生活周期毒性试验动物─—方形网纹溞的生物学

BIOLOGY OF CERIODAPHNIA QUADRANGULA,(O.F.MULLER),AN EXPERIMENTAL ANIMAL FOR LIFE-CYCLE TOXICITY TEST

在实验室条件下研究方形网纹的生物学。试验时水温２５±１℃，饲以斜生栅藻。初生幼体平均体长０．４０ｍｍ，第１成龄０．９６ｍｍ，最大体长可达１．４５ｍｍ，体长增长（１＿ｔ，单位ｍｍ）与年龄（ｔ，ｄ）的关系可以表达为１＿ｔ＝１．４３－ｅ￣（－０．２６８ｔ），平均寿命２２．７３（１７．１０－２５．００）ｄ，其中包括３个幼龄和１３个成龄。在３．９１ｄ达到性成熟。７ｄ内生殖３胎，产仔４０（１９－４７）个。一生生殖２２２．０个幼体，平均每胎１８．５（４．８－２３．６）个。生殖量最大出现在第６成龄。这时的年龄１１．０５ｄ，体长１３７５ｍｍ。从初始１０个个体的种群计算，种群生长曲线呈Ｌｏｇｉｓｔｉｃ型，可以如下表达式中ｙ表示总个体数，ｔ表示时间（ｄ）。内禀增长能力（ｒ＿ｍ）为０．５４０／个／ｄ，净增殖率（Ｒ＿ｏ）１４７．３６０／世代，世代平均周期（Ｔ）９．２４６ｄ，周限速率（λ）１．７１６／个／ｄ。

Biology of parthenogenetic females of Ceriodaphnia quadrangula(O.F.Muller)wasstudied under laboratory conditions at 25±1℃,Scenedesmus obliquus(Turp.)Kutz wasused as food for the animals during the experiments. The mean body -length of neonatesof C. quadrangula was 0.40mm and that of the first adult instar 0.96mm,A maximumlength of 1.45mm was attained.The growth in body─length(1_t,in mm)in relation to age(t,in day) can be described asl_t=1、43 -e￣(-0.268t)The mean longevity was found to be 22.73(17.10─25.00)days for 3 preadult and 13adult instars.Sexual maturity was reached in 3.91 days.40(19─47) young from 3 broods wereobtained in 7 days.The mean number of young per brood was 18.5(4.8─23.6).The totaloffspring production by one adult reached 222.1 during its life─span. The maximum re-production period occurred during the 6th adult instar. At this age,the animals were11.05 days old,and had a body length of 1.375mm.In a population originated from 10 individuals,the population growth curve of C.quadrangula was shown to be logistic and may be expressed asin which y denotes total number of individuals and t, days.The innate capacity for increase(r_m)was 0.540 per female per day,the net repro-duction rate(R_o)was 147.360 per generation, the mean length of a generation(T)was9.246 days, and the finite rate ofincrease(λ)was 1.716 per female per day.