大鹏澳海水鱼类网箱养殖对水环境的影响

根据2001~2002年对大亚湾大鹏澳海水鱼类网箱养殖海域水环境的监测资料,分析讨论了网箱养殖对水环境的影响。结果表明,该海域水环境质量较好,除夏季溶解氧(DO)和春季的硫化物浓度超第二类海水水质标准情况较严重外(超标率均为62.5%),其他水环境因子一般不超标。养殖区DO和叶绿素a(Chla)浓度均显著低于对照区(t-test,P<0.05),而NH4-N和PO4-P浓度则一般高于对照区,其他水环境因子的空间分布差异不大。海水CODMn、BOD5和硫化物主要与网箱养鱼生产季节性强的特点有关;而水温、盐度、透明度、悬浮物、DO和pH的季节变化主要受控于大亚湾亚热带季风气候,NO2-N、NO3-N、DIN、PO4-P和SiO4-Si等营养因子的季节变化主要受降雨和浮游植物的影响,Chla的季节变化则主要受水温和N:P比的影响,与网箱养鱼的关系并不明显。

Impact of cage fish farming on water environment in Daya Bay

Water environment monitoring was conducted in the cage fish farm area and its vicinity (as control area) in Dapeng Cove in Daya Bay from 2001 to 2002 on a seasonal basis. The results showed that water quality in the area was in relatively good condition, except the dissolved oxygen (DO) in summer and sulfide in spring both exceeded the criteria of the second class of Sea Water Quality Standards for fisheries in China with exceeding rate of 62.5%, the other water environmental factors were general within the criteria. DO and chlorophyll a (Chl a) in the fish farm were both lower than that in control area significantly ( t -test, P <0.05), while the concentration of NH_4-N and PO_4-P in the fish farm were general higher than that in control area, and other environmental factors did not display evident differences between fish farm and control area. The seasonal variation of COD_ Mn , BOD_5 and sulfide mainly related with the seasonal characteristics of fish farming. The seasonal variation of seawater temperature, salinity, transparency, suspended solid, DO and pH were mainly determined by the subtropic monsoons climate in Daya Bay; the seasonal variation of nutrients such as NO_2-N, NO_3-N, DIN, DIP and SiO_4-Si were mainly regulated by the rainfall and phytoplankton status, and the seasonal variation of Chl a was mainly related with temperature and N:P ratio, so there were no evident relationship between these factors and cage fish farming.