Finally, sodium chloride (halite)

precipitates in crystallizer ponds at TDS ∼ 300–350 g l− 1 (Gongora et al. 2005). According to the duration of operation, BMS 354825 saltworks have been divided into continuous and seasonal. The first maintain a salinity gradient throughout their ponds and produce salt continuously during the entire year. The second maintain a salinity gradient and produce salt only during the summer (Davis 2000). Solar salterns are not just salt production plants; they also function as integrated saline wetlands of a unique coastal aquatic ecosystem that combines considerable environmental heterogeneity with a steep salinity gradient (Costa et al. 1996). The planktonic and benthic communities Enzalutamide price of marine organisms (e.g. bacteria, algae, copepods, molluscs, worms) that develop along with the increasing salinity gradient in the evaporating ponds and crystallizers of saltworks create a biological system that can help or harm salt production (Davis 1993). The development of planktonic species that are adapted to narrow salinity ranges aid salt production by colouring the water to improve solar energy absorption and water evaporation, as well as by creating and maintaining appropriate quantities of organic substances that power the entire biological system at the desired

level. Benthic communities seal ponds against water leakage and infiltration, permanently remove excess quantities of nitrogen and phosphate from the overlying water and maintain desired thicknesses in all ponds (Davis 2000). On the other hand, mats of unicellular cyanobacteria that exist in the brine sometimes

produce massive amounts of polysaccharide slime which adversely affects salt production process (Davis & Giordano 1996). Because of the importance of phytoplankton in salt PTK6 production, their community structure and distribution have been studied in several solar saltworks all over the world (Ayadi et al., 2004, Dolapsakis et al., 2005 and Chatchawan et al., 2011). Although there are many saltern ecosystems in Egypt, few studies have reported the community structure and ecological function of their biological system. Taher et al. (1995) was the only study that investigated the microbial mats in the sediments in the salina system of Port Fouad. The main objective of the present study was to provide new information on the composition and abundance of phytoplankton population in ponds of different salinity in a solar saltern in Port Fouad, Egypt. Species substitution with salinity gradient and the range of salt-tolerance of the different phytoplankton taxa was considered. The study was conducted in the solar saltern (El Nasr Salina Company) situated on the extreme north-eastern coast of Sinai (about 31°12′ to 31°14′N and 32°18′ to 32°20′E). It is an artificial system formed of interconnected ponds of different salinities, from that of seawater up to sodium chloride saturation.