be used as characteristic indicators in different research fields.

The study showed that the biodeposition rate of cultured oysters is higher in summer and autumn, and the lowest in spring. By comparing the contents of oyster biological sediments, settleable particles, surface sediments and dissolved trace metals in different water layers, the scientific research team found that the biodeposition process of oysters accelerated the transport of trace elements in the upper water body to the bottom layer, resulting in the relative enrichment of trace elements in the bottom sediment, and proposed the biogeochemical cycle mechanism of filter-feeding shellfish driving trace metals to return from the aqueous phase to the sedimentary phase, proving that the biodeposition of cultured oysters can regulate the biogeochemical process of trace metals in the bay ecosystem, and accelerate the migration of suspended particulate trace elements in the water to the bottom. The research results will help to fully understand the impact of high-density shellfish culture on the bay environment, offer scientific basis for promoting the safe and healthy development of shellfish culture industry, and also provide a new criterion for the coordinated development of regional industrial agglomeration and shellfish culture.

A research paper entitled “Influence of biodeposition by suspended cultured oyster on the distributions of trace elements in multiple media in a semi-enclosed bay of China” was published in terms of this research achievement, with Associate Researcher Liu Qiang as the first author, and Senior Engineer Shou Lu and Researcher Zeng Jiangning as the corresponding authors.