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Background: Fish is considered an important food because it includes main nutrients (proteins, fats, and ash) and micronutrients (vitamins and minerals). The assessment of fish nutritional content data may offer crucial recommendations regarding freshwater fish consumption and preserving human well-being. Aim: Evaluate the safety and quality properties of Nasser Lake fish, Aswan, Egypt. Methods: A total of 250 samples, 50 of each Nile tilapia, Nile perch, Zander, Catfish, and Elephant-snout, from Nasser Lake, Aswan, Egypt; beheaded, eviscerated, filleted, and minced for determination of proximate analysis, amino acid, fatty acids, minerals and heavy metal, histamine content, cholesterol content, and sensory assessment. Results: The proximate analysis showed that all the samples examined were of good protein sources, with mean values ranging from 15.92% to 22.89%. Nile perch exhibits the highest levels of total fatty acids and amino acids. Heavy metal concentrations varied considerably among the analyzed samples, with a significant variance in the detection of metals among the examined fish. The findings show low histamine and cholesterol levels in the examined species, and were in accordance with those set by the National Food Safety Authority (NFSA) and the European Union Commission (EC). Accordingly, all samples are accepted based on their sensory properties. Conclusion: Nasser Lake fish are of high nutritional value and have an excellent supply of amino and fatty acids. [Open Vet J 2024; 14(6.000): 1403-1416]

The Electric Catfish, Malapterurus electricus, a species from order Siluriformes is widely distributed in Africa and occurs in all freshwater systems. It is a commercial species in Nasser Lake fisheries, with an average annual catch of about 130 MT. Limited biological data are available on this species. In the present study, random samples of M. electricus were monthly collected from the commercial catch of the lake's main landing sites during 2019. A total number of 538 specimens of M. electricus were collected for biological investigations. Results revealed that the total length ranged from 24.0 to 51.5cm, and the total weight ranged from 192.4 to 2785.9g. The length-weight relationship, with a statistically highly significant coefficient (R2= 0.9127) showed a tendency of the b-value (2.89) towards negative allometric growth. The estimated mean condition factor (Kc) was 1.483 ± 0.238 for combined sexes. Vertebrae were used for age determination, and six age groups were identified. Age groups III+ and IV+ were the most dominant in the catch since they constituted about 54.3% and 30.7%, respectively. The sex ratio revealed that the male percentage was higher than that of females (60% males to 40% females) in all samples. The spawning season of M. electricus extended from July to October during the study period. This study afforded biological data about electric catfish in Lake Nasser to sustain the catch and provide necessary information to benefit the exploitation of its resources. [ABSTRACT FROM AUTHOR]

Underwater sonar survey using Side Scan Sonar (SSS) and Single beam Echo-sounder (SBES) was used for the investigation of the old Nubian archaeological villages buried within the bottom topography of Nasser Lake. The research objective involved emphasizing the efficiency of marine geophysical techniques in the detection of the submerged old Nubian Villages in Nasser Lake behind the High Dam, the study also aimed to study riverbed topography and determining the old course of the Nile River in the area. The resulted bathymetric maps showed that the two former banks of the Nile River in the study area were characterized by two distinct natures, while the shoreline has retreated with different extents starting from 250 m at the southern regions up to 3 km in the northern parts. The high-resolution sonar images of the bottom uncovered distinctive acoustic patterns according to difference in the returned backscatter strength. Submerged Nubian houses were detected along some areas of the eastern bank, which were found either standing over elevated rocky cliffs or built on multiple tiered levels. Precise target measurements were applied on the detected houses and different dimensions were obtained, which suggest that these houses were built according to the availability of suitable land to construct such dwellings.

