寡盐水鱼池藻菌土腥异味化合物研究

通过利用固相微萃取-气质联用色谱测定天津市寡盐水养鱼池中浮游藻类和放线菌的次生代谢产物——土腥异味化合物（土臭味素和二甲基异莰醇）浓度,感官评价养殖鱼土腥异味程度,同时测定浮游藻类和放线菌生物量,探讨鱼池中土臭味素和二甲基异莰醇浓度、浮游藻类和放线菌生物量以及养殖鱼异味之间的相互关系。结果表明,寡盐水养鱼池水体中普遍存在土臭味素和二甲基异莰醇,其中二甲基异莰醇是鱼池中的主要异味物质,浓度0．33—5302．70ng·L^-1,土臭味素浓度相对较低,0．29～12．10ng·L^-1。养鱼池中共测到6门94属的浮游藻类,生物量0．07～186．48mg·L^-1,以蓝藻Cyanophyta、裸藻Euglenophyta等种类为主。放线菌共测到3个属,总生物量0．01×10^4-1．50×10^4个·L^-1,以链霉菌属Streptomyces为主。巨颤藻Oscillatoria princeps和放线菌是天津地区寡盐水养鱼池中能够产生二甲基异莰的主要产源。水体异味和鱼肉发生异味不同步。     

盐度对早期链霉菌产生二甲基异莰醇和土臭味素的影响

天津是中国北方重要的渔业生产基地,2006年全市水产养殖面积430 km2,水产品总产量35.5万吨,其中养殖产量30万吨,渔业产值40亿元。天津养鱼池水盐度普遍在2-5,属于寡盐水鱼池,但在该地区采取高密度精养模式生产鱼类普遍存在土腥异味,降低了水产品食用价值和养殖效益。     

天然水体中两种主要异嗅物质的来源及迁移转化研究进展

近年来,水中嗅味问题逐渐引起关注。研究发现,天然水体中异嗅物质主要是微生物和藻类的挥发性次级代谢产物。总结了天然水体中常见的两种异嗅物质土臭素(GSM)和二甲基异莰醇(MIB)的来源及其在生物体内的合成途径。介绍了异嗅物质通过吸附、挥发、光解、生物降解等一系列作用在饮用水水源中的迁移转化以及其进入水体生物的途径。     

杭州西湖浮游藻类变化规律与水质的关系

于2006～2007年对杭州西湖浮游藻类的种类及个体丰度进行初步研究,并依据<水和废水监测分析方法>对其水质现状进行了生物学评价.综合生物和理化指标数据,对杭州西湖的水质作一总体评估,并对西湖水中的物种多样性保护及水质的可持续利用提出了建议.共鉴定浮游藻类179种,其中蓝藻25种,隐藻1种,金藻3种,甲藻3种,黄藻5种,裸藻23种,硅藻41种和绿藻78种.分析了杭州西湖浮游藻类的组成和分布的特点,揭示出西湖浮游藻类的种类组成与西湖水质变化之间的关系.结果表明:藻类的组成和分布与水质变化规律基本吻合,西湖水质较整治前有明显的改善,一些清水藻类的物种逐步增多.     

背角无齿蚌(Anodonta woodiana)对浅水系统底栖和浮游藻类竞争关系的影响

底栖藻类和浮游藻类之间的竞争关系对浅水生态系统的结构、功能具有重要的影响,双壳类可通过滤食控制浮游藻类,从而改变底栖藻类与浮游藻类之间的竞争结果。论文通过比较放养背角无齿蚌(Anodonta woodiana)(蚌处理组)与不放养背角无齿蚌(对照组)系统中底栖藻类、浮游藻类的生物量和优势种等的变化,研究了滤食性双壳类对底栖藻类和浮游藻类间竞争的影响。结果表明,背角无齿蚌可显著降低浮游藻类生物量,提高水体透明度和沉积物表面光照条件,从而显著提高底栖藻类的生物量;背角无齿蚌也改变了浮游藻类的优势种,使优势种由蓝藻转变成硅藻。因此,滤食性双壳类有利于促进浅水生态系统从混水态向清水态转变,本研究结果对富营养化浅水湖泊修复与管理具有一定的参考意义。     

安康水库表层浮游藻类群落结构及其与环境因子的关系

为了解安康水库表层水质与浮游藻类群落现状以及浮游藻类群落结构与环境因子之间的关系,于2012年1—12月对水库表层水进行每月一次的采样,分别对浮游藻类分布状况和理化因子进行分析.利用Shannon指数(H)和Pielou均匀度指数(J)分析浮游藻类群落特征,根据理化指标和综合营养状态指数(TSI)评价水体营养状态.共检测到浮游藻类7门110属,丰度为0.11×10⁴～2.08×10⁴ cells·L^-1.藻类组成、污染指示种分布情况、多样性分析和TSI显示安康水库表层属于中污染水质,处于中营养状态.此外,高密度投饵水产养殖及生活污水直接排放入库对水质产生负面影响,支流岚河的水质状况也较差.典范对应分析(CCA)结果显示,测定的8个环境因子中,不同季节影响浮游藻类群落组成及分布的环境因子不同,且氮是影响浮游藻类组成的主要营养盐因子.理化指标分析显示,安康水库表层水大体满足Ⅱ类水标准,水质良好.但部分采样点的总氮出现差于Ⅱ类水标准的现象,表明安康水库水质有变差的趋势.     

