Study On The Structure Of Algae Community And The Relationships With The Physical-Chemical Factors In The Ponds Of Anodonta Woodiana And Carassius Auratus

The continuous and regular investigations on the algae community and water physical-chemical factors (e.g., temperature, pH, turbidity, transparency, dissolved oxygen) were conducted with a diet-feeding pond of Carassius auratus (N1R7), a high-density culture pond (N4R6) and a low-density culture pond (N1R3) of Anodonta woodiana in Nanquan Aquaculture Base of Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences from April 2013 to September,2014. The research includes:the algae community species composition in different types of aquaculture ponds, biomass, dominant species composition, community diversity and changes of the physical and chemical factors in water, etc. The results are as follows:A total of 72 algae species were identified after 12 monthly investigations from April 2013 to September,2014.43 species were Chrysophyta that were dominant among all species observed,14 species were Cyanophyta,11 species were Bacillariophyta,1 species was Dinophyta,1 species was Cryptophyta,1 species was Euglenophyta, and 1 species was Chrysophyta.In the research period, the results of algae biomass for each pond showed that the biomass in every pond maintains a higher level in summer and autumn, and a lower level in winter and spring. During the first six months, algae biomass in each pond showed an increasing trend, however during the later six months, the biomass of pond N1R3 showed a clearly decreasing trend. The similar situation could be observed in the pond of N1R7. In contrast, that in the pond N4R6 fluctuated up and down. The algae biomass in the three types of pond presented an order of N1R7> N4R6> N1R3 in the first half of the year, while in the second half of the year showed another order of N4R6> N1R7> N1R3. Additionly, the algae biomass kept an increasing trend over month, ranged from 2.02 × 106 to 27.20 × 106 cell/L. Furthermore, the biomass in all three ponds significantly and positively correlated with environment factors, especially, turbidity, temperature, and pH.Generally, the dominant species in each pond belonged to Cyanophyta, which also took the largest quantities in biomass. In the pond N1R7 the dominant species were Microcystis sp., Chroococcus sp., Scenedesmus sp., Anabeana sp.; those in the pond N4R6 were Microcystis sp., Chroococcus sp., Pediastrum sp., Spirulina sp., Scenedesmus sp., Oocystis sp., Cylindrospermopsis sp., Kirchneriella sp.; and those in the pond N1R3 were Microcystis sp., Chroococcus sp., Pediastrum sp., Chlorellaceae sp., and etc.The Shannon-Wiener diversity index ranged 0.50-2.59 in each pond in 12-month-period. The highest diversity index over the year was found in the pond N1R3 that even reached 2.65 in March, and the lowest index was noted in pond N1R3 that recorded as 0.50 in October.Diet-feeding in aquaculture pond could lead to water eutrophication and algae (especially Cyanobacteria) rapid proliferation. Culture density could obviously influence the structure of algae community and variation of water quality in the aquaculture ponds.