投喂量对中华卤虫解池种群产仔方式的影响

Effects of Feeding Rate on Reproductive Mode of Brine Shrimp Artemia sinica in Xiechi Lake

在NaCl质量浓度73g/L、25℃和光暗比12h∶12h条件下,将20日龄的中华卤虫成熟个体按每杯1雌1雄方式置于盛有约100mL高盐海水的玻璃杯中,用盐生杜氏藻按1.5×10~6、4×10~6、6×10~6、9×10~6个/杯4个投喂量培育30d,记录所产出的休眠卵和无节幼体数量,并测量休眠卵卵径、无节幼体体长和雌性亲体体长。试验结果表明,同时产休眠卵和幼体情形下的卤虫的产仔次数仅占总产仔次数的1.2%～2.9%。1.5×10~6、4×10~6、6×10~6个/杯3个试验组仅产卵的产仔次数占总产仔次数的30.4%～40%,仅产幼体的产仔次数占总产仔次数的57.5%～66.7%,而9×10~6个/杯试验组仅产卵及仅产幼体的百分比分别为61.3%和37.5%。4个试验组的单雌繁殖量分别为88.7、105.9、193、298.7个,单雌繁殖次数分别为2.7、2.9、3.9、4.7次,卵生后代比例分别为32.4%、31.1%、36.9%、66.2%。各试验组干卵径、卵生无节幼体体长和卵胎生无节幼体体长依次为1.5×10~6个/杯试验组<6×10~6个/杯试验组<4×10~6个/杯试验组<9×10~6个/杯试验组,且各试验组之间差异显著(P<0.05)。雌性亲体的最终体长随投喂量增加而显著增加(P<0.05)。研究结果表明,中华卤虫解池种群的雌体在饵料充足时偏卵生,在饵料匮乏时偏卵胎生;卤虫产仔方式受到投喂量的影响,但通过降低投喂量来改变产仔方式的做法在生产上是不经济的。

Brine shrimp(Artemia sinica)was fed fresh green alga Dunaliella salina under condition of a salinity of 73 g/L,25℃,photoperiod of 12 L∶12 D for 20 days until maturity and then moved to glass cups filled with 100 mL high salinity sea water in pair pattern of one female and one male per cup and fed the fresh green alga at a rate of 1.5×10 6 cells/cup,4×10 6 cells/cup,6×10 6 cells/cup,and 9×10 6 cells/cup for another 30 days.The number of produced cysts and nauplii were recorded,and the diameter of cysts,body length of nauplii and body length of parental females were measured.Three parturition modes were observed:①spawning cysts only;②spawning naupli only;③spawning both naupli and cysts,accounting for 1.2%-2.9%in the three modes.The mature brine shrimp fed the alga at feeding rates of 1.5×10 6 cells/cup,4×10 6 cells/cup and 6×10 6 cells/cup had the parturition times ratio of the 30.4%to 40%in the mode①to the total parturition times and 57.5%to 66.7%in the mode②,while the mature brine shrimp fed the alga at feeding rates of 9×10 6 cells/cup had the parturition times ratio of 61.3%in the mode①and 37.5%in the mode②.The total offspring number per female fed the four feeding rates was 88.7,105.9,193 and 298.7,the brood number per female were 2.7,2.9,3.9 and 4.7,and the ratio of oviparous offspring to total offspring were 32.4%,31.1%,36.9%and 66.2%.The mature brine shrimp fed the alga at feeding rates of various feeding rates had significantly different diameter of dry cysts and body length of oviparous nauppli and ovoviviparous nauppli(P<0.05),with the ascending order of mean values being expressed as treatment 1(1.5×10 6 cells/cup)<treatment 3(6×10 6 cells/cup)<treatment 2(4×10 6 cells/cup)<treatment 4(9×10 6 cells/cup).The means of final total lengths of parental females was increased significantly with the enhancement of feeding rate(P<0.05).The findings indicated that female brine shrimp from Xiechi Lake in tended to produce more oviparous offspring under sufficient food condition,and to produce more ovoviviparous offspring under insufficient food condition;feeding rate influenced the reproductive mode of females,but in practice it is not economic to change the reproductive mode by reducing food supply.