Underwater sonar survey using Side Scan Sonar (SSS) and Single beam Echo-sounder (SBES) was used for the investigation of the old Nubian archaeological villages buried within the bottom topography of Nasser Lake. The research objective involved emphasizing the efficiency of marine geophysical techniques in the detection of the submerged old Nubian Villages in Nasser Lake behind the High Dam, the study also aimed to study riverbed topography and determining the old course of the Nile River in the area. The resulted bathymetric maps showed that the two former banks of the Nile River in the study area were characterized by two distinct natures, while the shoreline has retreated with different extents starting from 250 m at the southern regions up to 3 km in the northern parts. The high-resolution sonar images of the bottom uncovered distinctive acoustic patterns according to difference in the returned backscatter strength. Submerged Nubian houses were detected along some areas of the eastern bank, which were found either standing over elevated rocky cliffs or built on multiple tiered levels. Precise target measurements were applied on the detected houses and different dimensions were obtained, which suggest that these houses were built according to the availability of suitable land to construct such dwellings. [ABSTRACT FROM AUTHOR]

In the framework of the French–Egyptian Imhotep Project, two spring gravimeters have been installed in the area of Lake Nasser (Egypt) with the aim to establish a first reliable gravity tide model for the region. The two tidal gravity stations are located in Aswan, on the northern edge of the lake and in Abu Simbel in the south, respectively. This study was mainly aimed to obtain a reliable model of the crustal response to tidal forces and, consequently, to increase the accuracy of the geodetic observations, to be used in future geophysical studies in this region as well as to investigate the effect of the Lake level variations on the crustal deformation and related gravity changes. Nearly 3 years of gravity records (from May 2018 to April 2021) were collected. Since no scale factor was available for the two gravimeters, the first step of this study was to achieve a reliable calibration for each of the two collected gravity signals. After removing the instrumental drift, spikes, steps and tares, both gravimeters have been calibrated by fitting the output signal against a synthetic reference signal based on the body tidal gravity response due to Wahr-Dehant Earth model and FES2014 ocean tidal loading model. The calibrated signals have been analyzed with ET34-X-V80 software for tidal analyses. This enabled us to retrieve a set of frequency-dependent gravity factors (amplitude and phase) for the main tidal waves, as well as to obtain gravity residuals. It turns out that the accuracy of the amplitude estimates for the main tidal waves is 0.2 ÷ 1% for LCR_ET16 in Aswan and 1 ÷ 10% for the LCR_D-218 in Abu Simbel. To improve the tidal model at Abu Simbel, LCR_ET16 was stopped in Aswan and relocated there. The first 90 days of gravity recordings from ET16 at Abu Simbel provide promising results, with an accuracy of the order of 0.1% for the main tidal waves, even better than the results obtained in Aswan. The residual gravity signal after tidal subtraction at Aswan is in the range of ± 50 µGal. Further analyses of the instrumental contribution are however needed before to be able to interpret this gravity signal in terms of surface loading (i.e. changes in the water level of Lake Nasser) or underground hydrology. [ABSTRACT FROM AUTHOR]

This study aims to compare the changes in the physicochemical and biological characteristics simultaneously in Nasser Lake as lentic water and the main Nile River as lotic water due to the construction of the Aswan High Dam. Therefore, water samples were seasonally collected from four sites along the lentic water and five sites along the lotic water. The results showed an increase in the water temperature and pH in the lentic than the lotic waters, while TSS, nutrients, BOD, and TDS showed a reverse trend. Furthermore, zooplankton recorded 45 taxa; 31 rotifers, 7 cladocerans, and 3 copepods, in addition to 4 taxa represented in rare groups. Rotifera dominated the main river water, while Copepoda dominated Nasser Lake water. Twenty-two holozooplankters appeared only in the main river water, while three holozooplankters appeared in the lake water and 20 holozooplankters were shared in both waterbodies. The appearance of Ptygura libera in the river for the first time proved that the lake is the source of some zooplankters in the river. According to the trophic state index and the river pollution index calculations, the two waterbodies categorized as eutrophic and unpolluted, respectively.

