Effects of some environmental factors on the population density and species diversity of phytoplankton in Bitter Lakes, Egypt

摘要: The assessment of the phytoplankton community structure in Bitter Lakes during 2012–2013 indicated about 150 species belonging to 73 genera. These are classified as 89 diatoms, 27 dinoflagellates, 19 chlorophytes, 13 cyanophytes, and one euglenophytes well rare silicoflagellates. Diatoms were leading most dominant group forming 81.67 % total number individuals due high flourishing Rhizosolenia alata variety gracillima, Thalassionema nitzschioides, Skeletonema costatum, Thalassiothrix frauenfeldii, Chaetoceros lorenzianus. Abu-Rommanh was productive area counts, whereas Shandoura lowest one, coincided principally with types amounts pollutants highest human fishing activities at this Lakes. Seasonally, summer 2012 season an average 8464 unit/L followed by autumn 6199 unit/L. Whereas, winter spring 2013 observed approximately similar averages 5527 5194 unit/L, respectively. Analysis diversity that sustained good variations species. It fluctuated between 2.4 3.21 2012, which may reflect healthy state ecosystem stability autumn. results revealed density slightly increased from counts 6286 2002–2003 6346 present study, while significantly 108 study. This be relative increase eutrophication last 10 years. Generally, seasonal fluctuations positively correlated water temperature (22–24.2 °C), dissolved oxygen (4.85–11.11 mg/L), reactive nitrate (0.04–1.00 but it inversely ammonium (0.05–0.2 mg/L) silicate (0.10–1.44 mg/L). stepwise multiple regressions silicate, nitrate, effective factors controlled 2012–2013.