PCA and CCA analysis based on primary elements and phytoplankton of Moon Lake in Wuhan

In comparison with the water in the Qintai reach of the Hanjiang River,the primary elements and community of diatom and cyanobacteria in both the river and the Moon Lake in Wuhan were investigated from January through December 2007 and their relationships were explored by principal component analysis(PCA)and canonical correspondence analysis(CCA)analysis.The results indicate that 28 kinds of dissolved ions were detected in the Moon Lake and 27 ions in the Qintai reach over the whole-year monitoring.The PCA showed that P,As,Fe,Cu and Mn hold large cumulative contribution rates in the Moon Lake,while Si,Sb,Cd,V,Ba,Ag,and Mo in the Qintai reach.Moreover,the density of cyanobacteria was higher than that of diatom in Moon Lake,while diatom was more abundant than cyanobacteria in the Qintai reach.The CCA showed that the density of diatom in Moon Lake correlated positively with Se,Sr,Ag,Ba and Al,and cyanobacteria correlated positively with P,Cu,Cr and negatively with Mg,Ni,Ca,Zn and S.Using the same method (CCA),the density of diatom in the Qintai reach correlated negatively with Pb,B,As,Cr,Zn,Al,Cu,Mn,Fe and P and positively with Mo,Ca,Co,V,Sr,Ag,and the cyanobacteria negatively with Na,S,Mg,Ni,and K.The results indicated that Moon Lake lacked in DSi.At the same time,diatom promoted the adsorption capacity of other ions,e.g.Se,Sr,Ag,Ba,and Al,which probably took an alternative role for DSi(dissolved silicon).The combination of various dissolved ions was probably one of main driving forces for the succession of phytoplankton community in the Moon Lake.