The effect of the Changjiang River on water regimes of its tributary Lake East Dongting

The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting （Lake ED） during a 35-year study period （1980-2014）. Specifically, we investigated Lake ED＇s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge abil- ity under different hydrologic conditions of the Changjiang River. The results show that （1） the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River＇s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. （2） Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.

Relationship between community type of wetland plants and site elevation on sandbars of the East Dongting Lake,China

Plant communities on sandbars were important, and restoration of degraded wetland were significant to biological conservation in the East Dongting Lake region. In this study, typical wetland community types on sandbars and their site elevation were surveyed to explore relationship between community distribution and site elevation. Results show that eight major communities in this region were wetland communities dominated by Juncus effusus, Carex brevicuspis, Polygonum hydropiper, Salix triandra, Oenanthe Javanica, Phalaris arundinacea, Miscanthus sacchariflorus and Phragmites communis respectively. These communities had obvious constructive species and companion species, while site elevation could affect community composition and their species diversity. On sandbars in the East Dongting Lake, vegetation was largely composed of hygrophytes companied with a few mesophytes. The higher the site elevation was, the nearer the site was to the water, and the lower community diversity became. Except soil humidity and site elevation, growth period of plants after inundation could also affect species richness in the communities.

Phylogenetic and Molecular Analysis of an H7N7 Avian Influenza Virus Isolated in East Dongting Lake in 2012

Objective In March 2012, an H7N7 subtype avian influenza virus （AIV） named A/wild goose/Dongting/PC0360/2022 （H7N7） （DT/PC0360） was recovered from a wild goose in East Dongting Lake. We performed whole-genome sequencing of the isolate, and analyzed the phylogenetic and molecular characterization. Methods RNA was extracted from environment samples （including fecal samples from wild bird or domestic ducks, and water samples） for detecting the presence of Influenza A Virus targeting Matrix gene, using realtime RT-PCR assay. The positive samples were performed virus isolation with embryonated eggs. The subtype of the isolates were identified by RT-PCR assay with the HI-HI6 and N1-N9 primer set. The whole-genome sequencing of isolates were performed. Phylogenetic and molecular characterizations of the eight genes of the isolates were analyzed. Results Our results suggested that all the eight gene segments of DT/PC0360 belonged to the Eurasian gene pool, and the HA gene were belonged to distinct sublineage with H7N9 AIV which caused outbreaks in China's Mainland in 2013. The hemagglutinin cleavage site of HA of DT/PC0360 showed characterization of low pathogenic avian influenza virus. Conclusion Strengthening the surveillance of AlVs of wild waterfowl and poultry in this region is vita for our knowledge of the ecology and mechanism of transmission to prevent an influenza pandemic.