生物操纵法对养殖水体富营养化防治的探讨

养殖水体的富营养化无论对海水养殖还是淡水养殖都是一个不可忽视的问题。水体富营养化防治的措施过去都集中在理化方法和工程措施。本文初步探讨了利用生物操纵的方法，即从生态系统结构和功能的调整来进行治理，并对此项技术在我国的应用前景做了可行性分析。  

杭州湾富营养化及浮游植物多样性问题的探讨

根据杭州湾水质监测及浮游植物的调查资料,应用营养状态指数、生物多样性和相似性指数等概念,分析了杭州湾的富营养化及浮游植物多样性等问题.研究表明,杭州湾营养状态指数由近岸向外海递减,COD、DIN和DIP在杭州湾营养状态指数的构成比例中分别占64.3%、34.6%和1.1%;浮游植物种类多样性指数自西北向东南呈递减-递增-递减的态势,其低谷区中心轴位于121°121＇E、30°00＇N-122°30＇E、31°00＇N连线(图1的A-A＇线)附近;营养状态指数和浮游植物种类多样性指数的相关性好,外海侧海域因为二者呈负相关而更有可能成为赤潮发生的"危险区";杭州湾浮游植物生长环境大致可以A-A＇线为界划分为近岸侧和外海侧两个区,前者生长环境比后者更为恶劣;浮游植物按其物种相似性指数可分为外海群落与近岸群落,它们的地理.分布同样可以上述连线为界.  

湖库富营养化人工神经网络评价模型

在分析现有应用人工神经网络评价模型局限性的基础上，根据湖库富营养化的评价标准，提出了生成BP神经网络训练样本、检验样本和测试样本的新方法，给出了区分湖库富营养化不同程度的分界值，论述了确定合理隐层及其节点数的方法，使得训练后的神经网络模型具有更强的泛化能力，不受初始连接权值的影响。训练后的评价模型应用于实例的评价结果表明，新的评价模型具有更好的客观性、强壮性、通用性和实用性。并且由于评价结果采用连续函数输出，能够比较精细地分析湖库的富营养化程度。  

养殖水体氨氮积累危害与生物利用

在养殖水体中,有机污染物包括氮、碳、磷、硫四种主要物质,而后三者形成的产物在氧气充足的条件下对鱼类的影响程度不是太大,当氮以分子氨态或亚硝酸盐氮态存在时,却会对水生动物产生很强的神经性毒害.当前以强饲为特征的集约养殖方式加大了水体有机氮物质分解转化的负荷,微生物分解环节严重受阻,从而成为水体系统循环过程的制约瓶颈,造成水体富营养化甚至污染,引发出诸多病害、药残、食品隐患等问题.水体系统的氨氮循环及污染治理已成为世界性关注的环境问题和研究热点.  

浙江北部沿海富营养化的评价与分析

运用模糊集合论中的权距离要领结合隶属度的模糊评价方法，以化学耗氧量，总无机氮，活性磷酸盐和生物学参叶绿素a为指标，对浙江北部沿海的富营养化状况进行了评价，评价过程中的重 权向量通过改进的层次分析法来确定，并对评价指标重要性比较矩阵进行了不同的调整和对比分析，评价结果以隶属法和累加法两种方式给出，结果表明，浙江北沿海约76．6％的调查海域处于中营养和中富营养状态之间，低于和高于此状态扮别占16．6％和6．7％，评价指标重要度的不同排列会对最终评价结果产生影响，累加法的评价结果比隶属法更接的接近实际，富营养化程序高低与赤潮发生的相准相性尚需要进一步研究。  

江蓠作为富营养化指示生物及修复生物的氮营养特性

近海环境的污染日趋严重,化学监测方法存在着其固有的缺陷,采用指示性生物来反映变化的水质已越来越为人们所接受.大型海藻江蓠(Gracilaria)为自养生物,易养殖,能忍受盐度、温度等环境条件相对较大的波动,是理想的研究材料;它能对环境中不同形态氮的浓度及来源,通过氨基酸组成、光合色素及组织氮含量等变化作出迅速而灵敏的响应;江蓠生长快,具有大的氮储存能力,及较高的经济价值等特性,已成为水体中营养变化的指示性生物及治理富营养化理想的修复植物.  

罗非鱼对蓝藻的摄食消化及对富营养化水体水华的控制

2000年至2003年实验研究尼罗罗非鱼对铜绿微囊藻摄食、消化特性的基础上,在宁波月湖等富营养化景观水体进行了罗非鱼控制蓝藻水华的应用试验。研究表明,罗非鱼对水华蓝藻有很强的摄食与消化能力。25℃条件下,罗非鱼鱼种对铜绿微囊藻的平均消化率达67.5%,摄食率则随鱼体体重及水温的升高而增加。1999年至2000年蓝藻泛滥的月湖水体,2001年和2002年先后放养鲢鳙蚌(9.8g.m-3)和罗非鱼鱼种(3~5g.m-3)后,蓝藻水华不再出现,浮游藻类年平均细胞数量分别比2000年下降67.5%和79.6%,年平均生物量分别下降48.6%和63.8%;蓝藻占浮游植物生物量的比例由2000年的70.0%分别下降至22.1%和11.2%,水体透明度则由之前的20~50cm上升至55~137cm。在已经发生严重蓝藻水华的镇海公园等水体中,放养罗非鱼鱼种(8~15g.m-3)20d左右,水华消失,叶绿素含量和浮游植物数量显著下降,水体透明度明显提高。罗非鱼放养对水体氮、磷等营养盐指标的影响存在较大的不确定性,可能与系统初始的群落结构、营养状态及水体所承受的营养物负荷存在更大的关系。罗非鱼放养应是控制富营养化水体蓝藻水华的理想措施之一。  

