山西平陆越冬大天鹅日间行为模式

2011年12月至2012年2月和2012年11月至2013年1月,采用瞬时扫描法,对山西平陆黄河湿地越冬的大天鹅进行了日间行为时间分配和活动节律的研究。结果表明,大天鹅在越冬期的主要行为是静息、运动和取食,分别占全部行为比例的(40.5±1.4)%、(22.8±0.9)%和(18.2±0.8)%。在日间节律方面,大天鹅的取食行为呈现早晚双高峰,静息行为的高峰则出现在早上和中午。对不同地点的大天鹅的行为时间分配研究表明,大天鹅在两地的行为时间分配存在明显差异。其中,在干扰强度较大的三湾村,运动和争斗行为更多;在干扰较小的关家窝村,静息和警戒行为更多。在行为时间分配与温度变化关系的研究中,通过Pearson相关性分析发现,大天鹅的取食、运动和理羽行为与温度成显著正相关,静息和警戒行为与温度呈现显著负相关。     

The role of herbivorous water birds in aquatic systems through interactions with aquatic macrophytes,with special reference to the Bewick’s Swan – Fennel Pondweed system

The role of aquatic macrophytes in stimulating biodiversity and maintaining clear waters is currently undisputed. The management of (eutrophic) shallow waters is therefore often directed at (re-)establishing macrophyte domination. In contrast, the role of water birds has long been considered of minor importance for the functioning of fresh water ecosystems. Indeed, in terms of biomass and production, water birds constitute only a minor part of these systems. However, water birds may graze heavily on water plants under certain circumstances, and the question arises whether herbivorous water birds have an important indirect effect on shallow fresh water systems. Mainly illustrated with the interaction between Bewick’s Swans and Fennel Pondweed, we present data on the role that water plants may play in the life of water birds and how water birds may impact water plants’ fitness in terms of survival, production, dispersal and competitive ability. It appears that water plants may be crucial for water birds during periods of high-energy requirements, such as migration. Despite the plants’ costs associated with water bird grazing, the interaction between water birds and water plants varies in nature from an apparent predator–prey relationship to a mutually beneficial interaction depending on the context and the perspective. For the case of the Bewick’s Swan–Fennel Pondweed interaction, regular bird grazing is sustainable and may actually favour the plant’s dispersal. Thus, Bewick’s Swans themselves may in fact play a crucial role in establishing and maintaining the Fennel Pondweed rich staging sites between the swans’ wintering and breeding grounds, which are vital for the swans’ successful migration.     

Avian influenza, migratory birds and emerging zoonoses: Unusual viral RNA, enteropathogens and Cryptosporidium in poultry litter

The last decade has witnessed the emergence of several new viral infectious agents, most notably avian influenza H5N1, SARS and West Nile Virus. The emergence of these agents is heavily associated with zonotic animal hosts, as well as migratory pathways of infected bird vectors. The environmental survival and persistence of nucleic acid associated with these viral agents may be important for both the detection as well as the occurrence of related diseases. Our hypothesis suggests that nucleic acid from such emerging viruses may enter into a virus-parasite surrogate relationship to aid in viral persistence. We suggest that Cryptosporidium and other gastrointestinal parasites, including Giardia, could be a) a reservoir of genetic material and a environment where assortment between that genetic variation can occur and, b) a source of zoonoses through infection of the ‘target’ animal (including humans). One example which illustrates this may be the uptake dsRNA from rotavirus into cryptosporidial oocysts, as this parasite has previously been shown to contain dsRNA viral-like particles. The importance of such a surrogate relationship is discussed and its implications for human and animal health highlighted.     

Satellite‐tracking of Northern Pintail Anas acuta during outbreaks of the H5N1 virus in Japan: implications for virus spread

We fitted Northern Pintail Anas acuta in Japan with satellite transmitters and monitored their spring migration movements relative to locations where the highly pathogenic H5N1 avian influenza virus was detected in Whooper Swans Cygnus cygnus in 2008. Pintails were assumed not to be infected with the H5N1 virus at the time they were marked because capture occurred between 2 and 5 months before reported outbreaks of the virus in Japan. We assessed spatial and temporal overlap between marked birds and occurrence of the virus and tracked Pintails after they departed outbreak locations. Eight of 66 (12.1%) Northern Pintails marked with satellite transmitters used wetlands in Japan where the H5N1 virus was detected in Whooper Swans. Apparent survival did not differ between Pintails that used H5N1 sites and those that did not. However, the proportion of Pintails that migrated from Japan was significantly lower among birds that used H5N1 sites compared with those that did not (0.50 vs. 0.79). Northern Pintails were present at the H5N1 sites from 1 to 88 days, with five birds present at the sites from 0 to 7 days prior to detection of the virus in Swans. The six Pintails observed to depart H5N1 sites did so within 2–77 days of the reported outbreaks and moved between 6 and 1200 km within 4 days of departure. Four Pintails migrated to eastern Russia. After their departure from outbreak sites, Northern Pintails made long‐distance migrations within the period when newly infected ducks would shed the H5N1 virus. This supports a hypothesized mechanism by which a highly pathogenic avian influenza virus could be spread by migratory birds.     

