Plankton survey of Persian Gulf
was conducted Hormozgan, Bushehr and Khoozestan provinces during 4 seasons in 1998. In generally 244 species were Identified in Iranian area of Persian Gulf
that consisted of 124 species of Bacillarophyceae , 114 species of Dinophyceae , 5 species of Cyanophyceae , 1 species of Chrysophyceae and 1 species of Euglenophyceae . Result shows that the density and diversity of phytoplankton compare to last years (1976-1977) changed dramatically. The density of phytoplankton increased from east to west of Gulf and during the year was observed two major pike in late summer and late winter. Density
and diversity of phytoplankton in Koozestan region were more than other region. Seasonal average of phytoplankton in Hormozgan, Bushehr and Khoozestan were 1413622, 1440411 and 2237437 number /m3 respectively. Zooplankton had related inversely to phytoplankton where with increasing Zooplankton, decrease in phytoplankton was observed. Phytoplankton
density and diversity decrease profoundly changed slightly during years ago where the blue green algae had prevalent presence at all regions and the diatoms density decreased. Density
of phytoplankton increased from surface to depth zoom but decreased under
it, however at winter increase of phytoplankton was observed to depth 50 meter. . Statistical test shows that density of phytoplankton in different depths and regions has not significantly differences, also the seasonally density of phytoplankton had seasonally significantly differences too. Tuky test and clustering analysis shows that Shanon wiener diversity index at Khoozastan a Bushehr are significantly differences.