Effects Of Cipangopaludina Chinensis And Macrobrachium Nipponense Densities On Periphyton Communities

Periphyton can provide the basic energy through photosynthesis and purify water quality, it also provides attached matrix for benthic animals. Benthic animal is one of the important factors affecting periphyton, the different species and densities of benthic animals have different effects on the community structure of periphyton. In this article artificial substrate biofilm system had been established using biological fillers, the periphyton community structures and seasonal variation characteristics in Shihoudian lake were investigated from April to November in 2014. the effects of Cipangopaludina chinensis and Macrobrachium nipponense densities on periphyton communities and water quality were studied from April to July in 2015, so as to provide a theoretical basis for the biological control of the water ecosystem and the healthy aquaculture.1. The seasonal changes in periphyton community in the breeding area of Shihoudian lake. Seven phyla of periphyton were identified, there were 57 species of Bacillariophyta, accounting for 52%; 28 species of Chlorophyta, accounting for 52%; 9 species of Cyanophyta, accounting for 8%; 6 species of Euglenophyta, accounting for 6%; 5 species of Pyrrophyta, 3 species of Cryptophyta, 1 species of Chrysophyta. In the breeding area of Shihoudian, densities, chlorophyll a, organic matter and the primary productivity of periphyton in the middle water layer were higher than in upper and lower layers in summer, but in spring and autumn that in upper layer were higher than in middle and lower layers. Organic matter content in the whole year showed a sustained growth trend, the primary productivity showed a downward trend after reaching the peak in summer(August), listed on summer>autumn>spring. In August 6th, the Shannon-wiener index of biodiversity was the lowest, and Oscillatoria simplicissima showed significant dominance(p<0. 01). The dominant species of the community correlated with the water depth and temperature. The water temperature and dissolved oxygen were the key environmental factors in the growth of the periphyton in spring. In summer the primary productivity, chlorophyll a, and organic matter content of the periphyton were significantly positive correlated with the total nitrogen content(p<0. 05). The periphyton was negatively correlated with the nitrogen and phosphorus nutrient salts(p<0. 05) in autumn. Correlation analysis of periphyton and physicochemical factors showed that p H, content of nitrogen and phosphorus in Shihoudian lake could promote densities and organic matter accumulation of periphyton.2. Effects of densities of Cipangopaludina chinensis on periphyton community. Seven phyla of periphyton were identified in the control groups, there were 39 species of Chlorophyta, accounting for 60%; 18 species of Bacillariophyta, accounting for 28%; 5 species of Cryptophyta, accounting for 8%; 3 species of Cyanophyta, 3 species of Euglenophyta; 3 species of Pyrrophyta, 1 species of Chrysophyta. Seven phyla of periphyton were identified in Cipangopaludina chinensis experimental groups, there were 47 species of Chlorophyta, accounting for 54%; 26 species of Bacillariophyta, accounting for 30%; 4 species of Cryptophyta, accounting for 5%; 3 species of Cyanophyta, 3 species of Euglenophyta; 3 species of Pyrrophyta; 1 species of Chrysophyta. The species of Chlorophyta and Bacillariophyta were dominant in the structure of the periphyton communities in experimental groups and control groups. Chlorophyta cell numbers decreased, the organic matter content, chlorophyll a, and densities of periphyton increased with Cipangopaludina chinensis densities, but the densities and organic matter of periphyton in Cipangopaludina chinensis experimental groups were lower than the control groups. The biodiversity of the densities of 400 ind./m3 of Cipangopaludina chinensis in experimental groups was significantly higher than the control groups(p<0. 05). With Cipangopaludina chinensis densities, the total nitrogen and ammonia increased. The addition of Cipangopaludina chinensis had a certain role on the removal of total phosphorus content, the densities of 400 ind./m3 experimental groups had a best removal effect.3. Effects of densities of Macrobrachium nipponense on periphyton community. Seven phyla of periphyton were identified in the Macrobrachium nipponense experimental groups, there were 48 species of Chlorophyta, accounting for 55%; 26 species of Bacillariophyta, accounting for 30%; 4 species of Cryptophyta, accounting for 5%; 3 species of Cyanophyta, 3 species of Euglenophyta; 3 species of Pyrrophyta; 1 species of Chrysophyta. The species of Chlorophyta and Bacillariophyta were dominant in the structure of the periphyton communities in experimental groups and control groups. The greater densities Macrobrachium nipponense was, the higher cell number percentage Chlorophyta would be. At the late time, Cosmarium maximum in periphyton communities of the experimental groups showed a significant advantage(p<0. 01). The organic matter content and periphyton densities of control groups were lower than those in experimental groups. Periphyton chlorophyll a of experimental groups and the control groups showed a increasing trend. The periphyton chlorophyll a content of control groups was lower than that in the experimental groups, and 200 ind./m3 experimental groups made chlorophyll a content increase, promoted the growth of periphyton. The periphyton biodiversity of experimental groups decreased. The experimental groups of 200 ind./m3 could increase periphyton species diversity, and high densities increased the number ratio of Chlorophyta cells, reduced periphyton communities biodiversity. Total nitrogen, ammonia nitrogen and total phosphorus of experimental groups were higher than those in control groups, increased with the densities of Macrobrachium nipponense.