Environmental abundance and microcystin-LR production ability of toxic Microcystis in Nanquan region of Lake Taihu

The variations of environmental abundance and microcystin-LR （MC-LR） production ability of toxic Microcystis in the Nanquan region of Lake Taihu are investigated by real-time quantitative PCR （RTQ-PCR） and high performance liquid chromatography （HPLC） from May to December in 2009. Simultaneously, degrees of water pollution and eutrophication are monitored. The results indicate that the water quality in the Nanquan region of Lake Taihu is in a moderate degree of pollution and eutrophication. Algal density exceeds the threshold of bloom from May to November. The environmental abundance of toxic Microcystis is more than 40% from May to October and then significantly declines to 5.66% due to the obvious reduction in the water temperature in December. From May to December, the MC-LR production ability of toxic Microcystis ranges from 1.661 to 9.293 μg/108cells. With the significant drops in water temperature and algal density, the MC-LR production ability of toxic Microcystis is obviously increased from November to December. It is concluded that the lake presents Microcystis bloom and the toxic Microcystis becomes dominant during most of the year. The environmental abundance and the MC-LR production ability of toxic Microcystis have a close relationship with water temperature. The effective control of toxic Microcystis should be considered in both the bloom period and the non-bloom period of winter since the MC-LR production ability of toxic Microcystis obviously increases in winter.

Spatial distribution and abundance of small fishes in Xiaosihai Lake,a shallow lake along the Changjiang (Yangtze) River, China

Spatial distribution and abundance of small fishes were studied in autumn 2007 in the Xiaosihai Lake, a shallow lake along the middle reach of the Changjiang （Yangtze） River. Based on the plant cover, the lake was divided into three major habitats： Myriophyllum spicaturn habitat （MS habitat）, Trapa bispinosa habitat （TB habitat）, and non-vegetation habitat （NV habitat）. A modified pop-net was used for quantitative sampling of small fishes in the three habitats, and the Zippin＇s removal method was used for estimating densities of the small fishes. A total of 13 species belonging to 5 families were collected, with 11 species in MS habitat, 7 species in TB habitat, and 5 species in NV habitat. Habitat type had significant effect on the spatial distribution of small fishes. The Shannon-Wiener diversity index in the MS, TB and NV habitats were 1.28, 0.56 and 0.54, respectively. The total density and biomass of small fishes were significantly higher in the MS habitat （13.68 ind/m^2 and 4.44 g/m^2） than in the TB habitat （1.41 ind/m^2 and 0.54 g/m^2） and the NV habitat （1.08 ind/m^2 and 0.40 g/m^2）, and were not significantly different between the TB habitat and the NV habitat. Water depth had no significant effect on spatial distribution of the small fishes. It was suggested that vegetation type played an important role in habitat selectivity of small fishes, and the presence of submersed vegetation should be of significance in the conservation of small fish diversity.

Intentional introduction of Artemia sinica(Anostraca) in the high-altitude Tibetan lake Dangxiong Co:the new population and consequences for the environment and for humans

The imbalance between supply and demand of Artemia cysts in China and around the world is increasing now.Salt lakes in Tibet may contribute to the solution of the problem.In Northern Tibet there are 26 saline lakes whose salinity and temperature may support Artemia survival at an altitude of 4 000–5 100 m.We found Artemia in 15 of these lakes.The saline lakes with Artemia populations mainly belong to the shallow basin lakes,and the majority of these lakes are small in area.The total area of lakes without Artemia is more than 1 000 km 2.Lake Dangxiong Co(Co means lake in Tibet) was chosen for the intentional introduction of Artemia sinica.In 2004,850 g of A.sinica cysts,originating from Qinghai,were introduced in the lake.Surveys in 2006–2014 showed that the average abundance of Artemia adults in the lake gradually increased from 20 ind./m 3 in 2006 to 1950 ind./m 3 in 2013.We assume that two subpopulations of A.sinica,separated by depth,may exist in the lake.The new Artemia population caused an increase in the number of species of phytoplankton and heterotrophic protozoa with a decrease of their total abundance.Water transparency also increased.Dominance in phytoplankton passed from cyanobacteria to diatoms.Changes occurred not only in the lake ecosystem;the number of water birds using the lakes also dramatically increased.Preliminary calculations showed that is it possible to harvest at least about 150 t cysts per year from the lake as well as 3.2 thousand tons of frozen or 350 t of dried biomass of adult Artemia.

