Research Journal of Environmental Sciences1819-34122151-8238Academic Journals Inc.10.3923/rjes.2009.504.513FathiA.A. Al-FredanM.A. YoussefA.M. 5200935Some characteristics of Lake Al-Asfar, Al-Hassa, Saudi Arabia were monitored over a period of one year. Seasonal differences in the quantitative and qualitative composition of the phytoplankton communities in Lake Al-Asfar were marked. The maximum crop density was recorded in spring, whereas lowest values occurred in winter. The total crop densities were mainly a reflection of the trends in counts of Chlorophyceae. Four algal groups were recorded during the investigation: Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae. Thirty nine species were identified allover the period of the investigation. Out of these, 14 species belong to Chlorophyceae, 15 belong to Bacillariophyceae, 7 to Cyanophyceae and 3 to Euglenophyceae. Chlorella sp., Chlorococcus humicola, Monoraphidium contortum, Oedogonium sp., Cyclotella meneghiniana, Gyrosigma sp., Fragilaria capucina,Navicula lanceolata, Surirella obonga, Synedra acus, Tabellaria sp. and Oscillatoria sp. were observed in a high rank of occurrence. Seven algal species were moderately common and 3 species were frequently recovered, most of them belong to Bacillariophyceae. The remaining recorded species were rarely recovered. Generally, the species data suggests that the water of Lake Al-Asfar can be considered as eutrophic.]]>Abdel-Satar, A.M. and A. Elewa,20012001pp: 136164Adams, V.D.,19911st Edn.,pp: 247pp: 247Mohammed, A.A., A.M. Ahmed and Z.A. Ahmed,19861799117Al-Fredan, M.A. and A.A. Fathi,20071032103214Al-Homaidan, A.A. and I.A. Arif,1998381525Al-Kahtani, M.A., A.M. Youssef and A.A. Fathi,20071040634068Allott, N.A.,198616145154Aly, M.M. and M.M. Yahya,20028487108Badawy, M.I., R.A. Wahaab and H.F. Abou Waly,199555258263Barber, G.H. and Y.E. Haworth,1981Vol. 44,pp: 112pp: 112Bourrelly, P.,19812nd Edn., Vol. II,pp: 517pp: 517Cole, G.A.,19833rd Edn.,pp: 401pp: 401El-Naggar, M.E., S.A. Shaaban-Dessouki, M.I. Abdel-Hamid and M.A. Elham,199720253276El-Naggar, M.E., S.A. Shaaban-Dessouki, M.I. Abdel-Hamid and E.M. Aly,199821183196El-Naghy, M.A., A.A. Fathi, A.M. El-Shahed and G.E. Garib,200415145172El-Wakeel, S.K. and S.D. Wahby,197067173200Fathi, A.A. and F.T. Zaki,19991299110Fathi A.A. and I.A. Kobbia,2000297791Fathi, A.A. and H.M. Abdelzahaher,20032003Fathi, A.A. and R.J. Flower,200567350362Fathi, A.A., H.M. Abdelzaher, R. Flower, M. Ramdani and M. Kraiem,200135303318Flower, R.J., S. Dobinson, M. Ramdani, M.M. Kraiem and C. Ben Hamza et al.,200135369388Fott, B.,1972pp: 116pp: 116Gharib, S.M. and A.M. Soliman,1998382544Goldman, C.R. and A.J. Horne,1983Pages: 464Pages: 464Goldman, C.R.,196030207270Golterman, H.L. and R.S. Clymo,1971pp: 166pp: 166Hobro, R. and E. Willen,197762605811Hussain, M.I., T.M. Khoja and M. Guerlesquin,1996333129137Hussein, A.B.,19891989Kobbia, I.M., R.M. Metwali and H.M. El-Adel,1995354557Komarek, J. and B. Fott,1983pp: 1044pp: 1044Krammer, K. and H. Lange-Bertalot,1986Pages: 876Pages: 876Krammer, K. and H. Lange-Bertalot,19881988Krammer, K. and H. Lange-Bertalot,19911991Krammer, K. and H. Lange-Bertalot,19911991Mohammed, A.A. and A.A. Fathy,199019141164Nosseir, M.A. and W.S. Abou El-Kheir,197061524Nygaard, G.,19787334Okla, S.M.,1987585561Pielou, E.C.,196613131144Prescott, G.W.,1987Pages: 293Pages: 293Ruttner, F.,1963pp: 307pp: 307Sabae, S.Z. and S.A. Rabeh,20004103116Talling, J.F., 19761976pp: 357-384pp: 357-384Shaaban, A.S., A.A. Badawi and A.A. E l-Awamry,198524733Shaikh, E.A., J.C. Roff and N.M. Dowidar,200492405416Smith, G.M.,19502nd Edn.,pp: 719pp: 719Staub, R., J.W. Appling, A.M. Hofstetter and I.J. Haas,197020905912Strickland, J.D.H. and T.R. Parsons,19722nd Edn.,pp: 327pp: 327Talling, J.F. and I.B. Talling,196550421463Utermohl, H.,19589138Whitton, B.A., T.M. Khoja and I.A. Arif,198613397106Willen, E.,197611265278