栉孔扇贝生物沉积作用的研究

Biodeposition by scallop Chlamys farreri

2001年3～9月,在自然养殖状态下对栉孔扇贝(Chlamysfarreri)的生物沉积及其对物质输运的影响进行研究。结果表明,栉孔扇贝能加速海洋中颗粒物质的沉积,生物沉积率分别为:小个体(壳长30～40mm)72.31～109.85mg·ind-1·day-1、中等个体(壳长50～60mm)103.49～207.77mg·ind-1·day-1和大个体(壳长60～70mm)120.05～237.65mg·ind-1·day-1。栉孔扇贝的生物沉积与其壳长呈正相关线性关系,与其干组织重呈正相关的指数关系,而单位重量的生物沉积则与壳长和干组织重分别为负相关的线性和幂指数关系。海水温度和环境中饵料数量是影响栉孔扇贝的生物沉积的重要因子。

Studies on marine bivalves have demonstrated that suspension-feeding bivalves scan influence the function of ecosystems to a great extent. In dense populations, bivalves can dominate total ecosystem metabolism, nutrient cycling, and grazing of primary producers. Farrer' scallop (Chlamys farreri Jones et Preston) is a promising species, which has been widely cultured in the neritic waters in China, particularly in the Bohai Sea and the Yellow Sea. Scallop farming has been bringing not only great economic benefit, but also great burden for the neritic ecosystem due to filtering food and releasing metabolic production. To estimate the effects on neritic ecosystem of scallop cultivation, the experiments were monthly conducted near Xiao Qingdao Island from March to September 2001. The biodeposition by Farrer' scallop and the effects of biodeposition on material flux were measured under natural cultivation conditions. THe Farrer' scallops, with body sizes of 30-76 mm shell height and 0.3-3.0 g dry tissue weight, were collected from the Maidao scallop farm south of Qingdao. The scallop samples were divided into three groups, according to their body size, they were small size (30-40 mm), middle size (50-60 mm) and big size (60-70 mm). Each group was arranged five parallel experiments. The results show that the biodeposition rates were 72.31-109.85 mg·ind^(-1)·day^(-1), 103.49-207.77 mg·ind^(-1)·day^(-1) and 120.05-237.65 mg·ind^(-1)·day^(-1) for small size, middle size and big size of Farrer' scallops, respectively. The amount of biodeposit was correlated positively with the shell length and weight, but the per gram body weight biodeposit negatively. With the water temperature rising from March to September, the chlorophyll a concentration in sea water increased from 1.8 μg·L^(-1) to 7.4 μg·L^(-1) and reached the peak values at 18.2 ℃ in June, then went down until September. The same tendency appeared in the contents of TPM, POM, POC and PON, but the fluactuation was relatively great. As a consequence, the biodeposition by each group scallops increased from 72.3 mg·ind^(-1)·day^(-1) to 109.9 mg·ind^(-1)·day^(-1), 103.5 mg·ind^(-1)·day^(-1) to 207.8 mg·ind^(-1)·day^(-1) and 120.1 mg·ind^(-1)·day^(-1) to 237.7 mg·ind^(-1)·day^(-1), then decreased to 79.0 mg·ind^(-1)·day^(-1), 174.2 mg·ind^(-1)·day^(-1) and 178.8 mg·ind^(-1)·day^(-1) in August, respectively. Those demonstrated that water temperature and food concentration were important factors to affect biodeposition of Farrer' scallops.