Phytoplankton assemblage of a solar saltern in Port Fouad, Egypt

The present study is the first investigation of the phytoplankton community inone of Egypt's saltworks. The phytoplankton composition and distribution infive ponds of increasing salinity were investigated in the solar saltern of Port Fouad.The phytoplankton community consisted of 42 species belonging to cyanobacteria(16), diatoms (12), dinoflagellates (11), Euglenophyceae (2) and Chlorophyceae (1).The number of species decreased significantly and rapidly with increasing salinity,varying between 33 species in the first pond (P1) and one species in the crystallizerpond (P5). Conversely, the total phytoplankton density, except that recordedin P1, increased significantly with rising salinity, fluctuating between 8.7 and56 × 105 individuals l-1 in P2 and P5 respectively. In spiteof the local variations in climate and nutrient availability, the phytoplankton composition, density and spatialvariations along the salinity gradient were, in many respects, very similar towhat has been observed in other solar saltworks. The pond with the lowest salinity(P1 - < 52 g l-1) was characterized by a significant diversity andblooming of diatoms and dinoflagellates. Intermediate salinity ponds (P2 andP3) with salinity ～ 112-180 g l-1 exhibited a decline in bothspecies richness and density, but the stenohaline blue green algae (Synechocystis salina) did flourish. The highly saline concentrating ponds andcrystallizers (P4 and P5) with salinity ～ 223-340 g l-1 werecharacterized by few species, the disappearance of blue green algae and thethriving of the halotolerant green alga Dunaliella salina.