S. Bagheri - Expert
S. Khatib - Expert
J. Sabkara - Expert
Y. Zahmatkesh - Expert

This study focuses on density and species composition of phytoplankton during bloom in the southwestern Caspian Sea off Anzali. The eighteen sampls were took  between Apri and July ۲۰۲۱. The findings displayed, the  phytoplankton bloom speices was distanguited in the study as cyanobacteria Nodularia spumigena  Mertens as bloom in the southwestern Caspian Sea in ۲۰۰۵. A total of ۸  phytoplankton species were distinguished during the bloom, the phytoplankton abundance were calculated  as ۸,۶۴۰,۰۰۰ cells.l-۱. Contributions of cyanophyta (۵,۷۲۰,۰۰۰ cells. l-۱) to total phytoplankton were higher than any other group. The cyanobacteria Nodularia spumigena abundance as ۵۱۲,۰۰۰,۰۰۰ cells.l-۱ provided the biggest contributions to the total phytoplankton during the bloom. Vertical distribution of  N. spumigena at the bloom region revealed that most N. spumigena abundance occurred in the upper layer (۰-۵ m) almost ۵,۰۰۰,۰۰۰ cells.l-۱. After bloom period, the number of phytoplankton species increased sharply and identified ۱۸ species. Bacillariophyta were dominant (۶۰,۰۰۰ cells.l-۱). Cyanobacteria (۱۲,۶۰۰ cells.l-۱) were the second most important group, contributing to the total phytoplankton abundance. The phtytoplankton abundance was declined  sharply almost ۸۳,۴۰۰ cells.l-۱ after bloom as compared with bloom period. The total phosphorus and nitrogen consenterations rised sharply as ۰.۵۹  and ۹.۹۱ µM. l-۱ during bloom. There is strong relationship between N. spumigena abundance and environments factors. The very low wind, strong heating of the upper layer almost ۲۹ ºC and increasing of  nutrients levels were the most reasons of N. spumigena bloom in the southwestern Caspain Sea Anzali offshore.

Nodularia spumigena, Abundance, Taxa, Temperature, Wind, Off Anzali