江蓠对对虾排出氮磷的吸收

Absorption of nitrogen and phosphorus from shrimp culture water by Gracilaria

通过研究来自斑节对虾养殖水和人工配方2种不同来源的氮、磷对细基江蓠繁枝变种的生长及生化成分的影响,以及不同温度下斑节对虾氮磷排出率与细基江蓠繁枝变种对氮、磷吸收率这2种代谢率之间的关系,探讨江蓠对对虾排出氮、磷的利用和水质净化时江蓠与对虾的定量关系.在不同营养来源的生长实验中,细基江蓠繁枝变种的日生长率随氮浓度的升高而增大,其粗蛋白含量也随氮浓度的升高而增加.但在相同可溶性无机氮、磷浓度下,不同营养盐来源间细基江蓠繁枝变种的日生长率及藻体的成分组成没有差异(p>0 05).这表明,对虾养殖水中影响细基江蓠繁枝变种生长的主要营养盐形式是可溶性无机氮、磷.而对虾排出氮磷与藻吸收的实验结果显示,随着温度的升高,虾的氮排泄速率升高,而细基江蓠繁枝变种对氮的吸收速率在20～28℃内变化不大,在32℃时明显比其它温度下的小(p<0 05).在20,24℃时斑节对虾的磷排泄速率小于细基江蓠繁枝变种对磷吸收速率,在28,32℃时则相反.吸收1g虾排出的氮所需的细基江蓠繁枝变种的量由20℃时的1 93g上升到32℃时的13 17g;吸收1g虾排出的磷所需的细基江蓠繁枝变种的量由20℃时的0 55g上升到32℃时的1 17g.因此,采用该藻处理养殖水时,参考水中氮、磷动态来确定藻投放量是提高净化效果的关键之一.

This study was preformed to assess Gracilaria tenuistipitata var. liui Zhang et Xia absorption of the nitrogen and phosphorus from Penaeus monodon culture water and quantitative relation between Gracilaria and the shrimp during aquaculture water treatment. The Growth and the chemical composition of G. tenuistipitata var. liui Zhang et Xia fertilized by two sources——the synthetical fertilizer and the culture filtrate from Penaeus monodon, the nutrient absorption rates of the alga, and the nutrient excretion rates of the shrimp were measured. The result of the growth experiment showed that the daily growth rates and the crude protein content of G. tenuistipitata var. liui Zhang et Xia became higher with the increase of nutrient concentrations. However, in the same concentrations of the inorganic dissolved nitrogen and phosphorus, the daily growth rates and tissue components of the algae cultured with the different nutrient resources were statistically indistinguishable (p<0.05). The result suggested that the inorganic dissolved nitrogen and phosphorus were the main nutrient factors that influenced the growth of the alga cultured in shrimp culture filtrate. The relation between nutrients excreted by the shrimp and nutrients absorbed by the alga was examined in the second experiment. The trend of the nitrogen excretion rate of shrimps went up with rising temperatures, but the nitrogen adsorption rates of G. tenuistipitata var. liui Zhang et Xia were statistically equivalent at 20℃～28℃, decreasing significantly at 32℃(p<0.05). At temperatures of 20℃ and 24℃,the phosphorus excretion rate of the shrimp was less than the phosphorus absorption rate of the alga, and it is reverse at 28℃ and 32℃. It needed 1.93?g of the alga at 20℃ and 13.17?g at 32℃ to absorb the nitrogen excreted by 1g of the shrimp, but for phosphorus, 0.78?g at 20℃ and 1.17?g at 32℃ was needed, respectively. Therefore, if Gracilaria tenuistipitata var. liui Zhang et Xia was used to treat shrimp aquaculture water, estimation of the algal biomass added into the water basing on nitrogen and phosphorus excreted by shrimps plays a role in the effect of the treatment.