pH值对萼花臂尾轮虫种群增长及繁殖的影响

Influence of medium pH on population growth and reproduction of Brachionus calyciflorus.

采用种群积累培养法，实验观察了 ｐＨ在３．５～１１．５之间（间隔 １）萼花臂尾轮虫 （Ｂｒａｃｈｉｏｎｕｓ ｃａｌｙｃｉｆｌｏｒｕｓ）种群的增长及繁殖．结果表明，该轮虫种群在ＰＨ６．５～８．５之间增 长较快， ８． ５时增长最快，即瞬时增长率 ｒ和种群密度较大和最大； ｐＨ在 ３． ５～４． ５和 ９． ５ ～１０． ５之间，种群为负增长，即 ｒ为负值； ｐＨ在 ５． ５～９． ５之间种群为正增长，即正为正 值．该轮虫存活的ｐＨ上限为１１．５，下限为３．５．在种群增长最适ｐＨ（８．５）条件下，该轮虫 的繁殖最快，即绝对带卵量最高（１３２个·ｍｌ－１）；ｐＨ在９．５时，其相对带卵量最高．为其它 ｐＨ值条件下的２～４倍．本研究结果可为淡水轮虫的大批量培养提供可靠的ｐＨ值技术指 标．

With the method of population accumulation culture, the population growth and reproduction of rotifer(Brachionus calyciflorus ) were observed in pH 3. 5 ~ 11. 5 media with an increment of 1 pH unit. The results show that rotifer population grows faster at pH 6. 5 ~ 8. 5 and fastest at pH 8.5, indicating that in this pH range, the instantaneous rate(r) is fast and the density is the maximum. At pH 5. 5~9. 5. the r value is positive. but at pH 3. 5~4. 5 and 9. 5~ 10. 5, it is negative, i. e.. the population shows a negative growth. Rotifer can survive at pH 3. 5 ~ 11. 5, but the optimum pH for population growth is 8. 5. where the rotifer shows a maximum reproductive sped. and the absolute egg density is the highest (132 cells' ml-1 ). The relative egg density is the highest at pH 9. 5, 2~4 times larger than that al other pH values.