Assessment of habitat suitability of watermilfoil (Myriophyllum spicatum L.) in some aquatic ecosystems of Mazandaran and Guilan provinces

6 different sites (4 sites situated in wetlands and 2 sites located in river) were selected in the Guilan and Mazandaran provinces to study the habitat suitability of Myriophyllum spicatum L. Monitoring of biotic data (36 presence and 36 absence data) was monthly carried out simultaneously with abiotic data (a set of physical, chemical and structural variables) during one year (from July 2017 to May 2018). Based on the results of Mann-Whitney, except water temperature, biological and chemical oxygen demand, ammonium and nitrite (p > 0.01), a significant difference was observed between the presence and absence of plant and the remaining of variables (p < 0.01). According to the results of principal component analysis (PCA), among 8 variables used in this method, flow velocity, total suspended solid and bicarbonate were the most important variables in the first three components, respectively so that they had the major effect on the habitat suitability of plant. According to the results of canonical correspondence analysis (CCA), the presence of plant in wetlands can be because of increasing of carbon dioxide, bicarbonate, dissolved oxygen and phosphate and the absence of plant can be attributed by increasing flow velocity, total suspended solid, electric conductivity and water depth while different seasons of year didn’t have much effect on the presence of absence of plant. Based on the results of the generalize linear model (GLM model), there was a significant difference between the presence and absence of plant and 8 variables (p < 0.01).