Journal of Aquatic Ecology

The study of spatial and temporal variability of distribution of phytoplankton communities in Northern part of the Persian Gulf (Qeshm andLengeh Islands) was studied. In this study, five groups (47 genera) of phytoplankton include Bacillariophyceae, Dinophyceae, Cyanophyceae, Crysophyceae and Euglenophyceae were identified. The results showed that Diatoms group (79.6 %) and Rhizosolenia genus (45.5 %), contributed more towards the percentage composition of different groups and genera of phytoplankton during the study. The annual changes in relative abundance and Margalef, Shannon, pielu and simpson indices were estimated, 0.58-2.56 , 0.08-0.97, 0.23-2.6, 0.09-0.93 respectively. Multivariate analysis of variance showed that during the sudy, density and biological indicators of phytoplankton were significant between seasons (P<0.05). The spatial cluster analysis based on similarity coefficients obtained twoclustersin theareasstudied. The results of the current study suggested that the ​​ecological conditions ofboth Islandsin ranks are instead moderate. Moreover, Phytoplankton of diversity and richness is good.