共培养大型海藻对蒙古裸腹溞培养体系的生态效应

Ecological effects of co-culture of macroalgae on water fleas Moina mongolica

为了解大型海藻与盐水枝角类共培养的生态作用,通过大型海藻与蒙古裸腹溞共培养的方法,研究了孔石莼和肠浒苔对共培养水体水质的静态净化效果以及对该溞生殖与种群增长的影响。结果表明:孔石莼和肠浒苔对共培养水体氨氮(NH3-N)、pH和溶解氧(DO)的影响显著(P<0.05)且变化规律基本一致,其中NH3-N在第12 d降到最低(0.016mg·L-1),随后维持在相对稳定范围内;pH和DO随孔石莼和肠浒苔生物量的增加而升高,pH变化范围8.2~9.0,DO变化范围4.2~6.4 mg·L-1;共培养条件下两种大型海藻对蒙古裸腹溞生殖和种群增长的影响表现出明显差异,在孔石莼共培养体系中,蒙古裸腹溞的平均生殖量、内禀增长率rm、周限增长率λ和世代周期T随孔石莼生物量的增加呈波动升高,当生物量为2.5 g·L-1时均达峰值,之后逐渐下降,平均寿命随孔石莼生物量的增加而减少;孔石莼共培养体系显著优于对照组单一蒙古裸腹溞培养效果(P<0.05),而肠浒苔共培养体系与对照组相差不显著(P>0.05)。研究结果证明了孔石莼对共培养体系水质和养殖动物的有利作用,即共培养一定生物量(2.5~3.5 g·L-1)的孔石莼不但有利于培养水体中NH3-N、DO等水质净化,还可以促进蒙古裸腹溞的生长与繁殖,为蒙古裸腹溞规模化培养工艺优化与新模式构建提供了科学依据。

To clarify ecological effects of co-culture of macroalgae and saline cladocerans,two co-culture aquatic systems were established via addition of macroalgae,i.e.Ulva pertusa or Ulva intestinalis,into the static culture water with water fleas Moina mongolica.We investigated the impacts of those two macroalgae on the static water purification effect and the reproduction and population performance of the water fleas.The results showed that the two macroalgae had significant effects on the levels of ammonia,pH and DO in the co-cultured water(P<0.05).The water chemical parameters varied in a similar pattern for both systems.The levels of ammonia in both systems decreased to the minimum value(0.016 mg·L-1)after 12 days,and then kept stable.Both pH value and DO level were elevated with increasing biomass of the two macroalgae.The pH values varied between 8.2 and 9.0 and DO levels between 4.2 and 6.4 mg·L-1.The two macroalgae differentially affected the reproduction and population growth of M.mongolica in the coculture systems.The average neonates,intrinsic increase rate(rm),finite increase rate(λ),and generation cycle(T)were increased with the increases of U.pertusa biomass.When U.pertusa biomass peaked at 2.5 g·L-1,those parameters declined.In contrast,the average lifespan declined with the increasing biomass of U.pertusa.There were better ecological effects in the coculture system based on U.pertusa than in the control.There was no significant difference between co-culture system based on U.intestinalis and the control(P>0.05).U.pertusa,with the biomass of 2.5 to 3.5 g·L-1,played dual roles in both water purification and culture of aquatic animals in the co-culture system,beneficial to the purification of ammonia and DO in water and the growth and reproduction of M.mongolica.These findings provide useful insights into optimization of a large-scale culture technique and development of novel culture mode for M.mongolica.