Fish assemblage changes relative to environmental factors and time in the Warta River, Poland, and its oxbow lakes

Four oxbow lakes and two neighbouring sections of their parent Warta River (Odra River system, Poland) were sampled to investigate differences in fish assemblages between habitats in 1999–2000. Additional comparisons were made with 12 other oxbow lakes in this section of the river that were sampled 30–40 years ago. Downstream of a man‐made reservoir, higher species number, diversity and evenness were recorded in oxbow lakes than in the river channel. Upstream of the reservoir, differences in these variables from both habitats were insignificant. Fluvial and stagnant water samples were clearly separated in the multivariate space of a detrended correspondence analysis (DCA). For two oxbow lakes and two neighbouring sections of the Warta River, 12 abiotic and biotic environmental variables were available, and only velocity, water temperature and conductivity were significantly correlated with canonical correspondence analysis (CCA) axes. Fish assemblages of four recently investigated oxbow lakes were clearly separated in the multivariate space of DCA from other neighbouring oxbows sampled 30–40 years ago. Species previously subdominant were becoming rare. Oxbow lakes that are continuously or at least periodically connected with the channel are indispensable for maintaining high biodiversity and a sustainable fishery in the river system.     

Isolation,Identification and Efficacy of Inorganic Phosphate-Solubilizing Bacteria from Oxbow Lakes of West Bengal,India

Microbial mobilization of sediment calcium-bound P constitutes an important process of P cycling in aquatic environments. The present study was conducted to identify the bacterial community responsible for inorganic phosphate solubilization in tropical oxbow lakes. Fifty eight phosphate-solubilizing bacteria were isolated from bottom soil, water, and fish gut and examined for solubilization of tricalcium phosphate. Results revealed aquatic PSB to be low-to-moderately capable in P solubilization (mean: 33.5 mg P L^?1; range: 6.3–68.8 mg P L^?1), and bacteria from wetland sediment and water were more effective than those from fish gut. The PSB were identified to belong to diverse genera, viz. Bacillus, Brevibacillus, Enterobacter, Agrobacterium, Pseudomonas, Acinetobacter, Microbacterium, Curtobacterium, Stenotrophomonas and Novosphingobium. The findings help in understanding the microbial role in inorganic P solubilization and identifying important P solubilizers in freshwater environments.     

新疆巴音布鲁克繁殖期大天鹅的生境选择

2011年和2012年的6-8月,考察了分布于巴音布鲁克自然保护区的大天鹅(Cygnus cygnus)种群,分析了大天鹅巢址选择特征和育雏期生境选择特征。在野外共记录到了26个大天鹅巢址。与对照样方比较发现,植被高度、水深、所在水域面积、距干扰源距离和安全等级存在显著差异。进一步逻辑斯蒂回归分析表明,植被高度、水深和安全等级是影响大天鹅巢址选择的最主要的3种生境因子。采用样线法对育雏期大天鹅的生境选择进行了调查,发现大天鹅对沼泽湿地表现出正选择性,对草地表现出负选择性。样方法调查中,利用样方与对照样方比较发现,9种生境因子均存在显著差异,逻辑斯蒂回归分析表明,距干扰源距离和安全等级是影响大天鹅育雏期生境选择的最重要的两种因子。这样的选择机制有利于大天鹅更好的躲避敌害,顺利完成孵化和育雏工作。     

老江河故道四大家鱼天然资源库研究

扼要介绍了老江河故道四大家鱼天然资源库的结构,并根据老江河故道水域生态系统的结构和功能特点,提出了四大家鱼的放养量应在重视种质质量的基础上,合理调控其放养结构和密度,此外文中还就保护和合理利用长江四大家鱼种质资源的有效途径以及维持老江河四大家鱼天然资源库健康运行的关键进行了分析探讨。     

Humic substance mineralization in a tropical oxbow lake (São Paulo,Brazil)

We evaluated the mineralization rates of humic substances in Infernão oxbow lake (State of São Paulo, Brazil). Experiments were conducted under aerobic and anaerobic conditions using fulvic acid and humic acid from four sources: Scirpus cubensis and Cabomba piauhyensis leachate submitted to a 120-day degradation process, sediment, and dissolved organic matter from the lake water. A fixed amount of substrate was added to 450 ml of water from Infernão lake, filtered over glass wool. After adding substrate, the flasks were incubated at 21.0°C under aerobic and anaerobic conditions. The dissolved organic carbon was monitored during 95 days. The results were fitted to first-order kinetics model, which pointed to one labile and one refractory fraction. The refractory fractions predominated, ranging from 71.4 to 84.3% for fulvic acid and from 73.4 to 85.0% for humic acid. Mineralization rates of the labile fractions of dissolved organic carbon were higher under aerobic than anaerobic conditions, while the converse was true for the refractory fractions.