Relationship between Periphyton Distribution and Water Quality of Gufu River of Three Gorges Reservoir Area

Periphyton and water samples were collected ten times from Gufu River in Xingshan County,Hubei Province,from December 2010 to December 2011.A total of twenty-eight genera were identified from the periphyton samples,and twelve water quality parameters were tested.Factor analysis was performed on the twelve water quality factors,with four major components,whose eigenvalues were greater than 1,selected.The first major component was accounted by TN and NO₃^--N,the second by pH and COD_Cr,the third by PO₄^3--P,TP and NH₄⁺-N,and the fourth by Cond and TOC.The relationships between the nine extracted dominant water quality parameters and the main genera of periphyton were analyzed by CCA.According to CCA ordination,the sequencing of the correlations between the main water quality parameters and periphyton distribution was:COD_Cr>pH>TN>NO₃^--N>TOC>TP>PO₄^3--P>Cond>NH₄⁺-N.Monte Carlo significance test showed that the distribution of the periphyton taxa was most influenced by COD_Cr and pH,and less by TN,NO₃^--N and TOC.Both pH and COD_Cr were strongly negatively correlated with each other.Most of the periphyton taxa in Gufu River were strongly correlated with COD_Cr,while only Chaetophora was fit for the low COD_Cr and slightly alkaline environment.TN and NO₃^--N were strongly correlated,but both of them were negatively correlated with TOC.These three factors roughly classified the periphyton into two ecological groups:one preferring nitrogen,and the other carbon.Though usually a limited nutrient factor for algae,TP was not a dominant influencer on the distribution of periphyton in Gufu River.