镜湖长三肢轮虫的有性生殖

2004年5—11月,对芜湖市镜湖大、小湖区水体中长三肢轮虫(Filinia longiseta)的有性生殖及其与种群密度、水温、水体透明度、水体叶绿素a含量和轮虫总密度等环境因子间的关系进行了研究.结果表明:当水温低于22℃或水体透明度大于一定值(小湖区SD>95cm,大湖区SD>100cm)时,长三肢轮虫不进行有性生殖;而当其本身的种群密度达到一定值(小湖区种群密度>122ind·L-1,大湖区种群密度>113ind·L-1)时才进行有性生殖.长三肢轮虫的混交雌体密度仅与其本身的种群密度以及水体中轮虫总密度之间呈正相关关系(P<0·01),而与水温、叶绿素a含量、水体透明度之间均无明显的相关关系;长三肢轮虫种群的混交率和受精率与水温、水体透明度、叶绿素a含量、轮虫总密度和长三肢轮虫种群密度之间也无明显的相关性.长三肢轮虫的有性生殖发生在种群增长的早期阶段,混交雌体以间断的、多循环的方式产生;最大混交率与最大种群密度同时出现,但最大受精率出现在种群即将消失时.

Sexual reproduction of Filinia longiseta in Jinghu Lake of Wuhu City

From May to November 2004, the sexual reproduction of Filinia longiseta in two areas of Jinghu Lake was studied, with its relations to the population density of F. longiseta and to the water temperature, Chl-a concentration, Secchi's disc reading, and total density of rotifers examined. The results showed that no mictic F. longiseta females were detected till the water temperature was up to 22 degrees C or the Secchi's disc reading was <95 cm in small area and <100 cm in large area. The sexual reproduction of F. longiseta occurred when its population density was > 122 ind . L(-1) and >113 ind . L(-1) in small and large areas, respectively. The density of mictic F. longiseta females was positively correlated to the population density of F. longiseta and the total density of rotifers (P <0. 01), but no significant relationships were observed between the mictic F. longiseta females density and the water temperature, Chl-a concentration and Secchi's disc reading. All the test affecting, factors had no significant effects on F. longiseta mictic and fertilization rates. The sexual reproduction of F. longiseta occurred in the early phase of population growth cycle, and the mictic F. longiseta females were produced in the patterns of punctuation and multi cycles. The maximal mictic rate occurred with the occurrence of maximal population density, while the maximal fertilization rate occurred by the end of population growth cycle.