Study of habitat suitability of water fern (Azolla filiculoides, Lam.) in some aquatic ecosystems of Guilan and Mazandaran provinces using generalized linear model

Water fern (Azolla filiculoides) is one of the most dangerous invasive aquatic plant species in the temperate and tropical regions of the world. 4 different sites were selected in Guilan and Mazandaran provinces to examine the habitat suitability of Azolla. 15 physical, chemical and structural variables at each site were monthly sampled simultaneously with biological data (based on 24 presence instances and 24 absence instances of Azolla) during one year (2017-2018). The results of the Mann-Whitney test showed that except water and air temperature, ammonium and turbidity (p > 0.01 for all), a significant difference was observed between the presence and absence of Azolla and the remaining variables (p < 0.01 for all). The obtained results of the principal component analysis showed that water depth, phosphate and electric conductivity were the most influential factors in the first to third components, respectively so that they had the major effect on the habitat suitability of Azolla in the sampling sites. The results of generalized linear model showed that there was a significant difference between the presence and absence of Azolla in the sampling sites and all variables used in the principal component analysis (p < 0.01).