Lake Nasser is considered one of the largest artificial lakes in the world. Despite that, the amount of fish produced from it is not commensurate with its area. Therefore, this research aimed to (1) study the current production indicators and assessment of the productive and economic characteristics of Lake Nasser, (2) study the economic and environmental problems that Impeding development in Lake Nasser and proposals for its solution. The research reached several results, the most important of which is that the minimum production of Lake Nasser reached about 18.4 thousand tons in 2016, while the maximum reached about 37.7 thousand tons in 2009, with an annual average of about 25.2 thousand tons during the study period from 2005- 2018, which represents about 1.9% of the total fish production in Egypt during the same period, which amounts to about 1356.2 thousand tons. The minimum number of boats in Lake Nasser was about 0.68 thousand boats in 2011. When the maximum number of boats in Lake Nasser reached about 3.06 thousand boats in 2017, with an annual average of about 2.56 thousand licensed boats during the study period, and it was noted that no licenses were issued to fishermen during the years 2013 and 2016, while the maximum number of fishermen in Lake Nasser reached Nasser about 11.43 thousand fishermen in 2017, with an average An annual average of about 2,16 thousand fishermen during the study period, and the annual average production of tilapia, albedo fishes and other species was about 14.9, 4,3 and 6 thousand tons, respectively, during the study period. It was also found that they are the problems that inhibition development in Lake Nasser is the multiplicity of supervisory bodies, and the lack of trained workers to live in the conditions of the lake, and one of the most important recommendations was to unify the authority to supervise the lake, and to take care of fishermen in terms of social and health. [ABSTRACT FROM AUTHOR]

Background: Fish is considered an important food because it includes main nutrients (proteins, fats, and ash) and micronutrients (vitamins and minerals). The assessment of fish nutritional content data may offer crucial recommendations regarding freshwater fish consumption and preserving human well-being., Aim: Evaluate the safety and quality properties of Nasser Lake fish, Aswan, Egypt., Methods: A total of 250 samples, 50 of each Nile tilapia, Nile perch, Zander, Catfish, and Elephant-snout, from Nasser Lake, Aswan, Egypt; beheaded, eviscerated, filleted, and minced for determination of proximate analysis, amino acid, fatty acids (FAs), minerals and heavy metal, histamine content, cholesterol content, and sensory assessment., Results: The proximate analysis showed that all the samples examined were of good protein sources, with mean values ranging from 15.92% to 22.89%. Nile perch exhibits the highest levels of total FAs and amino acids. Heavy metal concentrations varied considerably among the analyzed samples, with a significant variance in the detection of metals among the examined fish. The findings show low histamine and cholesterol levels in the examined species, and were in accordance with those set by the National Food Safety Authority (NFSA) and the European Union Commission (EC). Accordingly, all samples are accepted based on their sensory properties., Conclusion: Nasser Lake fish are of high nutritional value and have an excellent supply of amino and FAs., Competing Interests: The authors claim no conflicts of interest in publishing this research.

Water resources have become world social and economic concerns. Lake Nasser provides more than 95% of the Egyptian freshwater funds. Wadi Al-Rayan lakes are man-made with a vital role in irrigation water and fisheries. The present study was aimed to investigate and compare the effect of heavy metals (Fe, Zn, Mn, Cu, Pb and Cd) accumulation in muscles, liver and gills on the health status of O. niloticus collected from both lakes, and the potential human health hazard of consuming those fish. The results demonstrated that, the accumulation of different metals arranged in the following order; Fe˃ Zn˃ Mn ˃Cd˃ Cu> Pb in Nasser Lake, while the order was Fe˃ Zn˃ Mn ˃Cu˃ Pb>Cd in Wadi Al-Rayan Lake. The metal pollution index (MPI) in fish tissues followed the order: liver > gills > muscles. Moreover, the biochemical indices of O. niloticus from both Nasser and Wadi Al-Rayan Lakes showed a significant alteration due to metal pollution. Moreover, the human health hazard index recorded an adverse health effect for habitual fish consumers from Wadi Al-Rayan Lake during both seasons, while the same hazard recorded in spring for habitual fish consumers from Nasser Lake which yield an alarming concern for fish consumers’ health. [ABSTRACT FROM AUTHOR]

