水体Ca^(2+)对三角帆蚌珍珠质沉积的影响

THE EFFECTS OF Ca^(2+) CONCENTRATION ON THE DEPOSITION OF NACRE IN HYRIOPSIS CUMINGII

为研究不同水体Ca^(2+)浓度(10—80 mg/L)下三角帆蚌生长和珍珠质沉积量和晶体结构的变化,采用鱼蚌混养的养殖模式养殖10周。结果表明,1龄幼蚌生长的适宜Ca^(2+)浓度为40 mg/L,2龄未植片三角帆蚌生长的适宜Ca^(2+)浓度为40—70 mg/L,2龄植片三角帆蚌珍珠沉积的适宜Ca^(2+)浓度为40 mg/L。拉曼光谱分析和珍珠层小片的扫描电镜观察结果表明,适宜Ca^(2+)浓度影响三角帆蚌珍珠质沉积可能是通过促进外套膜组织有机基质分泌从而调节Ca CO_3晶体形成和生长实现的。研究结果提示,在三角帆蚌生长快速季节,养殖水体中添加一定的钙源如生石灰等将有利于蚌体和珍珠的生长。同时研究结果也为加快珍珠培育,提高珍珠品质提供理论依据和实践操纵手段。

Calcium concentration has crucial effects on the growth and nacre deposition of the freshwater pearl mussel Hyriopsis cumingii. However, the suitable Ca^2＋ concentration for the mussel culture and nacre deposition has been controversial. In this paper, we investigated how the Ca〉 concentration regulated the growth of Hyriopsis cumingii, the nacre deposition, and the nacre crystal structure. Pearl mussels were co-cultured with fish under different Ca^2＋ concentrations from 10 to 80 mg/L. The results showed that 1-year-old mussels grew fastest under the Ca^2＋ concentration of 40 mg/L. The suitable Ca^2＋ concentration range for the growth of 2-year-old non-implanted mussels were 40 mg/L to 70 mg/L. The suitable Ca^2＋ concentration for the pearl deposition of 2-year-old implanted mussels was 40 mg/L. Using Raman spectra and scanning electron microscope we showed that Ca^2＋ at the suitable concentration facilitated the nacre deposition of pearl mussels through promoting the secretion of organic matrix and the crystallization and growth of CaCO3. Our results implied that adding exogenous calcium, such as quicklime, into the water could improve the growth of the mussels and pearls. This method is potentially a new tool to accelerate the pearl cultivation and to improve the pearl quality.