[[Catch composition of monofilament gillnet netting with different mesh sizes in Qingcaosha Reservoir, Shanghai, China].

During 2010 to 2012, fish diversity in Qingcaosha Reservoir was studied based on gillnets (multi-mesh monofilament gillnets and single-mesh trammel gillnets), electric fishing, bottom trawl and cage. The investigation collected a total of 34 fish species, belonging to 8 orders, 12 families. Cypriniformes contained the largest number of species (19 species) in the collection, followed by Perciformes (6 species). Multi-mesh monofilament gillnets sampled 19 fish species, of which Coilia nasus was the dominant species. Hierarchical cluster analysis indicated that mesh size of monofilament gillnets had significant influence on the composition of catches: C. nasus and Hemiculter bleekeri were the dominant species of catches of gillnet netting with mesh size of 2 cm, while C. nasus was the dominant species of catches of the nettings with mesh sizes larger than 2 cm. Species numbers and the catch per unit of effort ( CPUE) had a decreasing tendency with the increasing mesh size. Mesh size also had significant effects on the total length distribution of the dominant species C. nasus, which increased with the increasing mesh size. The results suggested that a combination of several gears was required to reliably estimate fish diversity of standing waters.

[Macrozoobenthos community structure and its indicative significance in water quality bioassessment of Fenshuijiang Reservoir, Zhejiang Province of East China].

A monthly investigation was conducted on the macrozoobenthos at 7 stations of Fenshuijiang Reservoir in Zhejiang Province of East China from November 2008 to October 2009. A total of 37 taxa were collected, most of which belonged to Oligocheata and Chironomidae. Limnodrilus hoffmeisteri was dominant in spring, summer and autumn, and Chironomus gr. plumosus was prevailing in winter. The collector-gatherer was the predominant group in species number, density and biomass. The mean annual density and biomass of the community were (488.0 +/- 48.8) ind X m(-2) and (1.86 +/- 0.49) g X m(-2), respectively. There were no significant differences in the macrozoobenthic density among the stations and in the macrozoobenthic biomass among the stations and among the seasons, but the macrozoobenthic density had a significant seasonal variation, with the sequence of spring > summer > winter > autumn. Water temperature and water depth were the main factors affecting the spatial distribution of the macrozoobenthos. Shannon index and Goodnight-Whitley index were not suitable for the assessment, whereas the Wright index, Carlander index, Pielou index and trophic level index showed that this reservoir was slightly polluted.

[Structure and function of Fenshuijiang Reservoir ecosystem based on the analysis with Ecopath model].

Based on the 2008-2009 survey data of fishery resources and eco-environment of Fenshuijiang Reservoir, a mass balance model for the Reservoir ecosystem was constructed by Ecopath with Ecosim software. The model was composed of 14 functional groups, including silver carp, bighead carp, Hemibarbus maculates, Cutler alburnus, Microlepis and other fishes, Oligochaeta, aquatic insect, zooplankton, phytoplankton, and organic detritus, etc. , being able to better simulate Fenshuijiang Reservoir ecosystem. In this ecosystem, there were five trophic levels (TLs), and the nutrient flow mainly occurred in the first three TLs. Grazing and detritus food chains were the main energy flows in the ecosystem, but the food web was simpler and susceptible to be disturbed by outer environment. The transfer efficiency at lower TLs was relatively low, indicating that the ecosystem had a lower capability in energy utilization, and the excessive stock of nutrients in the ecosystem could lead to eutrophication. The lower connectance index, system omnivory index, Finn' s cycled index, and Finn's mean path length demonstrated that the ecosystem was unstable, while the high ecosystem property indices such as Pp/R and Pp/B showed that the ecosystem was immature and highly productive. It was suggested that Fenshuijiang Reservoir was still a developing new reservoir ecosystem, with a very short history and comparatively high primary productivity.

[Phytoplankton community structure in Mingzhu Lake of Chongming Island, Shanghai].

A preliminary study was conducted on the phytoplankton community structure and the annual variation of species diversity in Mingzhu Lake of Chongming Island from January to December 2007. A total of 120 phytoplankton species belonging to 8 phyla and 63 genera were collected, among which, Phormidium tenue, Meismopedia tenuissima, M. convoluta, Microcystis incerta and Synedra ulna were the dominant species. The mean annual density and biomass of the phytoplankton were 5361.57 x 10(4) cell x L(-1) and 7.68 mg x L(-1) respectively. There was a significant difference in the monthly phytoplankton standing crop (P < 0.01) , being the highest in July, but no significant difference was observed among different observation stations. The Shannon index and Margalef index of the phytoplankton community were higher in spring and winter than in the summer and autumn. Biological evaluation indicated that the water quality of Mingzhu Lake was better in spring and winter than in the other two seasons, and canonical correlation analysis (CCA) suggested that the main factors affecting the phytoplankton community were water temperature, followed by total phosphorus, and total nitrogen.

[Structural characteristics of chironomid community and their indicative significance in bioassessment of water quality in Mingzhu Lake of Chongming Island, Shanghai].

The structural characteristics of chironomid (Diptera: Chironomidae) community in Mingzhu Lake of Chongming Island, Shanghai, China were studied from July 2006 to April 2008. A total of eleven chironomid species belonging to 10 genera and 3 subfamilies were collected, among which, Propsilocerus akamusi and Microchironomus sp. were predominant. Based on clustering analysis (CA) and importance value (IV), it was found that the dominant species shifted seasonally, with Microchironomus sp. in spring and summer, Tanypus chinensis in autumn, and P. akamusi in winter. There was a significant seasonal difference in the Shannon-Weaver diversity index (H') of the chironomid community, with the lowest in summer and higher in the other three seasons. The H' was significantly correlated with species richness (S) and evenness (J), and more strongly governed by J. The average density and biomass of the chironomid community were the highest in winter, with a minimum density in autumn and a lower biomass in the other seasons. Among the three dominant species, P. akamusi and Microchironomus sp. had more obvious seasonal fluctuations in their population dynamics than T. chinensis. Based on the bioassessment methods of water quality, e.g., H' and Hilsenhoff biotic index (BI), the Mingzhu Lake was considered to be moderately organically polluted and eutrophicated.