温度和食物浓度对老年低额溞生长与生殖的影响

EFFECT OF TEMPERATURE AND FOOD CONCENTRATION ON THE GROWTH AND REPRODUCTION OF SIMOCEPHALUS VETULUS

  • 摘要: 在20℃和25℃培养温度下研究了3种食物浓度对老年低额(Simocephalus vetulusOF Müller)生长与生殖的影响。结果表明:老年低额有4个幼龄(在20℃、低食物浓度下有5个)和10-13个成龄。成龄的龄期明显高于幼龄,第一成龄的发育时间一般最长。在相同温度下,老年低额的首次怀卵所需时间及各龄期一般随食物浓度的增加而缩短,而各龄的平均体长及其生殖量则呈相反的趋势。在相同的食物条件下,25℃老年低额在生长后期的平均体长明显高于20℃,而各龄期却小于20℃。最大体长是2.82mm,出现在25℃、高食物浓度下的第16龄。老年低额的平均最大生殖量和最大内禀增长率分别为144个和0.41/d,均出现在25℃和高食物浓度下。统计分析显示老年低额的生殖量与体长之间存在显著的相关性。老年低额的食物浓度域值小于1×104cells/mL(Scenedesmus obliquus)。作者探讨了老年低额在渔业生产中作为活体饵料养殖对象的可能性。

     

    Abstract: In this study, body length, duration of instar, lifespan, egg production, and survival rate of Simocephalus vetulus were investigated under three food concentrations and two temperatures(20℃and 25℃)in the laboratory.S. vetulus was from the coal collapsed water in Huaibei City. The collected animals were cultured in an incubator at 25 ℃.Females containing embryos were isolated in 50 mL beakers and acclimated to the experimental temperatures. The offspring from these females were isolated and reared under the same conditions until the juveniles were released. Then, these juveniles were used for the experiment. Three food concentrations(2×105, 1×105 and 1×104cellsm L-1) ofScenedesmus obliquus were used. The culture medium was tap water that was exposed, and was refreshed daily. All experiments were carried out under a constant light regime of 12 hlight: 12 h dark.The results showed: S. vetulus had four juvenile instars, except there were five at 20℃ and under low food concentration,and 10-13 adult instars. The adult instar durations of S.vetulus were higher than those of juvenile instars, and the development time of the first adult instar was generally the longest. The first pregnant time and each duration of instar shortened with the increase of food concentration at same temperature, while average body length and brood size showed a reverse trend. At 20℃,the highest lifespan under high and middle food level was longer than at low food level, while mean lifespan was shorter than at low food level. At 25℃, both mean and highest lifespan under high and middle food concentrations were longer than at low food concentration. Mean body length at late instars at 25℃ was longer than at 20℃ at same food levels, while duration of instar was shorter at 25℃ than at 20℃. The maximum of body length (2. 82mm) appeared the sixteen instar at 25℃ and high food concentration,and both the average largest egg production(144 ind.) and maximum of the intrinsic rate of population increase(0.41 ind. day-1) ofS. vetulus occurred at 25℃ and under high food level. The statistical analysis showed that the relationship between egg production and body length ofS. vetulus was positive significance. The threshold food concentration was4 cells mL-1(S. obliquus).The author also discussed the possibility whetherS. vetulus became a suitable species for mass culture at aquiculture.

     

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