Abstract: By using sediment trap and closed respirator, a year-round in situ investigation was made on the bio-deposition rate, ammonia excretion rate, and phosphate excretion rate in the Ruditapes philippinarum bottom-cultured area of Zhuanghe coast. The three test rates of R. philippinarum all showed obvious seasonal variability, with the bio-deposition rate ranged in 0.15-1.47 g·ind^-1·d^-1 (annual average 0.61 g·ind^-1·d^-1),ammonia excretion rate ranged in 0.02-0.40 mg·ind^-1·d^-1(annual average 0.17 mg·ind^-1·d^-1), and phosphate excretion rate ranged in 0.01-0.39 mg·ind^-1·d^-1 (annual average 0.13 mg·ind^-1·d^-1). Based on these, it was estimated that the annual bio-deposit production by the bottom-cultured R. philippinarum in Zhuanghe coast could reach as high as 5.46×10⁷ t dry mass, amounting to 9.07×10⁶  t organic matter (OM), 1.00×10⁶  t organic carbon (OC), or 1.18×10⁵ t organic nitrogen (ON), and the annual NH₄⁺-N and PO₄^3--P productions were 1.49×10⁴ t and 1.15×10⁴ t, respectively. Our results suggested that for the large scale and high density bivalve culture in China coasts, the potential impacts of self-pollutants by filter-feeding bivalves on the environment should not be neglected.

Key words: Ruditapes philippinarum, bio-deposition, ammonia and phosphate excretion, self-pollution, Zhuanghe coast