This article describes the development of a Nile Biotic Pollution Index (NBPI) for the River Nile in Egypt. Chemical data were collected from 30 locations along the Nile from Aswan to Cairo and 21 sites within the river delta, incorporating a range of conditions from unpolluted to grossly polluted. Seven chemical variables were used to calculate a Nile Chemical Pollution Index (NCPI) for each site. Biological data were collected primarily using Artificial Substrate Samplers (ASS). The UK developed, Biological Monitoring Working Party (BMWP) biotic index and the BMWP-ASPT were applied to the data. A Nile Biotic Pollution Index (NBPI) and the NBPI-ASPT were obtained by incorporating more of the Nile taxa. There were highly significant regressions (P \ 0.001) for both the UK and the Nile Pollution Index scores with the NCPI for the whole river. The modification of the UK indices improved the Nile Indices increasing the number of taxa recorded from 29 to 43 and the total number of recorded taxon occurrences from 377 to 490. The Nile Indices provided better discrimination at both ends of the pollution spectrum. The NBPI-ASPT was best for the river as a whole, and particularly for the river from Aswan to Cairo. The NBPI was much better in the delta than from Aswan to Cairo. These differences in performance were attributed to the fact that the NBPI-ASPT excludes information on taxon diversity. In clean waters there was a wide range of NBPI score suggesting that the biodiversity of taxa is dependent on other aspects of habitat quality. Conversely in the polluted delta the high score of an individual taxon is critical for the NBPI-ASPT as it may have a distorting effect. As the NBPI-ASPT was the most consistent biotic index it is recommended as the regular biological assessment and regulatory tool for Egypt to meet the requirements of the Convention for Biodiversity.

The composition and distribution of zooplankton communities in three depths (surface, 10-5 m and 20-15 m depths) along main channel of Lake Nasser were studied in 2013. The density of total zooplankton was increased to maximum during winter and autumn at surface water (39,362 and 63,100 Ind. m À3 , respectively) and gradually decreased with depth until attaining the lowest average density at 20-15 m (12,460 and 8976 Ind. m À3 ). During spring and summer, zooplankton was irregularly distributed through the water profile, where the highest average density was recorded at 10-5 m depth (66,007 and 66,734 Ind. m À3 ). Copepoda was the dominant zooplankton group at all depths, it represented about 70-76.2% of the total zooplankton count. Cladocera formed about 13.4%, 14.5% and 11% of total zooplankton density for surface, 10-5 m and 20-15 m depth. It was decreased with increasing depth during winter and autumn; however it attained its maximum density at 10-5 m depth during spring and summer. Rotifera average density decreased with increasing depth. The dominant zooplankton species inhabiting Lake Nasser were strongly temperature-dependent. The study recommends the introduction of some pelagic fish species to consume the high persistence of zooplankton community at the upper 10 meters of water column. ª 2015 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. 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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