In order to evaluate the effect of the dominant buried clam on pelagic-benthic coupling in an estuary ecosystem, the field experiments on biodeposition, respiration and excretion of Meretrix meretrix were conducted from July 2010 to April 2011 in the Shuangtaizi Estuary, Bohai Sea of P. R. China. Different sizes of clams, namely 2-yr old clams ((36.36 ± 0.23) mm, SH) and 3-yr old clams ((46.60 ± 0.23) mm, SH) were collected respectively. The results showed that there were significant seasonal changes on biodeposition, oxygen consumption and excretion rates of the hard clams among four seasons, with the maximum rates in summer and minimum rates in winter. The seasonal variation of biodeposition rates for 2 and 3-year-old M. meretrix were 0.02-0.30 g^-1 ind^-1 d^-1 and 0.06-0.60 g^-1 ind^-1 d^-1, respectively, among seasons. The hard clams consumed considerable amount of oxygen, ranging from 0.45-16.64 mg^-1 ind^-1 d^-1 and 1.03- 30.51 mg^-1 ind^-1 d^-1 for 2 and 3-year-old species, respectively. Ammonium excretion rates respectively ranged from 0.001-0.14 mg^-1 ind^-1 d^-1 and 0.002-0.28 mg^-1 ind^-1 d^-1 for 2 and 3-year-old clams. The hard clam M. meretrix released 0.002-0.069 mg^-1 ind^-1 d^-1 and 0.003-0.16 mg^-1 ind^-1 d^-1 PO₄^3--P in the 2 and 3-year-old clams. All the physiological rates of the tested clams at the same season showed a similar tendency of 2-year-old < 3-year-old among the four seasons. One-way ANOVA showed that there were significant effects of seasonality, clam age and their interactions on biodeposition, respiration and excretion rates of the clam. A density of 0.67ind/m² of and a biomass of 2.4 g/m² were previously observed in spring, summer and autumn in twelve sampling sites of the Shuangtaizi Estuary. Based on the above data, it is estimated that the hard clams may produce 1.43 tons of NH₄⁺-N, 0.93 tons of PO₄^3--P and discharge as much as 5321.90 tons of deposit to the estuary waterbody, and consume 221.59 tons of O₂ annually. Our study indicates that M. meretrix populations greatly enhanced material exchange fluxes across the water-sediment interface through its biodeposition, respiration and excretion process, and plays an important role in pelagic-benthic coupling in Shuangtaizi Estuary.