沉水植物在富营养化水体生态恢复中的作用及前景

阐述了沉水植物的生态适应性及其在富营养化水体生态恢复中维护生态完整性和稳定性、净化水质、抑制藻类生长的生态功能和作用;分析了富营养化水体沉水植物衰退或消亡的原因、生态恢复研究取得的成就和实际应用中面临的困难,展望了沉水植物恢复在富营养化水体水环境质量改善方面的应用前景。  

我国赤潮频发现象分析与海藻栽培生物修复作用

In this paper, the history, main events and present status of red tide (HAB, harmful algal blooms) along China coast in recent years were reviewed and presented. It showed that the HAB's frequency and scale, number of HAB spec ies, percentage of toxic HAB events and the degree of damages to marine environment and economy have sharply increased in China since 1960's. Eutrophication was key factor for high occurrence of red tide. In this paper, main causes of frequent HAB occurrence along China coast was discussed. Many factors might influence the occurrence of red tide, which included weather, climate, coastal current, tidal current, water temperature, salinity, hydrodynamic and nutrient conditions, trace metals and the variation of biological environment. Numerous evidences from all over the world revealed the linkage between the increases in nutrient loading and the occurrences of high biomass blooms. Eutrophication was one of the important causes that involved in high occurrence of HAB. The main sources of nutrients potentially stimulating HABs included terrestrial runoff, aquaculture selfpollution, atmospheric deposition, sea projects and other pollution events in the ocean. Studies showed that the input from land contaminations and the selfpollution of marine aquaculture accelerated eutrophication in coastal waters and were also important impact factors on red tide. Researches suggested that nutrient composition could affect the species composition of phytoplankton as well as the development of some HABs. The changes in nutrient supply ratios, primarily N∶P, often resulted in shifts in red tide species composition. The correlation between cysts and formation of HAB was discussed from the viewpoi nt of transformation of cyst and vegetative cell, the effects of trace elements and other organic substances on the occurrence of HAB were presented also. It indicated that the nutrient control could be an effective way to reduce the risk of red tide occurrence. Seaweed would play an important role for decreasing marine eutrophication. Among the different methods of red tide controlling studied, seaweed biomass has received much attention due to the cost saving, low sensitivity to environmental and impurity factors, the possible contaminant recovery from the biomaterial and its elevated adsorption capacity. Cultivated seaweeds have very high rates of productivity higher than that of seaweed in its natural habits and grow well in water bodies with higher nitrogen and other nutrients. Seaweeds are able to absorb large quantities of nitrogen, phosphorus and carbon dioxide, produce large quanti ties of oxygen, and have excellent effect on decreasing eutrophication. Large amounts of C, N and P are accumulated into seaweed tissues as they accumulate considerable biomass over a period of months or years depending on the cultivation season. When seaweeds are harvested, nutrients are removed from the sea area. An investigation was carried out for inorganic nitrogen and inorganic phosphorus concentration at Lusi Coast, Qidong County, Jiangsu Province in China, where there were about 270 hm2 for Porphyra yezoensis cultivation with eutrophic sea water in recent years. While during Porphyra yezoensis cultivation, from Sep 2003 to May 2004, the concentration of ammonium nitrogen declined form 0.511-0.778 mg·L^-1 to 0.006-0.057 mg·L^-1, nitrite nitrogen concentration declined from 0.010-0.040 mg·L^-1 to 0.001-0.009 mg·L^-1, and nitrate nitrogen concentration declined from 0.466-0.549 mg·L^-1 to 0.286-0.0568 mg·L^-1, the average concentration of inorganic phosphorus declined from 0.024 mg·L^-1 to 0.019 mg·L^-1. Furthermore, during five hours, the concentration of ammonium nitrogen in the seawater declined form 220.88 μmol·L^-1 to 8.59 μmol·L^-1 by cultivated Gracilaria lemanaiformis, and the concentration of ammonium nitrogen declined form 213.84 μmol·L^-1 to zero by cultivated Enteromorpha clathrata. Other bioremediation mechanisms of seaweed inhibiting the red tide microalgae such as nutrients competition and allelopathic effects were also discussed.  

微生物制剂在水产养殖中应用的研究

实验研究了2种微生物制剂对养殖水体的理化指标、藻类和浮游动物的种群结构等生态因子的影响。结果表明，微生物制剂不仅能够提高鱼的抗病能力，防治鱼病，而且能够促进鱼的生长发育，提高饵料的效率。微生物制剂影响藻类种群的组成、数量和生物量，不仅能够使藻相比较复杂，而且使鱼类易于消化吸收的藻类增加，而使代表水体富营养化的藻类降低；微生物制剂还具有影响养殖水的理化环境，改善池塘底泥等作用。