唐岛湾网箱养殖对水环境的影响

Effect of Net-cage Culture on Water Environment in Tangdao Bay

2004-08～2005-05分4个航次对唐岛湾网箱养殖区的水环境进行了现场调查,分析讨论了网箱养殖对水环境的影响。结果表明,唐岛湾网箱养殖对海水的水温、盐度、透明度、DO、pH的影响不显著,对叶绿素a浓度的影响显著(t-test,P<0.05)。养殖区CODMn虽然也显著高于对照点,但主要受陆源污染的影响,与网箱养殖关系不大。养殖区和对照点海水中无机氮的主要形态均以NO-3-N为主,其次是NH+4-N,NO2--N最少,DIN、3种形态无机氮、无机磷的季节变化趋势也比较一致。除了NH+4-N外,唐岛湾网箱养殖对溶解态无机氮磷营养盐(NO3--N、NO-2-N、DIN、PO34--P)的影响并不显著(t-test,P>0.05),但养殖区内的含量比对照点有了一定程度的升高。以DIN和PO43--P作为N、P阈值来分析,目前唐岛湾网箱养殖区的水质未超出二类水质标准。唐岛湾网箱养殖区海水各季节的营养指数E值均小于1,表明养殖区的水质状况尚未达到富营养化水平。

Based on the field data measured during 4 cruises from August 2004 to May 2005, the effect of net-cage culture on water environment of Tangdao Bay was analyzed. The results showed that there was no significant effect of net-cage culture on water temperature, salinity, transparency, dissolved oxygen and pH, while the concentration of chlorophyll a in the culture area was higher than that in control point significantly （P〈0.05）. Although CODMn was also higher than control point significantly, it was mainly affected by land-based pollution and had no evident relationship with net-cage culture. The main form of inorganic nitrogen in both culture area and control point was NO3^--N. The seasonal change of dissolved inorganic nitrogen （DIN） and NO3^--N, NO2^--N, NH4^＋-N, PO4^3--P in culture area and control site varied similarly. Except for NH4^＋-N, the concentration of NO3^--N, NO2^--N, DIN and pO4^3--P showed no significant differences between culture area and control point （P〉0.05）, but the concentrations in culture area were much higher than those in control point. According to the DIN and PO4^3- -P standard, the water quality of Tangdao bay did not exceed the criteria of the second class of Sea Water Quality Standards for fisheries in China. The nutrient indexes in the four seasons were all less than 1, indicating that the environment did not reach eutrophic state yet.