pH和盐度对大型溞心率和摄食行为的影响

Effects of pH and salinity on heart rate and feeding behavior of Daphnia magna

摘要:

以1日龄和12日龄大龄溞（Daphnia magna）为研究对象，研究了8个pH（4~11）和8个盐度（1~8）水平对其心率和摄食行为的影响。两种生长期大型溞对pH和盐度值变化的响应都表现出“低促高抑”的趋势，对碱性水体的适应性大于酸性水体。幼龄溞和大龄溞的最适pH范围分别为6~8和7~9，最适盐度分别为2和3，幼龄溞对pH和盐度变化较大龄溞敏感，对外界不良环境的适应性低于大龄溞。幼龄溞在pH为10、盐度为5时心率分别为372.1±15.1和365.3±10.2，与对照组相比差异极显著（P<0.01），其心率高于大龄溞，但适应范围较大龄溞窄。在pH为8时，幼龄溞的滤水率和摄食率都达到最大，与对照组相比，滤水率上升不显著（P>0.05），摄食率显著提高（P<0.05），大龄溞在pH为9时规律相同。在盐度为2时，幼龄溞的滤水率和摄食率都达到最大，与对照组相比，滤水率显著增大（P<0.05），摄食率增加极显著（P<0.01），大龄溞在盐度为3时有同样规律。研究表明：不同生长期大型溞的最适pH和盐度不同，应合理调整pH和盐度，促进产量最大化。

Abstract:

The heart rate and feeding behavior of one-day and 12-day-old Daphnia magna were studied at eight pH values (4-11) and eight salinities (1-8). The effects of pH and salinity on two ages of Daphnia magna exhibited the similar tendency——to promote at low and to suppress at high. The adaptability to alkaline water is greater than that to acidic water. The optimum requirement of young and old Daphnia magna were 6-8 and 7-9 for pH, 2 and 3 for salinity, respectively. The metabolism of young individuals was higher than the old, and the young were more sensitive to pH and salinity change, but less adaptable to adverse external environment. The heart rate of the young Daphnia at pH 10 and at salinity 5 was (372.1±15.1) and (365.3±10.2) with highly significant difference from the control (P<0.01), higher than the old but narrower adaptability. At pH 8, the filtration rate and feeding rate of the young Daphnia reached maximum and the feeding rate was significantly higher than the control (P<0.05), just as the regularity of the old at pH 9. At the salinity of 2, the filtration rate and feeding rate of young population were the highest, both significantly higher than the control, similar to the old at the salinity of 3. It can be concluded that different ages of Daphnia magna have different optimum pH and salinity, so pH and salinity should be reasonably adjusted to maximize the production.