Multivariate analysis of phytoplankton standing crop in western harbor of Alexandria [Egypt] during spring and summer

Quantitative collections of phytoplankton were performed in the western harbor during spring and summer 1989, which represent the extreme conditions of both temperature and salinity. Seventy four species were recorded, belonging to Bacillariophyceae [43], Dinophyceae [14], Chlorophyceae [10], Cyanophyceae [4], Euglenophyceae [2] and one Silicoflagellate. Although numerous species were encountered, yet very few of them formed the main bulk of the community; namely, Euglena acus, Cycotella meneghiniana, Nitzschia closterium in spring, and Prorocentrum micans, Gessnerium mochimaensis, Skeletonema costatum during summer. Also, all these species are considered as indicator of pollution with except Gessenerium sp. The average phytoplankton standing crop reached about 156 and 194 thousand units.l-1 during spring and summer, respectively. The outer part of the harbor [western sector] was more productive than the inner part [Eastern sector]. Statistical analysis dealing with the changes in community structure was concerned with univariate [diversity] and multivariate [graphical and prediction] treatments. The latter one was applied to phytoplankton community data in relation to the physicochemical parameters. Results indicated that the western harbor is mostly polluted as supported by a moderate average of diversity value of 1.44. The graphical multivariate correspondence analysis was more advantageous over both clustering and MDS plots in that it gives the natural grouping of the stations, beside evaluating the leading classes and environmental variables responsible for community change. Multiple regression analysis illustrated also excellent equations model for the phytoplankton in the western harbor during spring and summer which can be applied to predict the phytoplankton crop in the two seasons

Effect of application of inorganic fertilizers on the benthic fauna of the Nozha hydrodrome [Egypt]

Qualitative and quantitative estimations of bottom fauna was carried out monthly in the Nozha Hydrodrme [Egypt] during the period October, 1986 September, 1987. As a result of the reduced conditions which prevailed at the botton after prolonged additions of inorganic and nitrate fertilizers and increased eutrophication of water perior to the present investigation, the chironomus larvae and the oligochaete paranais sp. Dominated the community and contributed numerically 59.4% and 34.2% of the total benthos respectively, while gammarus spp. Formed only 6.3%. previous estimations of the benthic fauna before application of these fertilizers revealed the dominance of Corophium spp. Which constituted more than 86% by number of the total benthos while they disappeared totally in the present investigation. Also the biomass of bottom fauna has decreased from 6.3 gm fresh wt/m[2] in 1955 to 2.06 gm fresh wt/m[2]. results emphasize the importance of carrying out parallel quantitative estimations of benthos beside that of the phytoplankton and zooplankton communities during periods of application of fertilizers in order to maintain the optimum concentration levels of these fertilizers which yield the most favourable balance between these 3 components