水质酸化对双棘臂尾轮虫种群动态的影响

Effects of Water Acidification on the Dynamics of Population Growth of Brachionus bidentata

用人工酸化的东湖水为培养液对双棘臂尾轮虫进行室内单个体培养研究．结果表明，与用未酸化的东湖水培养结果相比，轮虫非混交雌体的平均产卵量在 ｐＨ６． ５、５ ５和 ４． ５时增加，而在 ｐＨ３．５时减少．在 ｐＨ５．５和 ３．５时轮虫种群的内禀增长率增大，种群中无混交雌体出现；而在ｐＨ６．５和４．５时内禀增长率减小，混交雌体百分率增大．在本实验ｐＨ范围内，双棘臂尾轮虫具有耐酸性．

A study was carried to investigate the effects of precipitation-acidified water of Donghu Lake on the survival and reproduction of Brachionus bidentata under the condition of individual culture. The experiment was conducted at 28t in a photoperial (L: D = 18: 6) with light intensity about 500 lx. The rotifers were fed with Chlorella Pyronoidosa at a density of 6. 0 × 10_6cells mL^(-1) and the mediums were exchanged once twelve hours. The results show that when the rotifers were cultured in unacidified water (pH8. 4) of Donghu lake, the percentage of mictic females and the mean number of amictic eggs were 8. 33 % and 13. 909, respectively; The intrinsic rate of the population was 0. 076015 h^(-1). Compared with the above results, when the media was acidified to PH 6. 5, 5. 5 or 4. 5, the numbers of amictic eggs increased to 18. 778, 18. 167 and 15. 5 md., respectively; but decreased to 12. 083 md. at pH 3. 5. The intrinsic rates of the populations at PH 5. 5 and 3. 5 increased to 0. 08901 and 0. 079684 h^(-l), and no mictic females appeared, respectively. At pH 6. 5 and 4. 5, the intrinsic rates decreased to 0. 069258 and 0. 07354 h^(-1), but the percentages of mictic females increased to 25 % and 16. 67 %, respectively. Between pH 6. 5 and pH 3. 5, Brachionus bidentata was acid tolerant.