Distribution patterns of saprolegniosis cutaneous lesions in wild and farmed brown trout (Salmo trutta L.) obtained using a geographic information system (GIS)

A retrospective study was conducted using 250 clinical records of brown trout (Salmo trutta L.) with saprolegniosis by Saprolegnia parasitica, which had been collected from 8 rivers and 1 fish farm in the province of León (Spain). A geographic information system (GIS) was used to obtain skin lesion distribution patterns in males and females. Lesions in wild brown trout affected 15.31 ± 13.33% of the body surface, with a mean of 12.76 ± 6.56 lesions per fish. In addition, 51.23% of wild trout presented lesions with necrosis of the skin or fins. The pattern obtained when not distinguishing between sexes indicated that saprolegniosis lesions are mainly located above the lateral line and most frequently affect the dorsal cephalic region, the adipose fin, the peduncle and the caudal fin. However, differences were observed between males and females. Farmed trout presented a lower percentage of affected body surface (2.06 ± 4.36) and a lower number of lesions with and without necrosis because they received preventive treatment for saprolegniosis.     

Emissions of nitrous oxide from a constructed wetland using a groundfilter and macrophytes in waste-water purification of a dairy farm

 In less populated rural areas constructed wetlands with a groundfilter made out of the local soil mixed with peat and planted with common reed (Phragmites australis) are increasingly used to purify waste water. Particularly in the rhizosphere of the reed, nitrification and denitrification processes take place varying locally and temporally, and the question arises to what extent this type of waste-water treatment plant may contribute to the release of N₂O. In situ N₂O measurements were carried out in the two reed beds of the Friedelhausen dairy farm, Hesse, Germany, irrigated with the waste water from a cheese dairy and 70 local inhabitants (12 m³ waste water or 6 kg BOD₅ or 11 kg chemical O₂ demand (COD_Mn) day^–1). During November 1995 to March 1996, the release of N₂O was measured weekly at 1 m distances using eight open chambers and molecular-sieve traps to collect and absorb the emitted N₂O. Simultanously, the N₂O trapped in the soil, the soil temperature, as well as the concentrations of NH₄ ⁺-N, NO₃ ^–-N, NO₂ ^–-N, water-soluble C and the pH were determined at depths of 0–20, 20–40 and 40–60 cm. In the waste water from the in- and outflow the concentrations of COD_Mn, BOD₅, NH₄ ⁺-N, NO₃ ^–-N, NO₂ ^–-N, as well as the pH, were determined weekly. Highly varying amounts of N₂O were emitted at all measuring dates during the winter. Even at soil temperatures of –1.5  °C in 10 cm depth of soil or 2  °C at a depth of 50 cm, N₂O was released. The highest organic matter and N transformation rates were recorded in the upper 20 cm of soil and in the region closest to the outflow of the constructed wetland. Not until a freezing period of several weeks did the N₂O emissions drop drastically. During the period of decreasing temperatures less NO₃ ^–-N was formed in the soil, but the NH₄ ⁺-N concentrations increased. On average the constructed wetlands of Friedelhausen emitted about 15 mg N₂O-N inhabitant equivalent^–1 day^–1 during the winter period. Nitrification-denitrification processes rather than heterotrophic denitrification are assumed to be responsible for the N₂O production. Received: 28 October 1998     

东北地区芦苇营养器官比较解剖学研究

对黑龙江、吉林和辽宁不同生境芦苇的不定根、根状茎、茎、叶鞘、叶片等营养器官进行了解剖学研究。结果表明:不同地理分布和生态环境对芦苇营养器官的解剖结构产生了一定影响。营养器官均有发达的通气组织。根状茎与茎中均具有纤维层和机械组织带,鸭绿江口滨海湿地降雨量较多,鸭绿江口滨海湿地芦苇的纤维层和机械组织带明显少于三江平原和松嫩平原芦苇,而后二者的差异不显著。随着降雨量的增加,根状茎和茎中维管束数目、导管直径和维管束直径大体均呈上升趋势。叶片厚度有显著差异,而叶肉细胞层数未见显著变化。     

人为补水对扎龙芦苇湿地甲烷排放的影响

为研究人为补水对芦苇湿地甲烷排放的影响,分别在补水前5 d、补水后10、20和30 d测定了扎龙芦苇湿地淹水区RH和未淹水区RA的甲烷排放通量。结果表明,补水后30 d RH水深由20 cm上升至120 cm,甲烷排放通量由3.13 mg/(m2·h)增至9.60 mg/(m2·h),是对照组CH的1.62倍;RA在补水后30 d水深达到10 cm,甲烷排放通量由2.80 mg/(m2·h)上升至18.96 mg/(m2·h),为对照组CA的5.31倍。补水期间,RH的水深增加刺激了芦苇生长,从而为甲烷产生提供了更多底物,并增强了厌氧条件,导致甲烷排放增大;RA淹水后,大量有机质分解为甲烷产生提供了碳源以及通气状况的改变是促进其甲烷大量排放的原因。研究表明人为补水过程促进了淹水区和非淹水区的甲烷排放,建议在评估湿地甲烷排放时应考虑人为补水因素。     