This study aims to compare the changes in the physicochemical and biological characteristics simultaneously in Nasser Lake as lentic water and the main Nile River as lotic water due to the construction of the Aswan High Dam. Therefore, water samples were seasonally collected from four sites along the lentic water and five sites along the lotic water. The results showed an increase in the water temperature and pH in the lentic than the lotic waters, while TSS, nutrients, BOD, and TDS showed a reverse trend. Furthermore, zooplankton recorded 45 taxa; 31 rotifers, 7 cladocerans, and 3 copepods, in addition to 4 taxa represented in rare groups. Rotifera dominated the main river water, while Copepoda dominated Nasser Lake water. Twenty-two holozooplankters appeared only in the main river water, while three holozooplankters appeared in the lake water and 20 holozooplankters were shared in both waterbodies. The appearance of Ptygura libera in the river for the first time proved that the lake is the source of some zooplankters in the river. According to the trophic state index and the river pollution index calculations, the two waterbodies categorized as eutrophic and unpolluted, respectively. [ABSTRACT FROM AUTHOR]

Nasser Lake provides more than 95% of the Egyptian freshwater budget. The levels, spatial distributions, and risk assessments of heavy metals and natural radioactivity were investigated in the water and sediments in the main channel and khors (side extensions) of Nasser Lake in January 2017. Several indices were used to determine the quality and pollution degree of the water and sediments. The water indices included the heavy metal pollution index and metal contamination index, while the sediment indices were based on the (a) the metal levels as the enrichment factor and geo-accumulation index, and (b) the radioactivity as radium equivalent activity, absorbed dose rate, and external hazard indices. All index values were lower than their global mean values. Also, the results of the noncarcinogenic human health risk via water ingestion were below the threshold risk level. The obtained results indicate the safely used of Nasser Lake water for different purposes. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) pollution of water is a continuous worldwide issue in both developing and developed countries. HMs are resistant and non-degradable elements that are introduced to the water bodies via natural and anthropogenic processes. The main anthropogenic sources are agriculture, industrial and domestic wastes that are increased due to the increase of the global population. The existence of HMs at high levels, both essential and nonessential HMs can cause dangerous complications in the aquatic system, plants, animals and human health. Nasser Lake and the Nile River are the main sources of freshwater in Egypt. Anthropogenic heavy metals may pass to Nasser Lake via the discharged of pollutants into the Nile upstream of the lake. Despite that, the Nile River in Egypt receives different wastes from point and non-point pollution sources along its banks, the levels of most HMs decline and are within the national and global permissible levels in the areas far from the hot spots (pollution sources). The present article's interest is in the nature, sources and effects of the HMs in the aquatic environment in addition to the long-term changes of HMs content in the water and sediments of Nasser Lake and the Nile River in Egypt. [ABSTRACT FROM AUTHOR]

The Aswan High Dam located at the north of Nasser Lake in Aswan, Egypt, has a vital role because it is a multipurpose project for sustainable irrigation development, hydropower, and navigation improvement. In this work, we aim to detect the hazardous subsurface structures that control the South Aswan area and their causative source depths, through the application of both normalized standard deviation filters and deconvolution procedures. These computational approaches utilize a three-dimensional Euler homogeneity equation with unprescribed structural indices that is based on the properties of the differential similarity transformation on the available Bouguer gravity data. Hence, without any bias to a definite structural element (structural index), an automatic identification of the effective structural indices in the area is given. Moreover, possible vertical magnetic contacts are estimated from the reduced to pole magnetic anomaly map through an application of the tilt-depth technique. The mean focal depth of the earthquakes changes over time and migrates to shallower depths. The number of shallow events is increasing dramatically, whereas the corresponding magnitudes are decreasing. The integration of potential field data analysis with the new seismological and water level catalog (for the duration of 30 years) shows that the area began a hazardous cycle of activity (MI > 4) that could continue over the next few years. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the abundance, distribution, diversity and condition factor of Mormyrids in Oyan Dam lake, Abeokuta North Local Government Area of Ogun State, Nigeria. The fish were sampled from the catches of the fishermen in Oyan Dam lake, which used gillnets of 30-80 mm laterally stretched mesh size. The fish were sampled monthly between February and September 2011, at two different sites (Imala and Ibaro). The results revealed that a total number of 100 fishes of six species belonging to the family Mormyridae were collected. Numerically, catches were dominated by Mormyrus rume (34%), Hyperopisus bebe (30%) and Petrocephalus bane (24%). Together, these species comprised 88% of all collected individuals. Marcusenius ihuysi was rare and least in number representing 1% of the fish caught. The results showed that only four species were recorded in the dry season, namely Mormyrus rume, Hyperopisus bebe, Petrocephalus bane and Mormyrus deliciosus while five species were recorded in the wet season particularly in September. Mormyrus deliciosus, was not recorded in the wet season. In terms of body weight, the highest mean value was recorded for Mormyrus deliciosus (435.71 ± 95.71), followed by Mormyrus rume (143.82 ± 5.55) and Hyperopisus bebe (123.5 ± 5.26) while Petrocephalus bane was the least one (95.00 ± 8.56). The results also showed that the condition factor during the wet season (4.18) was higher than the condition factor of the dry season (3.51). Simpson's index was used to determine the species richness, while Shannon-Wiener's Index was used to evaluate species diversity; species evenness was equally evaluated using Pielou's Index. The indices of diversity included (d) = 0.31 and 0.23, H = 1.18 and 1.53 and E = 0.851 and 0.853 respectively for the two sites at Oyan Dam lake. The estimates from these indices indicated a low fish species composition and richness, also unevenness in the population of Mormyrids in Oyan Dam lake. Therefore, it will be advisable to regulate the activities of fishers in the water body to allow future increase in the abundance of this species. [ABSTRACT FROM AUTHOR]

