Zhao Wei-Hua, Wang Hai-Jun, Wang Hong-Zhu, Liu Xue-Qin
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Ying Yong Sheng Tai Xue Bao. 2009 Jun;20(6):1452-8.
Mollusk biomass is usually expressed as wet mass with shell, but this expression fails to represent real biomass due to the high calcium carbonate content in shells. Tissue dry mass and ash free dry mass are relatively close to real biomass. However, the determination process of these two parameters is very complicated, and thus, it is necessary to establish simple and practical conversion methods for these two parameters. A total of six taxa of freshwater snails (Bellamya sp., Alocinma longicornis, Parafossarulus striatulus, Parafossarulus eximius, Semisulcospira cancellata, and Radix sp.) common in the Yangtze Basin were selected to explore the relations of their five shell dimension parameters, dry and wet mass with shells with their tissue dry mass and ash free dry mass. The regressions of the tissue dry mass and ash free dry mass with the five shell dimension parameters were all exponential (y = ax(b)). Among them, shell width and shell length were more precise (the average percentage error between observed and predicted value being 22.0% and 22.5%, respectively) than the other three parameters in the conversion of dry mass. Wet mass with shell could be directly converted to tissue dry mass and ash free dry mass, with an average percentage error of 21.7%. According to the essence of definition and the errors of conversion, ash free dry mass would be the optimum parameter to express snail biomass.
软体动物的生物量通常以带壳湿质量表示，但由于壳中碳酸钙含量高，这种表示方式无法代表实际生物量。组织干质量和无灰干质量相对更接近实际生物量。然而，这两个参数的测定过程非常复杂，因此，有必要为这两个参数建立简单实用的转换方法。选取长江流域常见的6种淡水螺（环棱螺属、长角涵螺、纹沼螺、中华沼螺、刻纹沼螺和萝卜螺属），探究其5个壳尺寸参数、带壳干质量和湿质量与组织干质量和无灰干质量之间的关系。组织干质量和无灰干质量与5个壳尺寸参数的回归均为指数关系（y = ax(b)）。其中，在干质量转换中，壳宽和壳长比其他三个参数更精确（观测值与预测值之间的平均百分比误差分别为22.0%和22.5%）。带壳湿质量可直接转换为组织干质量和无灰干质量，平均百分比误差为21.7%。根据定义本质和转换误差，无灰干质量将是表示螺生物量的最佳参数。
