STUDY ON PYTOPLANKTON FYLA IN SOUTHERN CASPIAN SEA

The rapid change in nutrient status influences the phytoplankton community structure, and thus leads to the growing frequency and magnitude of nuisance. Therefore, the purpose of this work was to study phytoplankton of different seasons.For maturing of phytoplankton Factors, choose ٦ line Lisar, Anzaly, Sefidrood, Nooshahr, Babolsar and Amirabad that every line have ٤ stations(A, B, C, D) and water for analysis have taken from different deeps ( ٠,٥,١٠,٢٠,٥٠,١٠٠) meter in southern of Caspian sea and then transferred to laboratory of Caspian sea ecological institute. Then the samples transferred to laboratory of Ecological Academy, kept in cool and darkness in properly capped glass bottles. The phytoplankton was analyzed on a Nikon light microscope at ×٤٨٠ magnification. Algae abundance was determined using the Hydro bios counting chamber and sampled (volume ٠.١ ml). In this study, during ١٩٩٥-١٩٩٦ the overall average cell abundance of phytoplankton in different seasons were significant different. The dominant cell abundance was recorded by Chrysophyta (٧٩%) in winter. The maximum cell abundance and biomass of the other groups were between ٠% (Euglenophyta) to ٤٦% (Cyanobacter) respectively. The highest mean of phytoplankton abundance in during ٢٠٠٦-٢٠٠٧ was due to the existence of Chrysophyta, while the highest mean biomass was at spring due to the present of Pyrrophyta. The maximum average of cell abundance and biomass belonging to Chrysophyta and Pyrrophyta. During ٢٠٠٦-٢٠٠٧, cell abundance of Chrysophyta increased but Pyrrophyta show decrease of cell abundance. After M.leidyi arrival, Pyrrophyta and Cyanobacter show no significant changes.Since major changes in an ecosystem can affect all the tropic levels in the food chain, any ecological and environmental alteration can have a significant impact on phytoplankton species and the large-sized phytoplankton community in the Caspian Sea consisted of Chrysophyta, pyrrophyta and blue-green algae (Cyanobacter) in late summer.

کلیدواژه ها:

Phytoplankton ، Caspian Sea ، Season ، Abundance