Characterization of water quality in shrimp ponds of different sizes and with different management regimes using multivariate statistical analysis

Coastal shrimp aquaculture in Bangladesh is mostly practiced in an agricultural unit called a Gher, which is a special type of agricultural field with elevated surrounding embankments/borders situated by the side of a river that is used to grow rice in winter and shrimp in summer. Ghers of different sizes are managed in different ways. An on-farm project was carried out to study the effects of Gher size and their related management practices on water quality, shrimp production and the economic returns of shrimp farming in the Southwest coastal region of Bangladesh. We present here the results of this project with respect to water quality as explored through factor analysis, which was applied as a way to understand the nature and extent of the effects of different variables. For the majority of the variables and factors, one-half to two-thirds of their variability was explained by changes over time (months), and a further one-quarter to one-third was explained by Gher size and associated management practices. The alternating dry/monsoon season and water management practices determined long-term and large-scale (annual) water exchange in the Ghers that mainly affected processes related to live and dead particles suspended in the water column. Processes related to decomposition and nitrification were more dependent on short-term (days) water circulation in the Ghers, which is turn was reliant on the time span between the exchanges of water in the Ghers and river. Our results show that improved management leads to higher natural and shrimp productivity in the smaller Ghers and strongly support the argument put forward by the policy makers and scientific community in Bangladesh that the smaller the Gher, the better they can be managed and the better the possibility of increased shrimp survival and production.     

From Linderiella baetica to gambilusa: Involving children in conservation by giving a new species a common name

1. The knowledge and awareness that the general public has about aquatic invertebrates is often poor, even when they are highly threatened. The frequent lack of popular names and the unattractiveness of the scientific ones may be among the factors hindering the knowledge of these organisms and, consequently, the awareness of their conservation status and the willingness to conserve them.
2. Linderiella baetica (Crustacea, Branchiopoda, Anostraca) was discovered in 2007 in southern Spain and is considered a critically endangered species. However, being a small invertebrate inhabiting generally unappreciated temporary ponds, this species was completely unknown by the general public, even in the area in which it occurs.
3. To increase the knowledge and awareness of L. baetica, 1,347 children from five schools within its distribution area participated in a contest to select a common name for this newly described taxon. The winning name, gambilusa (Andalusian shrimp), will be used in the future by the Spanish Ministry of Environment and hopefully by the general public to identify the species.
4. The contest was found to have increased the knowledge about the target species in a sustained manner, as 1 year later, 93% of the children recognized gambilusa as a crustacean, 75% remembered its typical habitat, and 89% broadly identified its geographical distribution.
5. This kind of name-choosing contest is applicable for different regions and taxa to raise awareness on the conservation of threatened but poorly known biota.

     

山东黄河沉沙池区综合治理技术及经济效益分析

沉沙池区沙化土地是人为形成的沙地，土壤含沙量高、保水保肥性差、地表凹凸不平。通过平整土地、营建农田防护林体系、改良土壤、发展高效优质农业，池区面貌焕然一新，大大改善了生态环境、提高了土地生产力、增加了群众收入。经过投资效益分析，此项目投入产出比为3．53、投资回收期为2．13a、治理效果良好。     

养殖池塘底泥-水界面营养盐扩散的室内模拟研究:Ⅰ氮的扩散

通过室内模拟试验,对养殖池塘底泥-水界面N营养盐的扩散特点进行了研究。结果表明,池塘淤泥中TN的累积是伴随着池塘有机质的沉积,养殖池塘底泥N的释放形态主要是NH 4-N,DO对N的释放速率的影响具有多重性。DO(溶解氧)影响了有机质的分解速率,从而影响着营养盐的再生速率,DO又影响着微生物对营养盐的消耗水平。养殖池塘N的释放受到泥水两相营养盐平衡机制的制约,只有当水中浓度低于平衡浓度时,才表现为净释放,否则可能出现负释放,平衡浓度受到DO和Eh(氧化还原电位)的影响。     

老化虾池生态系中几类主要细菌的季节变化特征

对青岛市老化虾池生态系中几类主要细菌的季节变化情况进行了研究，结果表明，虾池水体中的异养菌总数在放苗前和养成前期均较低，从养成中期开始逐渐增高，7、8月份菌量达到最高，养成末期逐渐有所下降，总变化幅度为10^3-10^5cells/ml；弧菌数和硝酸盐还原菌数在养殖中、后期增长速度高于其他种类，在总菌中所占比例增大；沉积环境中的3类细菌的数量均比同期水体中的菌量高1-2个数量级，养殖后期和末期菌量仍保持在较高水平，硝酸盐还原菌在总菌量中占较高比例。因此认为，现有老化虾池微生物群落的演变不利于对虾的生长，应对微生态平衡进行人工调控。     