Least-squares prediction using an empirically deduced local covariance function was performed to investigate the horizontal gradient of vertical movements (tilting movements) and possible position of block boundary around the Kalabsha fault, north west of the Nasser Lake, Egypt. Levelling data covering the Kalabsha area in the interval 1986 - 1992 were used. First approximated a covariance function of the rates of vertical crustal movement with a Gaussian form function is estimated and used it to segregate signal (rate of vertical movement rate) and noise in observed data. Then, the signal at grid points of 400 × 400 m2 mesh covering the Kalabsha area was estimated. After that, the estimated signal was differentiated in space to calculate the tilting movements. Finally, the position of possible fault zones or blocks boundaries in the Kalabsha area was delineated from the obtained continuous distribution of tilts of the deformed surface. By the present method, the subsidence in the southern part of the Kalabsha network relative to its northern was well reproduced. The pattern of tilt movements shows a low zone of tilt movements in the middle of the studied region surrounded by high tilt areas. The rate of tilt movements reaches about 0.35 microradian/yr in the southern high tilt area. Moreover, the delineated position of the fault zone or the block boundary in the area is in a good agreement with the wellknown trace of Kalabsha fault. [ABSTRACT FROM AUTHOR]

Summary: This paper examines the sensitivity and uncertainty of evaporation estimates from Nasser Lake, south of Egypt using data collected at the floating station Raft, 2km upstream of the Aswan High Dam, and 12 evaporation models. Based on their approach the evaporation models were ranked in five classes, respectively the Bowen ratio energy budget (BREB) approach, three energy–aerodynamic based methods, a mass transfer method, two temperature and five solar radiation–temperature approaches. State dependent parameter models were used to estimate the sensitivity indices of the different evaporation estimation methods at daily and monthly frequencies. A drastic reduction in the cost of the sensitivity analysis was obtained when coupled with efficient sampling methods, producing quasi-Monte Carlo sequences (Latin Hypercube samples). Analysis of the sensitivity indices (Si ) revealed that the energy and advective parameters (Qx and Qv ) in the Bowen ratio energy budget method most strongly affect evaporation estimates. The most sensitive parameters for the energy–aerodynamic methods (Penman, Priestley–Taylor and the deBruin–Keijman methods) are the change in heat storage (Qx ) and solar radiation. For the other methods the most sensitive parameters were solar radiation, air temperature and vapour pressure, but with lower sensitivities. After investigation of the first and second-order sensitivity indices, it was found that the first-order sensitivity indices capture more than 90% of the total variance of the evaporation estimates. Interactions between input parameters were found limited with a maximum contribution to variance of less than 3.3% for daily frequency and less than 8.5% for the monthly frequency. Results indicated that many parameters in the 12 evaporation models could be fixed without appreciably affecting the output of these models. This helped to reduce the computational load of these models. The uncertainty results show that the Dalton group is subject to the highest error. The overall uncertainty ranged from 9% (BREB method) to 15% (mass transfer method) of the mean evaporation rate. [Copyright &y& Elsevier]

