en Ecology Ecology پژوهشي Orginal research papers <p dir="ltr" style="text-align: justify;">The aim of this work was to be informed and aware of the red tide conditions before the entering of algal blooms in seawater supply canals of the shrimp farm and hatchery complexes in Bushehr Province. Field investigations and monthly samplings have been carried out to determine environmental parameters, nutrients, chlorophyll&ndash;a and phytoplankton in the southern part of the input water channels of Mond, Delvar and Heleh farmed shrimp complexes from April to December 2011. The identified phytoplankton belonged to three classes of <em>Bacillariophyceae</em>, <em>Dinophyceae</em> and <em>Cyanophyceae</em>. &nbsp;12 genera belonging to <em>Dinophyceae</em>, 25 genera to <em>Bacillariophyceae</em> and two genera to <em>Cyanophyceae</em> were observed during the study. The highest average density of total phytoplankton was recorded at Heleh station at 18374 cells/lit. The maximum density of phytoplankton was at Delvar station in December. The highest density of <em>Dinophyceae</em> was observed in August. <em>Alexandrium </em>sp<em>., Ornithocercus </em>and <em>Prorocentrum </em>sp. were the predominant species of<em> Dinophyceae</em> class. <em>Bacillariophyceaes</em> are thermo-tolerant and halo-tolerant while <em>Dinophyceaes</em> and <em>Cyanophyceaes</em> are thermo-intolerant and halo-intolerant. <em>Bacillariophyceaes</em> are silica limited while <em>Dinophyceaes</em> are phosphorus limited phytoplankton</p> Phytoplankton composition, Shrimp farm, Nutrients, Environmental parameters, Bushehr Province 1044 1054 http://jifro.ir/browse.php?a_code=A-10-1272-211&slc_lang=en&sid=1 Kh. Aein Jamshid khosrow.aein@gmail.com 100319475328460022496 100319475328460022496 Yes F. Mohsenizadeh 100319475328460022497 100319475328460022497 No S. Omidi 100319475328460022498 100319475328460022498 No