She also recorded high levels of nitrates and phosphates associated with high phytoplankton densities due to the abundance of Cylindrotheca closterium in this region. Although the salinity of the first pond (51.4 g l− 1) was higher than that previously recorded (38 g l− 1) in this region
of the Suez Canal in summer by Madkour (2007), nutrient concentrations were PLX4032 in vitro high (3.42 and 2.54 μmol l− 1 for nitrates and phosphates respectively), and the same as those previously recorded in the Suez Canal. These high nutrient values supported the high densities of some cosmopolitan species such as the diatom C. closterium and the dinoflagellates Karenia brevis and Scrippsiella trochoidea, which indicate continuity of Olaparib chemical structure eutrophic conditions. These blooming species in the first pond were reported as cosmopolitan species that inhabit the Mediterranean basin ( Gómez 2003), and C. closterium was found blooming in a Mediterranean
hypersaline coastal lagoon in summer ( Gilabert 2001). The diversity of phytoplankton in the second and third ponds exceeded the values recorded in coastal environments. This was obvious in the continuous predominance of diatoms, given the number of species in the second pond (P2), but their density was lower than that recorded in the first pond (P1). C. closterium, a versatile species occurring in most of the ponds that is considered to be a pollution indicator species ( Gaballah & Touliabah 2000), constituted the bulk of the diatom communities. Dinoflagellates were represented by a few stenohaline species
(e.g. Gymnodinium spp., some designated here as Karenia), whereas cyanobacteria did not have a great impact on either the number of species or their density. The abundances of diatoms and dinoflagellates decreased strongly in the third pond (P3), indicating the inability of these groups to withstand increasingly extreme living conditions as manifested by elevated salinity (179.5 g l− 1) and temperature (26.9 °C). However, it seems that these parameters are the major factors controlling their growth, Lck since nutrients were sufficient. Andersson et al. (1994) indicated that when nutrients are sufficient, both temperature and light intensity are the factors determining diatom growth. In contrast, it was found that the density of cyanobacteria (mostly Synechocystis salina, Leptolyngbya, Aphanothece clathrata, Synechococcus and Microcoleus sp.) increased significantly with salinity. Oren (2000) reviewed several studies on cyanobacteria in hypersaline environments and reported that dense communities of cyanobacteria are often a prominent feature of planktonic and benthic biota in high salinity concentration environments, including salterns. He concluded that many types of cyanobacteria of coccoid form (e.g. Aphanothece, Synechocystis and Synechococcus) and filamentous forms (e.g.