Influence of Ruditapes philippinarum aquaculture on benthic fluxes of biogenic elements in Jiaozhou bay

Nutrient excretion rates and the impact of Ruditapes philippinarum on benthic nutrient fluxes were measured by incubation experiments, and these results were used to assess the effect of R. philippinarum aquaculture on nutrient recycling in Jiaozhou bay. Our research indicates that the bioturbation of R. philippinarum would modify biogeochemical progresses in sediment, and restrain nutrients excreted by R. philippinarum releasing to overlying water. Only 37% DIN and 34% PO₄^3--P excreted by R. philippinarum were released to seawater across the sediment-water interface due to bioturbation of R. philippinarum. According to the reduction of nutrient exchange across the sediment-water interface by bioturbation, only 19% (N) and 17% (P) of biogenic elements fed by R. philippinarum can be recycled and returned to seawater, while the others would be removed from seawater in Jiaozhou Bay. The ratios of Si:N and Si:P of nutrients released from sediment to seawater with bioturbation of R. philippinarum were about 5:18 and 5:1, which were far less than Redfield ratios. Therefore, aquaculture of R. philippinarum should promote BSi biodeposition to sediment and reduce the nutrient ratios of Si:N and Si:P in seawater of Jiaozhou bay.