桑沟湾筏式养鲍区水质分析

Analysis of water quality of abalone suspended long-line mariculture area of Sungo Bay

根据2009年4、6、8、10和12月5个航次的调查数据,分别采用有机污染指数(A)、营养水平指数(E)、营养盐浓度阈值法和化学计量法对鲍区的水质状况进行了分析。通过与海带区、非养殖区同步调查数据以及鲍区历史数据的比较,研究了筏式养鲍对水环境的影响。结果显示,鲍区溶解性无机氮、磷酸盐及硅酸盐的浓度分别在2.02～9.25,0.086～0.420,0.91～18.35范围内,季节变化明显。4、6、12月A值均<0,水质状态良好;8月和10月A值介于0和1之间,水质状态较好,鲍筏式养殖区尚未受到有机污染。E值介于0～0.5,水质营养水平处于贫营养状态。磷酸盐是鲍区、海带区及非养殖区的主要限制因子。鲍区的氨氮及无机氮浓度在8月出现峰值,显著高于海带区和非养殖区,也高于历史数据,可能与鲍的氨氮排泄有关。虽然鲍区目前的水环境状况较好,但是需要注意的是营养盐的结构和季节性变化趋势发生变化。

Abalone long-line culture is a commercially important mariculture method in China.With the development of scale,it is very important and necessary to understand its influence on the environment.In this paper the effects of abalone long-line culture on the water quality were studied,in order to provide basic information for the setup of sustainable mariculture mode.Dissolved nutrients were investigated in abalone long-line mariculture area of Sungo Bay in April,June,August,October and December of 2009.Water quality was assessed by organic pollution indices（A） and eutrophication assessment indices（E）.Nutrient factors limiting the growth of phytoplankton were assessed by the method of theoretical half-saturation constant（Ks）and stoichiometric ratios.By comparison of nutrients in abalone,kelp and no mariculture areas and the historic data,the environmental influence of abalone long-line mariculture was analyzed.Results showed that the concentration of dissolved inorganic nitrogen（DIN）,PO3-4,and SiO2-3 were at the range of 2.73-9.25 μmol/L,0.086-0.42 μmol/L,0.91-18.35 μmol/L,respectively.In April,June and December,A values were lower than 0,water conditions were in good level,in August and October,A values ranged between 0 and 1,water conditions were at preferable level.E values ranged in 0-0.5,which showed that the nutrient concentration was in the poor nutrient condition.This result suggested that the influence of abalone long-line culture on the water quality was limited.However,there were some extent variations between different areas in the nutrients concentration,nutrients structure and seasonal changing trend.P might be the key limitation in the monitoring area.From the historic changing trend,ammonium and DIN enrichment in abalone area in August should be paid more attention to.