The marine environment of the East Mediterranean has been considerably impacted in modern times by two man-made changes: the creation of a waterway between the Indo-Pacific and the Mediterranean basins and the control of the Nile fresh-water outflow. The opening of the Suez Canal caused a migration generally from the Red Sea to the Mediterranean, and rarely in the opposite direction as the Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrientpoor eastern Mediterranean. Accordingly Red Sea species invaded the Mediterranean ecosystem and not vice versa; this phenomenon is known as the Lessepsian migration or erythrean invasion. The composition of zooplankton in the eastern Mediterranean has been shown to include a large proportion of Indo-Pacific and other circumtropical species which have successfully settled and proliferated in this environment. During the present study, an overview is provided on zooplankton migration through Suez Canal and its impact on the ecological system based on published literature. It is also meant with the hydrographic and zooplankton characteristics of the adjacent seas. It is clear that, except jellyfish Rhopilema nomadica, the negative impact of zooplankton Lessepsian migratory species in the Egyptian Mediterranean waters is not evident. Finally, it would be concluded that, a continuous monitoring programme will be needed to record the recent erythrean zooplankton species and follow up the distribution and abundance of those previously recorded as aliens to assess their impacts on the native biodiversity of the Mediterranean. ª 2015 Hosting by Elsevier B.V. on behalf of National Institute of Oceanography and Fisheries. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Lake Edku receives huge amounts of waste waters discharged from various effluents that could be affecting on its ecological and biological features. Samples were collected seasonally for seven subsequent years (2009-2015) from 9 stations represent the different habitats in Lake Edku to assess the ecological status of the lake through long-term variations of zooplankton community. The data of physico-chemical parameters indicated that some parameters had wide variations in yearly average and others changed within narrow range. Lake Edku is considered among the highly eutrophic lakes as the average values of Chlorophyll-a concentrations all over the study period always higher than the eutrophication level. Zooplankton community in the lake comprised 77 species. Rotifera and Copepoda were the most abundant and diversified groups. Long-term variations of zooplankton abundance and diversity indicated that the lake is in continuous degradation. This also confirmed by the dominance of rotifer species belonging to genera Brachionus, Polyarthra, Keratella and Filinia which were considered as bioindicators of organic pollution. However, it would be concluded that Lake Edku is highly eutrophic basin, under severe conditions and their ecological status is too bad and needs repair.