Seasonal variations of periphytic diatom community in artificial substrata in Huizhou section of the Dongjiang River, Guangdong Province, Southern China

Although diatom has been widely used in biological or ecological monitoring of rivers,there is little information on diatom communities in most of Chinese rivers.In this study,we reported periphytic diatoms on artificial substrata(tile)in the Huizhou section of the Dongjiang River.We analyzed seasonal variations of the species composition and the relationship between the relative abundance and seasonal environmental factors at five sampling stations in 2010.A total of 153 periphytic diatom species,belonging to 40 genera,were identified.Dominant genera included Achnanthidium,Gomphonema,Melosira,Navicula,Nitzschia and Synedra.Gomphonema parvulum and Nitzschia palea were the common species in all the sampling sites with relative abundance1%.However,the relative abundance of the two species varied largely in seasons.Chl.a concentrations of the periphytic algae were positively correlated with the temperature.Redundancy analysis showed that water temperature,DO,NH+4-N,PO3-4-P,conductivity and pH were the major factors influencing the community structure of periphytic diatoms.Furthermore,hydrographic condition was crucial to some mobile species such as Nitzschia palea,whose relative abundance was low in summer mainly due to flushing in flood season.