The Geographical Distribution Pattern,Community Structure And The Relationship With Environmental Factors Of Epiphytic Algae In China

Epiphytic algae is a group of algae that attached growing on the macrophytes.Epiphytic algae is an importent component of aquatic ecosystem which plays an important role in maintaining the function and stability of the aquatic ecosystems.There are still largely unknown of the community composition,species distribution and diversity pattern of epiphytic algae and their relationship with environmental factors.We surveyed 402 communities including the epiphytic algal,macrophyte and environmental factors in the major water bodys of China to studied the community composition,species distribution,geographical pattern of diversity,relationship between productivity and diversity of epiphytic algae and the effects of aquatic plants on epiphytic algae communities.In addition,a fixed point on a regular basis survey and experiment was conducted in Liangzi Lake to study the influence of submerged macrophytes community seasonal change on the epiphytic algal diversity.At last,a mesocosm experiment was conducted to elucidate vertical distribution pattern of periphyton and the effect of attached object structural complexity on periphyton.Based on the analysis of epiphytic algal communities in the country,the following conclusions could be drawn.(1)A total of 144 species belonging to 7 phyla,38 families and 71 genera were identified.Bacillariophyta,chlorophyta and cyanophyta were the main composition of epiphytic algae,and bacillariophyta was the dominant group.(2)The community composition of epiphytic algae was influenced by the composite effects of geography,climate,nutrition,water physicochemical factors and macrophytes.Geographical and climatic factors were with the most great explain on community composition of epiphytic algae,in which,latitude was the most great explain on epiphytic algal species and phylum composition.(3)The abundance and species richness of epiphytic algae had significant latitudinal,longitudinal and vertical latitudinal zonality in spatial distribution.The richness and abundance of epiphytic algae shown the first increasing then decreasing trends in the grandiance of latitude and altitude;the epiphytic algal richness shown the frist decreasing then increasing thrend in the grandiance of longitude,while,the abundance of epiphytic algae shown a decreasing trends in longitude grandiance.The effects of longitude,latitude and altitude on the epiphytic algal species richness were complex.They indirectly effected on epiphytic algal species richness by regulated the environmental factors,however.(4)The distribution of epiphytic algae was also with the traits of regional discrepancy.There were significant differences in the epiphytic algal community composition in different geographical distribution areas.The abundance of epiphytic alga was the highest in Northwest China and the lowest in Northeast China.The species richness was the highest in Northwest China and the lowest in Qinghai-Tibet plateau.(5)A unimodal of productivity–richness relationship for epiphytic algae was observed.At low productivity,habitat heterogeneity(coverage of aquatic plants)and available resources(light and temperature)driven the richness increasing with productivity.At high productivity levels,the epiphytic algae richness was decreased with increasing productivity on account of competitive exclusion.(6)The macrophyte characters was an important reason for the difference of epiphytic algal community composition on different macrophyte.High coverage and complex surface structure of macrophyte provided more heterogeneous habitats and created more niche for epiphytic algae that could accommodate more epiphytic algae and maintain high species diversity.The result of Liangzi Lake survey shown that Potamogeton crispus affected the richness of epiphytic algae by reducing nutrients concentrations(TOC,TN and COD decreased)and increasing transparency(Turb and SS decreased).This result suggests that high submerged macrophyte cover can improve the richness of the epiphytic algae community indirectly by changing water qualities.The simulated experiment indicated that periphyton preferred to distribute upper layer of water on account of the resource driven.Objects with complex surface structure provided more heterogeneous habitats and created more niche for periphyton that could accommodate more periphyton and maintain high species diversity.