Spatial and temporal variations of macrobenthic fauna in Lake Nasser khors, were studied at four subsequent seasons during 2013. Khor Tushka West recorded the highest average number (597 Org./m 2 ). It was decreased at khor Kursku (112 Org./m 2 ) and Kalabsha (105 Org./m 2 ) while it reached the lowest at khor Wadi Abyad (65 Org./m 2 ). The highest average number was recorded during spring (447 Org./m 2 ). It decreased during winter (174 Org./m 2 ) and summer (151 Org./m 2 ), then reached the lowest during autumn (107 Org./m 2 ). Annelida, Arthropoda and Mollusca were the most dominant groups in the lake during the study being 72.65%, 26.09% and 1.35%, respectively. The highest number of species (16) was observed at khor Kalabsha. This may be due to its nature of sandy bottom. Biological indices showed high richness values of all the studies khors except khor Tushka West.These low values of indices may be due to the dominance of Annelids species especially, Limnodrilus spp. and Branchiura sowerbyi. There is a positive correlation between these species and total annelids with all physico-chemical parameters. The analysis of variance between the different khors based on the main macrobenthic groups showed a highly significant value ( p < 0.001). ª 2014 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/).
This study was conducted to evaluate the impact of human activities on the ecological health and food chain at the shores of four Nile Islands in Great Cairo including El-Qeratten, El-Waraq, El-Zamalek, and El-Manial. Water quality, bacteria, phytoplankton, benthic algae, zooplankton, macrobenthic invertebrates, and bony fishes were examined at each island shore over two seasons including the lowest and the highest flow (February and July 2020, respectively). The obtained results showed that the average values of most of the chemicals in Nile Island’s water were within the Egyptian water quality limits. Discriminant analysis of physicochemical factors revealed a similarity between El-Waraq and El-Qerateen and between El-Manial and El-Zamalek. El-Qeratten was the most polluted island. It has the highest total and fecal coliform bacteria count (3.155 and 3.050 Log MPN/100 mL, respectively). El-Zamalek shores have the highest phytoplankton (33,582 cells × 104 L−1) and zooplankton count (310,891 organisms × m−3) and phyto-biochemical values. Biochemical analysis of phytoplankton demonstrated the richness of the bulk by protein (> 85% of biomass), indicating that phytoplankton has a high nutritional value. Elevated zooplankton count was recorded at El-Zamalek, which coincided with the peak of phytoplankton abundance. Mollusca were the dominant macrobenthic invertebrates on most of the island’s shores. Bony fishes were represented by 27 species and two crustaceans. The levels of the metals in fish samples were compared with the food safety guideline endorsed by the World Health Organization and Food and Agriculture Organization (WHO/FAO) to evaluate the toxicity level.
Sediments are utilized as a marker for events that endure long enough to manifest their environmental impacts and determine the contamination levels. The purpose of the present study was to highlight the current sediment quality of four Nile islands shores by utilizing a variety of physical, chemical, and biological aspects and indices. In addition, the status of benthic diatoms and macroinvertebrates, as well as their responses to sediment variables were investigated. The metals followed a decreasing concentration order: Al > Fe > Mn > Zn > Ni ≈ Cr > Cu > Co > Pb > Cd. The outcomes of metal pollution indices revealed some localized contaminated sites, by mostly Ni and Cd. In addition, a moderate toxic risk from metals was observed for El-Keratten shores, while the sediments of El-Warraq, El-Zamalek, and El-Manial islands shores were at low toxic risk. A total of 112 diatom species belonging to 24 genera were identified in the total sample set, where most of the diatoms encountered were cosmopolitan. Metals had a remarkable impact on the composition, distribution, and dominance of diatom assemblages, but had little effect on diatom diversity, while there was a noticeable effect of grain size on diatom distribution and diversity. Thirty-four species of benthic invertebrates were identified in the collected samples from the islands shores. The dominant taxa and groups of benthic invertebrates at different islands were affected by various sediment parameters, where the levels and types of such variables differed from one species to another.
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