莫莫格湿地不同盐分梯度对芦苇生理生态的影响

为探讨莫莫格湿地盐碱条件对芦苇生理生态特征的影响,于2010年在芦苇生长旺盛期,对不同盐分样地芦苇主要生理生态特征进行调查测量,包括株高、株数、生物量、盖度、芦苇叶片叶绿素含量和叶绿素荧光特征。结果表明,中等盐度(Na+含量在80.388mg/L)样地芦苇的株高和生物量等指标均高于低盐度(31.894mg/L Na+)或者较高盐度(258.490mg/L Na+)样地芦苇。而Na+含量在258mg/L时,样地芦苇的株高和生物量等明显低于中低盐度样地,说明较高盐度显著抑制芦苇的生长。Na+含量在258mg/L时,样地芦苇叶绿素含量和最大光化学效率(Fv/Fm)最高,表明此含盐量对芦苇叶绿素含量和光化学效率可能具有小幅促进作用,以减少盐碱胁迫对芦苇的伤害,这可能是芦苇长期适应盐碱胁迫的响应机制。     

三江平原芦苇营养器官的生态解剖学研究

从生态学角度对三江平原芦苇的营养器官进行了解剖学研究。芦苇的不定根、根状茎、茎和叶的解剖结构表现出了对水生和湿生环境的适应性。不定根的外皮层产生一层纤维细胞层，具发达的通气组织；根状茎中维管束散生。呈三环分布在基本组织中，薄壁组织细胞贮存有淀粉粒；根状茎和茎中均具发达的髓腔和通气组织；叶为等面型叶，机械组织发达。     

溶壁酶体外抗同丝水霉活性研究

为探究溶壁酶对水产动物水霉病的预防和治疗效果,以同丝水霉(Saprolegnia monoica)为研究对象,溶壁酶设0、5、10、20、40、80 mg/m L共计6个浓度处理组,取浓度为103个/m L的水霉孢子菌悬液0.1 m L,涂布于不同溶壁酶浓度的马铃薯葡萄糖琼脂培养基(PDA)上,25℃培养5 d,以最低抑菌浓度为判定指标,研究溶壁酶溶解同丝水霉孢子的抑菌活性;在此基础上,以溶壁酶最低抑菌浓度30℃分别水浴2 h和4 h处理同丝水霉菌丝块,PDA培养基上25℃培养5 d,通过用体外抑菌试验、菌丝显微结构观察等方法,研究溶壁酶最低抑菌浓度对同丝水霉菌丝的抑菌活性,为进一步开发水产动物抗真菌(替代孔雀石绿)药物提供科学依据。结果显示,溶壁酶对同丝水霉孢子的最低抑菌浓度为20 mg/m L,通过间隔添加溶壁酶该浓度,72 h能够有效抑制同丝水霉菌丝的生长;溶壁酶30℃水浴处理同丝水霉菌丝块的时间(2 h和4 h)与溶壁酶溶解菌丝效果呈正相关。     

Dose-Confirmation of Copper Sulfate for Treating Fungus on Channel Catfish,Ictalurus punctatus,Eggs at a Commercial Hatchery

This study at a commercial hatchery was required by the U.S. Food and Drug Administration to provide independent substantiation of the results of previous laboratory dose-confirmation studies on the use of copper sulfate (CuSO₄) to control fungus (Saprolegnia spp.) on the eggs of channel catfish, Ictalurus punctatus. The study compared an untreated control group of eggs to eggs treated with 10 mg/L CuSO₄ in a flow-through system; mean water temperature was 23.5°C. Eggs were treated once daily until the embryos reached the eyed stage (5 treatments). Hatching was complete by day 11, and fry were counted to determine the percentage of survival in each treatment. Fungus was identified by polymerase chain reaction (PCR) as Saprolegnia spp. The mean survival in the control treatments was 4% and 40% in the CuSO₄ treatments; the latter survival was significantly higher, but still lower than normal. This study confirms that 10 mg/L CuSO₄ is an effective treatment to control fungus on catfish eggs when used daily until the eggs are eyed. However, continued treatment of eggs until hatching occurs may be warranted based on fungal growth rates observed after treatments were discontinued.     

北镇新立湖湿地水深对芦苇香蒲共生关系影响的研究

芦苇和香蒲为辽宁省湿地1.0 m水深浅水区域优势物种,研究其共生关系对湿地保护与恢复具有重要意义。该文以北镇新立湖湿地内的芦苇和香蒲作为对象,通过对93个样方调查,分析不同水深对芦苇和香蒲生长及对其共生关系的影响。结果表明:水深显著影响芦苇和香蒲的生长,且对芦苇的影响大于对香蒲的影响。两种水生植物在共生竞争时均采用逃避策略,芦苇趋于向浅水区扩展,香蒲趋于向深水区扩展。     

组合植物型人工浮岛连续净化生活污水研究

[目的]研究由美人蕉（Canna indica）、芦苇（Phragmites australis）和石菖蒲（Acorus gramineus）组成的组合植物型人工浮岛对生活污水在动态条件下的净化效果。[方法]总氮（TN）含量采用过硫酸钾氧化-紫外分光光度法测定;总磷（TP）含量采用钼锑抗分光光度法测定;化学需氧量（CODCr）采用重铬酸钾法测定;pH值采用PHS-3C精密pH计测定。[结果]当水力停留时间（HRT）为11 d时,进水不稀释情况下,系统对CODCr、TN、TP的去除率分别为59.8%、46.4%、86.3%;在进水稀释1倍情况下,系统对CODCr、TN、TP的去除率分别为78.0%、71.0%、90.8%。[结论]由于植物之间的相互作用,人工浮岛的净化效果得到提高,组合植物型人工浮岛对生活污水的处理有广阔应用前景。