海水养殖池塘溶氧平衡的实验研究↑（*）

采用围隔实验法,研究了施肥养殖台湾红罗非鱼（Ｏｒｅｏｃｈｒｏｍｉｓｍｏｓａｍｂｉｃｕｓ×Ｏ．ｎｉｌｏｔｉｃｕｓ）和投饵养殖中国对虾（Ｐｅｎａｅｕｓｃｈｉｎｅｎｓｉｓ）的海水池塘中溶氧的昼夜平衡。测定了浮游植物光合作用产氧量、水柱呼吸耗氧量和底泥呼吸耗氧量;用估测模型计算鱼、虾呼吸耗氧量及用差减法估计大气扩散作用引起的得氧或失氧。结果表明：在海水池塘溶氧的收入中,浮游植物光合作用产氧占９０％以上,大气扩散溶入低于１０％;在海水池塘溶氧的支出中,水呼吸耗率约占６２．４８％,鱼、虾呼吸耗氧约占１８．１８％,底泥呼吸耗氧约占１９．３５％。且施肥鱼池和投饵虾池的溶氧平衡状况不同     

持续充氧对养殖池塘上覆水—泥水界面—沉积物间隙水中离子垂直分布的影响

为研究底部充氧对养殖系统上覆水—泥水界面—沉积物间隙水中离子垂直分布的影响,在室内条件下构建模拟装置,设充氧组(实验组)和未充氧组(对照组),每组4个平行,利用Peeper技术分别采集各装置中第0、1、4和7天,上覆水—泥水界面—沉积物间隙水整个垂直剖面的原位水样,然后应用微量分光光度法测定样品中的NH_4~+-N、NO_3~-N、NO_2~--N、PO_4~(3-)-P和SO_4~(2-)-S浓度。结果显示:(1)短期充氧对NH_4~+-N在上覆水和沉积物间隙水中的垂直分布特征影响不显著;(2)充氧可使沉积物上覆水和表层沉积物(0~2 cm间隙水中的NO_3~--N浓度大幅升高;(3)硝化作用的中间产物NO_2~--N,由于不能和氧气大量共存,其平均浓度的最大值由未充氧前出现在上层上覆水,逐渐转变为在表层沉积物1 cm深处;(4)充氧促进了沉积物对PO_4~(3-)-P的吸附和固定,显著降低了其在上覆水和表层沉积物(0~2 cm)间隙水中的浓度;(5)充氧通过化学和生物途径氧化了系统中还原性含硫物质,大幅升高了上覆水和表层沉积物(0~2 cm)间隙水中的SO_4~(2-)-S的浓度;(6)主成份分析(PCA)表明,持续充氧1、4和7 d显著改变了上覆水的理化性质,其中第4天和第7天的数据与对照组差异最大,相对于上覆水,充氧对沉积物间隙水的总体影响不显著。研究表明,底部充氧可降低引起池塘富营养化PO_4~(3-)-P的浓度,提高了氧化性离子NO_3~--N、NO_2~--N和SO_4~(2-)-S的浓度,显著改变了上覆水和表层沉积物间隙水的理化性质,是养殖池塘水质调控和环境修复的一种有效方法。     

我国淡水池塘养殖投入产出分析与发展对策

淡水池塘养殖是我国水产养殖业的重要组成部分,其投入产出效益关系一直备受关注。在对10个省份淡水池塘养殖投入产出数据调研的基础上,分析了产出与投入之间的关系,得出结论:(1)典型相关分析发现,淡水池塘养殖产出与投入第一对典型相关变量的相关系数达到强相关水平,值为0.961 3,其中,反映产出的典型变量主要由成鱼收入决定,反映投入的典型变量主要由饲料和苗种费用决定;(2)样本区域淡水池塘养殖产出投入比值介于0.76~1.65之间,效益相差较大,其中浙江最高、辽宁最低。建议通过加大中低产池塘标准化改造力度、构建生态养殖模式及提高养殖合作组织化程度等措施,促进实现我国淡水池塘养殖可持续发展目标。     

微生态制剂对鲤、鲫和草鱼养殖池塘效益的影响

以枯草芽孢杆菌为主的主要用于促进鱼类消化生长的微生态制剂I、多种混合微生物主要用于调节水质的微生态制剂II,或是两者混合使用的方法,比较研究了黑龙江省及辽宁省池塘养殖的鲤（Cyprinus carpio）、鲫（Carassius auratus）和草鱼（Ctenophyargodon idellus）的增重率、饲料系数...     

多营养层次养殖的海水池塘浮游植物群落特征

为了掌握多营养层次养殖的海水池塘浮游植物群落变动情况，并为优化池塘养殖模式和生态调控提供科学依据，在海水池塘“鱼-虾-贝”多营养层次养殖期间，定期进行采样检测，分析水体浮游植物群落及其与营养盐含量的相关性。结果显示，养殖池塘浮游植物种类数高于自然海域，池塘浮游植物细胞密度除养殖初期部分稍低外，养殖中后期均高于自然海域。养殖初期池塘水体浮游植物以中肋骨条藻(Skeletonema costatum)为优势种，中期以锥状斯克里普藻(Scippsiella trochoidea)为绝对优势种，后期以中肋骨条藻、米氏凯伦藻(Karenia mikimotoi)、锥状斯克里普藻为主要种。池塘浮游植物种类多样性指数(H’)、均匀度指数(J)波动明显大于自然海域。池塘浮游植物群落呈现由硅藻占优势向甲藻占优势演替的趋势，而自然海域均以硅藻占绝对优势。米氏凯伦藻细胞密度与活性磷酸盐含量极显著相关。