Trophic state and potential productivity assessment for Qaroun Lake using spatial techniques.

Qaroun Lake is one of the most important Egyptian lakes which, recently, have been exposed to severe degradation in water quality and fish productivity. In this manuscript, Carlson's trophic state index (CTSI) was used to evaluate the trophic state, while the trophometric index (TMI) was used to assess the potential productivity of Qaroun Lake. The present study is one of the initial attempts to investigate these indices in Qaroun Lake. To achieve this work, an integrated multidisciplinary approach was adopted integrating field investigation, geographic information system, and data analysis. CTSI combines three variables of water quality: chlorophyll-a (CHL-a), total phosphorus (TP), and transparency measured by Secchi disk depth (SDD). The result of overall CTSI showed the hypereutrophic state is represented by 62% and eutrophic state is represented by 38% of the total lake's area. Moreover, the calculated TMI indicated the average potential productivity value (PP) is 619 t. It can be concluded that the hypereutrophic is the dominant state in Qaroun Lake. The present study recommends the application of TMI model to evaluate and monitor the changes in Qaroun Lake's potential productivity in response to the changing environmental conditions and other biological pressures (e.g., Isopoda paraside).

Evaluation of the ecological health and food chain on the shores of four River Nile Islands, Egypt.

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.

Applicability of Using Biological Indices to Assess Water Quality of the Nile Branches, Egypt.

<b>Background and Objective:</b> The Saprobity index (S) and the Wetland Zooplankton Index (WZI) are the most commonly used indices using zooplankton data to assess the water quality of many water bodies. However, these indices may be inadequate to assess the water quality of all freshwater bodies around the world. This study aims to evaluate the validity of these indices for assessing the water quality of the Nile branches (Damietta and Rosetta branches) as a case study. <b>Materials and Methods:</b> The validity of S and WZI is statistically tested against the Nile Chemical Pollution Index (NCPI) using linear regression analysis. The Physico-chemical parameters, zooplankton and Discriminant Analysis (DA) data show significant differences between the Damietta and Rosetta sites. <b>Results:</b> The results of both S and WZI do not coincide with those calculated with NCPI. The obtained S values show that all sites have poor water quality. On the other hand, the WZI values indicate that the Damietta branch sites in addition to the first two sites of the Rosetta branch (R₁ and R₂) have moderate water quality, while the other sites have poor water quality. <b>Conclusion:</b> Finally, the NCPI results show that the Rosetta branch sites are heavily polluted, while the Damietta sites are clean. This study concludes that S and WZI inaccurately describe the ecological status of the study area.