金沙江上段浮游藻类和着生藻类群落格局及其与环境因子的关系比较研究

比较河流浮游藻类和着生藻类群落的时空格局及其与环境因子关系的差异,有助于了解两类藻的区别与联系。然而,目前这方面的研究还不多。基于2019年秋季和2020年夏季金沙江上段干流17个样点藻类及水体理化指标的调查数据,分析了不同季节浮游藻类和着生藻类群落结构及其主要环境驱动因子,比较了两类藻的多样性格局及其与环境关系的异同。结果发现,调查河段的浮游藻类和着生藻类均以硅藻为主,其中浮游藻类以极小曲壳藻(Achnanthes minutissima)、钝脆杆藻(Fragilaria capucina)、适中舟形藻(Navicula accomoda)为主要优势种,着生藻类以极小曲壳藻(Achnanthes minutissima)、扁圆卵形藻(Cocconeis placentula)、橄榄绿色异极藻(Gomphonema olivaceum)为主要优势种。浮游藻类和着生藻类秋季平均密度分别为:2.41×10~5个/L、9.43×10~3个/cm~2,均明显高于夏季的平均密度(4.84×10~4个/L、4.84×10~3个/cm~2)。两类藻的群落格局表现出明显的季节变化,但只有着生藻分类单元...     

轮纹异痂蝗卵的过冷却能力与其体内水分和生化物质含量的关系

【目的】低温是影响昆虫生长发育和存活的关键因子之一。为明确轮纹异痂蝗Bryodemella tuberculatum dilutum卵的抗寒性及其机理, 研究了其过冷却能力与其体内水分及其他抗寒性相关生化物质含量的关系。【方法】采用热电偶法测定了轮纹异痂蝗卵的过冷却点,同时采用烘干法、残余法、氨基酸自动分析仪和高效液相色谱法分别测定了其卵的含水量、脂肪、氨基酸及小分子糖醇的含量。【结果】土壤含水量对轮纹异痂蝗滞育前卵的含水量、脂肪含量（鲜重）及过冷却点有极显著的影响(P<0.01)。随着土壤含水量从4%增加到13%,卵含水量从45.12%上升到55.25%,卵脂肪含量（鲜重）从10.39%下降到9.39%,而过冷却点从-30.11℃上升到-25.69℃。不同发育阶段卵的过冷却点、含水量、脂肪、氨基酸及小分子糖醇含量存在极显著差异(P<0.01)。从卵产下当天至120 d,卵过冷却点从-26.78℃下降至-30.18℃,含水量从51.93%下降至46.69%,脂肪含量分别从9.99%（鲜重）和17.37%（干重）上升至13.92%(鲜重)和25.29%（干重）。滞育卵的过冷却点显著低于滞育前卵的过冷却点。从卵中共检测到17种氨基酸,其中5种与过冷却点存在显著的相关关系(P<0.05)。卵过冷却点随着甘氨酸和脯氨酸含量的升高而降低,而随着胱氨酸、亮氨酸及天冬氨酸含量的增加而升高。随着卵的发育,海藻糖、甘油、肌醇和山梨醇含量逐渐上升,而葡萄糖和果糖含量逐渐下降。在卵发育过程中,海藻糖和甘油的含量显著高于其他4种物质的含量。卵过冷却点与上述6种小分子糖醇均存在显著的相关关系,其中与海藻糖和葡萄糖的相关性最强。过冷却点随海藻糖、甘油、肌醇和山梨醇含量的升高而降低,而随葡萄糖和果糖含量的升高而上升。【结论】轮纹异痂蝗卵在发育过程中,通过降低含水量,积累脂肪、脯氨酸、甘氨酸及海藻糖、甘油、肌醇和山梨醇等抗寒物质,从而提高其过冷却能力。     