To know the interrelationship between some metals in different ecosystem components (water, sediment, aquatic plant and fish), many samples from these components were collected from four bights at the Nasser Lake, Egypt, and analyzed for Fe, Mn, Zn, Ca, Mg, Pb, Cd, Ni, Co, Cu and Cr using atomic absorption spectrophotometer. Different distribution factors (bioaccumulation factor - BF, discrimination factor - DF and enrichment factor - EF) were applied on the results of analysis. Data showed that the relatively high concentration of measured metals in water samples are derived from fish farms, and discharge of tourism and trade ships. Applying single leaching sequential technique on sediment samples, using different extracting solutions, revealed a strong ability of trace metals to adsorb on or co-precipitate with amorphous Fe/Mn oxides. High concentrations of Fe, Mn, Co and Ni were measured in the intestine while high Cd and Cr concentrations were recorded in the stomach in both Tilapia (nilotica and galilea). Tilapia galilea accumulated high Pb, Cu and Zn concentrations in their stomach, while in nilotica high concentrations of Pb, Cu and Zn were measured in the intestine, liver and muscles, respectively. Myriophyllum spicatum (an aquatic plant) in the lake recorded high concentrations of Fe, Mn and Zn. Bioaccumulation factors of studied elements in the different bights components indicate that the elevated concentration of measured elements in the aquatic plant and Tilapia (nilotica and galilea) are derived from water, reflecting the increase of human activities in Nasser Lake in recent years. However, the present study concluded that all the elements studied were still below the natural back-ground levels, except Zn and Cu. [ABSTRACT FROM AUTHOR]

High and Aswan Dams Authority (HADA) proposed a plan aiming at constructing a rockfill dam in the Kalabsha area, about 60 km south of Aswan High Dam. The aim of this dam is to restrain the overflow of water to the Kalabsha Valley for keeping one billion cubic meters from being lost due to seepage and evaporation. The safety of dams during earthquakes is extremely important because failure of such a structure may have disastrous consequences on life and property. Therefore, different factors were considered as part of a site assessment. Five seismic source zones, close enough to the site to give rise to potentially damaging earthquake ground motions, were identified. Seven active faults that have the potential for producing significant earthquakes and that pass through or near the dam site were also identified. The earthquake loading represented by ground motions at the site was evaluated. Probabilistic seismic hazard procedures were used for assessing the earthquake loading at six individual sites using Area-and Line-Source Models (ASM & LSM). The ASM is based on current observed seismicity, whereas the LSM is based on geological slip rates. The output represents the expected acceleration amplitude with 90 percent probability of not being exceeded in exposure times of 20, 50, and 100 years. The results from the two models appear to be different, the expected ground motions from ASM were twice as high as expected from LSM. This difference is due to the load of the Aswan reservoir (Nasser Lake) triggering earthquakes on those parts of the faults that lie under the lake at Kalabsha area. The hazard at the selected sites is given by “the hazard curve” that is represented by the relationship between the peak ground acceleration and its annual exceedance probability. By comparing the curves for the six individual sites for the same source model, it can be concluded that the potential ground acceleration level for all the sites is almost the same. Considering the mean results from the two models, the annual exceedance probability of the expected ground acceleration from ASM is approximately ten times higher than the annual exceedance probability from LSM. Since ASM is based on current seismicity, it is more appropriate forrepresenting the actual hazard for the dam site. [ABSTRACT FROM AUTHOR]

Abstract: In Egypt, the Nile River water is the main source of water, providing nearly 95% of water requirements. The Nile water is impounded in Lake Nasser (LN) in the south of Egypt by the High Aswan Dam (HAD). In this study, we presented the radioactivity levels in LN sediments over the time period 1992–2000 and the distribution pattern of the measured radionuclides (238U series, 232Th series, 40K and 137Cs). In addition, the uranium concentration in water samples was measured. The distribution pattern of these radionuclides in sediments reflects the geochemical behavior and weathering processes of uranium series, thorium series and the heavy minerals in the Nile pathway and in Nasser Lake. [Copyright &y& Elsevier]