Comparative study of epiphytic algal communities on Typha latifolia L.and Phragmites australis(Cav.)Trin.ex Steud in the shallow Gala Lake(European Part of Turkey)

The aim of this study was to determine the species composition, biodiversity and, relative abundance of epiphytic algae and their relationship with environmental variables on Typha latifolia and Phragmites australis at Lake Gala(National Park). Epiphytic algae were gathered monthly by collecting aquatic plants between March 2014 and November 2014. In the epiphytic flora were a total of 133 taxa were identified, 107 taxa were identified on T. latifolia and 96 were discovered on P. australis. While the mean species richness, species diversity and evenness values of the algae identified on T. latifolia were 46, 1.85 and 0.51 respectively, these values were respectively 43, 1.51 and 0.43 on P. australis. While diatoms were generally dominant, other dominant groups in the epiphytic flora included green algae and blue-green algae. The algae that had the highest relative biovolume on T. latifolia were Spirogyra affinis, Oscillatoria sancta and Gomphonema acuminatum, while the algae that had the highest relative biovolume on P. australis were E pithemia adnata, Oscillatoria sancta and R hopalodia gibba. Results show that species composition of epiphytic algae was different, but diversity values were similar on all the macrophytes. The hydrological pulse is one of the most important factors determining the physical and chemical environment of the epiphytic algal community. It was found that some environmental factors were highly eff ective on community distribution in the epiphyton. Additionally, it was observed that some epiphytic algae species had a substrate preference between T. latifolia and P. australis.

Research on Algae Removal by Ultrasonic and Jet Combined Process

Ultrasonic and jet combined process was studied to remove determined by static experiments, and stability of this combined process algae in lake type raw water. The optimum reaction time was was checked by dynamic experiments. The results was showed that ultrasonic/jet combined process has excellent removal efficiency on algae in lake type raw water, and it＇s a simple operation, and has no secondary pollution. When the pH, temperature, chlorophyll-a（Chl-a） and cell concentration（OD560） of raw water are 7.69, 25.8 ℃, 29.003 mg/m^3 and 0.091, the average removal efficiency on Chl-a and OD560 are 81.60% and 80.22%, respectively, which are stable by this combined process when it is operating in 36 hours, and samples are analyzed each 4 hours.

Seasonal dynamics of crustacean zooplankton community structure in Erhai Lake, a plateau lake, with reference to phytoplankton and environmental factors

The seasonal dynamics of a crustacean zooplankton community in Erhai Lake was investigated from May 2010 to April 2011. In total, 11 species were recorded, including six(6 genera) cladoceran and five(5 genera) copepod species. The crustacean zooplankton densities ranged from 24.3 to 155.4 ind./L. In winter and spring, the large-bodied cladoceran Daphnia galeata dominated the crustacean plankton community. In summer and autumn, when the colonial or filamentous algae dominated the phytoplankton communities, the small-bodied species(e.g. B osmina fatalis, Ceriodaphnia quadrangular, and Mesocyclops leuckarti) replaced the large-bodied ones. One-way ANOVA and redundancy analysis revealed that community structure was dependent upon total nitrogen, total phosphorus, water temperature, transparency, and the biomass of small algae. The variation in both phytoplankton structure and environmental variables were important factors in the seasonal succession of crustacean zooplankton structure in Erhai Lake.

Temporal changes in wetland plant communities with decades of cumulative water pollution in two plateau lakes in China's Yunnan Province

Abstract： Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 195os to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between chances in nlant communities and water nollution. InDianehi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 195os and 196os, were reduced to four types covering 2.4% by the late 2ooos. Alien plant communities started to appear in the lake in the late 197os, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 197os, declined to lo community types, covering 9.3% of the surface, by the late 2ooos. Alien plant communities appeared in the middle 198os, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively andpositively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.

Levels of Polychlorinated Biphenyls （PCB） in Fish from the Lakes of the Warmia and Mazury Region

The term polychlorinated biphenyls, or PCBs refers to a class of synthetic organic chemicals that are, to a large degree, chemically inert. PCBs are not found in a nature as a natural compounds and its appearance in natural environment is connected with unintentional and irresponsible human activity. PCBs have been produced on an industrial scale for more than 50 years and have been exported as chemicals in products to almost every country in the world. PCBs were commonly used as dielectric fluids in transformers and capacitors, in heat transfer and hydraulic systems. Other uses of PCBs included the formulation of lubricating and cutting oils, as plasticizers in paints. Nowadays PCBs are ranked among the compounds called POP （Persistent Organic Pollutants）. This group of hazard removable pollutants includes pesticides, dioxins and furans also. Fishes fished from August 2006 to December 2007 from lakes in north-east Poland： Lafiskie, Kisajno and Niegocin. The investigations were carried out on four fish species： roach, common bream, perch and pike. According to the preliminary mass and length measurements anticipatory treatment were realized. Subsequently fishes were analysed in accordance with National Institute of Hygiene method. According to the investigations results PCBs were found in fish muscular tissues, fished from north-east lakes. PCB level didn＇t exceed the highest acceptable daily dose （4pg-TEQ body mass/day）.