Seasonal changes of phytoplanktons in the littoral waters of larak island (Persia Gulf)

In this investigation, the quantity and quality changes of phytoplanktons were seasonally studied in the littoral waters of Larak Island from October 2005 to September 2006. Nine stations were randomly selected in north-east, north and north – west of Larak Island. The samples were collected by phytoplankton net; fixed by formalin 4٪ and then were transferred to the laboratory ashore. In the laboratory 1cc subsample of each 100cc sample were studied under microscope for further identification and counting with the Rafter lame. The results indicated that, 51 genera of phytoplankton were totally identified of which 17 genera belong to phylum CHromophyta, class Dinophyceae and 1 genera belongs to class Chrysophyceae and 33 genera belong to Bacillariophyceae. Oscillatoria sp. and Anabaena sp. from phylum Cyanophyta, class Cyanophyceae were found in autumn and summer. Density of phytoplankton in winter were measured more than other seasons, meanwhile this value was the least in summer. According to one-way ANOVA analysis, it was revealed that there is a significant difference between diatoms density and dinoflgellate density, and ANOVA results showed that diatoms and dinoflagellate density in seasons were significantly different too. But there was no significant difference between stations from point of density value.