养殖密度对工厂化对虾养殖池氮磷收支的影响

Effect of stocking density on input and output of nitrogen and phosphorus in super-intensive shrimp farming pond

本实验设置300尾/m3、600尾/m3、1 200尾/m3和1 800尾/m3 4个养殖密度,探讨了工厂化对虾养殖池中养殖密度对氮磷收支的影响.结果表明,饵料对系统氮、磷的贡献率分别为84.3%～98.3%和93.2%～97.3%,且随养殖密度的增加而提高;通过水层输出的氮、磷分别为总输出量的27.5%～36.3%和8.4%～23.9%,通过底泥沉积的氮、磷分别为总输出量的30.9%～43.9%和51.5%～62.3%.结果说明,在系统氮磷的总输出中,水层输出和沉积均占到了相当的比重,相比较而言,沉积作用更为重要.养殖密度增加会在一定程度上降低水层和提高底泥沉积的氮磷量;总氮磷的投入中有14.5%～28.7%的氮和7.4%～16.5%的磷最终转化为对虾生物量,表现为随养殖密度的增加而降低;池壁附着物中积累的氮磷量在总氮磷输出中所占比重较小,分别为0.3%～3.2%和0.2%～3.0%,且其比重随养殖密度的增加而降低.结果说明,养殖密度显著影响对虾工厂化养殖池氮磷的收支.

In this study,four shrimp stocking densities were designed which were 300、600、1 200 and 1 800 shrimps per m3 respectively,to analyze the effects of stocking density on input and output of nitrogen and phosphorus.The experiment lasted for 63 days.The results showed that 84.3%-98.3% nitrogen and 93.2%-97.3% phosphorus of total input were from feed,and the proportion increased with stocking density.The major outputs of nitrogen and phosphorus were sediment(30.9%-43.9% and 51.5%-60.7%) and water exchange(27.5%-36.3% and 8.4%-23.9%).Nutrient budget showed that only 14.5%-28.7% nitrogen and 7.4%-16.5% phosphorus of the total input were transformed into harvested shrimp finally.The proportion increased with stocking density reducing.The minor outputs of nitrogen(0.3%-3.2%) and phosphorus(0.2%-3.0%) were from the matters attached on pond walls,and the proportion reduced with stocking density increasing.The results indicated that the nitrogen and phosphorus inputs and outputs were significantly different among stocking densities.