The potential of fish production based on periphyton

Periphyton is composed of attached plant andanimal organisms embedded in amucopolysaccharide matrix. This reviewsummarizes research on periphyton-based fishproduction and on periphyton productivity andingestion by fish, and explores the potentialof developing periphyton-based aquaculture.Important systems with periphyton arebrush-parks in lagoon areas and freshwaterponds with maximum extrapolated fish productionof 8 t ha^–1 y^–1 and 7 t ha^–1y^–1, respectively. Experiments with avariety of substrates and fish species havebeen done, sometimes with supplemental feeding.In most experiments, fish production wasgreater with additional substrates compared tocontrols without substrates. Colonization ofsubstrates starts with the deposition oforganic substances and attraction of bacteria,followed by algae and invertebrates. Afterinitial colonization, biomass density increasesto a maximum when competition for light andnutrients prevents a further increase. Often,more than 50% of the periphyton ash-free drymatter is of non-algal origin. Highest biomass(dm) in natural systems ranges from 0 to 700g m^–2 and in aquaculture experiments wasaround 100 g m^–2. Highest productivity wasfound on bamboo in brush-parks (7.9 gC m^–2 d^–1) and on coral reefs (3 gC m^–2 d^–1). Inorganic and organicnutrients stimulate periphyton production.Grazing is the main factor determiningperiphyton density, while substrate type alsoaffects productivity and biomass. Better growthwas observed on natural (tree branches andbamboo) than on artifical materials (plasticand PVC). Many herbivorous and omnivorous fishcan utilize periphyton. Estimates of periphytoningestion by fish range from 0.24 to 112 mg dm(g fish)^–1 d^–1. Ingestion rates areinfluenced by temperature, fish size, fishspecies and the nutritional quality of theperiphyton. Periphyton composition is generallysimilar to that of natural feeds in fishponds,with a higher ash content due to the entrapmentof sand particles and formation of carbonates.Protein/Metabolizable Energy (P/ME) ratios ofperiphyton vary from 10 to 40 kJ g^–1.Overall assimilation efficiency of fish growingon periphyton was 20–50%. The limited work onfeed conversion ratios resulted in valuesbetween 2 and 3. A simple simulation model ofperiphyton-based fish production estimates fishproduction at approximately 2.8 t ha^–1y^–1. Together with other food resources infishponds, total fish production with thecurrent technology level is estimated at about5 t ha^–1 y^–1. Because grazingpressure is determined by fish stocking rates,productivity of periphyton is currently themain factor limiting fish production. Weconclude that periphyton can increase theproductivity and efficiency of aquaculturesystems, but more research is needed foroptimization. Areas for attention include theimplementation and control of periphytonproduction (nutrient levels, substate types andconformations), the ratio of fish to periphytonbiomass, options for utilizing periphyton inintensive aquaculture systems and with marinefish, and possibilities for periphyton-basedshrimp culture.     

Studies on Stabilization Ponds for Domestic Sewage in India

For one year a single cell stabilization pond, T. T. Nagar, Bhopal (August, 1968 to July, 1969) and series stabilization ponds, Shahpur, Bhopal (January, 1969 to December, 1969) were studied. Climatological conditions in Bhopal were favourable for the treatment of sewage in stabilization ponds. There was a considerable reduction in BOD, total nitrogen, phosphate, coliforms and enterococci during the process of treatment. The reductions were highest in series ponds. Studies on diurnal variations showed that highest pH, dissolved oxygen, algal cell number and lowest alkalinity values occurred around 4.00 p.m. Algal flora present in the single cell pond consisted of 31 species representing 27 genera. In the series ponds 33 species belonging to 30 genera and 37 species belonging to 33 genera were recorded for the primary and secondary ponds, respectively.     

Effects of 2-methylisoborneol (MIB), and ethanol on the expression and activity of cytochrome P450s from the channel catfish

Injection of 1 mg kg⁻¹ of 2-methylisoborneol (MIB) caused an increase in a CYP1A-like protein of approximately 56 kDa from the kidneys of juvenile channel catfish as determined by western blot analysis using antibodies raised against trout CYP1A1. Ethoxyresorufin O-deethylase activity from kidneys of MIB-injected fish was significantly elevated as compared to ethanol-injected controls. Static exposure of juvenile channel catfish to 10 ppm MIB caused a statistically significant induction of a CYP2K-like protein of approximately 53 kDa from the livers of treated catfish as determined by western blot analysis using antibodies raised against trout CYP2K1. Treatment of juvenile channel catfish with ethanol (1 ml kg⁻¹) reduced the expression of one kidney and two constitutive liver P450s, while increasing another kidney form. There was no difference in carbon tetrachloride-induced lipid peroxidation in livers after ethanol treatment. Thus, MIB and ethanol affect the expression of at least three P450 isoforms in channel catfish tissues.     

Impact of fishery management on Cladoceran populations

Zooplankton of the fish pond reveals a two-year periodicity, which is induced by the two-year cycle of fishery management. In the first year of each cycle, the biomass of large cladocerans prevailed — mainly adult specimens of the species Daphnia pulicaria Forbes, which were absent in the second year. The species Daphnia galeata Sars was present in both years, however, it is more numerous in the second year. The fraction of small zooplankton (rotifers, nauplii, Bosmina, newborn Daphnia) was abundant in the second years, but scarce in the first years, respectively.