对虾海水高密度养殖后期水质因子的昼夜变化规律

2008年7月5～6日,对广东汕尾红海湾对虾养殖场养殖87～88d的海水高密度半封闭养殖虾池水质进行每4h监测分析,旨在了解养殖后期昼夜水质变化状况,为合理和即时调控养殖后期水质提供相关理论数据。结果显示,24h内水质指标除化学需氧量（COD）和无机氮（DIN）基本稳定外,其他因子均有较大波动。其中氨氮（NH4＋-N）在3：00达到高峰,5：00落至低谷,9：00又达到高峰;亚硝酸盐氮（NO2--N）的变化却相反,在3：00落至低谷,5：00达到高峰,9：00又落至低谷;pH和溶解氧（DO）均在5：00降至最低,13：00上升到最高。结果表明,3：00～9：00是虾池水质变动的关键时期,应留意水质变化,适时采取合理增氧措施并投洒相应水质调节剂以提高ρ（DO）,减少NH4＋-N和NO2--N产生及降低其毒性。

Diurnal variation of water quality factors in late period of intensive seawater shrimp culture

On July 5～6,2008,we carried out a survey on the intensive semi-enclosed seawater shrimp ponds at Honghai Bay,Shanwei,Guangdong which had cultured shrimps for 87～88 d,monitoring the water quality every 4 h to study the diurnal variation of water quality in the late culture period and to provide theoretical reference for a reasonable,instant water quality regulation for that period.Results show that most water quality factors have an obvious diurnal variation except COD and DIN.NH＋4-N peaks at 3：00 and 9：00 and bottoms at 5：00 while NO-2-N bottoms at 3：00 and 9：00 and peaks at 5：00.Both pH and DO bottom at 5：00 and peak at 13：00.Therefore,the water quality changes quickly during 3：00～9：00,and it is important to pay attention to the variation and take measures such as adding water quality regulator to increase DO value,and to reduce the production of NH＋4-N,NO-2-N and their toxicity.