Search

Lake Nasser is a reservoir of freshwater for drinking and irrigation in Egypt and it constitutes an important share in the fisheries sector. This study aims to acquire a better understanding of the status of phytoplankton distribution in Lake Nasser under the current flood regime and before the construction of the Grand Ethiopian Renaissance Dam (GERD). Samples were collected from fifteen sites representing different lake sectors along the main channel of the lake during 2016−2017. Approximately 103 species were recorded, belonging to six different classes, dominated by Cyanobacteria, Bacillariophyceae, Chlorophyceae, whereas Euglenophyceae, Dinophyceae and Chrysophyceae were rare. Based on the abundance of phytoplankton species, the pre-flood and post-flood seasons were very well discriminated. A major blooming of Cyanobacteria in the Tushka sector was detected during the pre-flood season, whereas this phenomenon diminished in the post-flood period when Bacillariophyceae and Chlorophyceae appeared. The results of this study indicated that the most important factors affecting phytoplankton species distribution during pre-flood and post-flood seasons are temperature, nutrients and total dissolved solids. The study confirms that flood regime substantially affects the phytoplankton abundance and distribution in Lake Nasser.

Mortality of fish has long been recognized as the evident indication of pollution, nevertheless, the increasing low-level pollution may lead to a long-term decline and eventual extinction of fish stocks. This study investigates the impact of a point source pollution (El-Sail Drain) on the biological parameters of redbelly tilapia (Coptodon zillii) in the River Nile at Aswan, Egypt. The present results showed a significant variation of the physicochemical parameters and heavy metals of the River Nile waters in the vicinity of El-Sail Drain. On the other hand, metal concentrations in the gonads of C. zillii from the downstream of the pollution source were significantly higher than that of the unimpacted upstream area. The sex ratios of C. zillii varied in the two studied areas, where it was 1:1.38 in the unimpacted area and was 1:0.9 in the impacted area. While the GSI values of the impacted area were decreased significantly (p

The current study represents the first molecular characterization of freshwater fish species in Egypt from two major fish resources; the River Nile and Lake Nasser. A total of 160 DNA barcodes using a 655-bp-long fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene were generated from 37 species belonging to 32 genera that represent 15 families from nine orders. The studied species were identified using different molecular-based identification approaches, in addition to the morphological identification, including neighbor-joining (NJ) trees, Barcode Index Number, and Automatic Barcode Gap Discovery (ABGD). The average genetic divergence based on the Kimura two-parameter model (K2P) within orders, families, genera, and species were 0.175, 0.067, 0.02, and 0.008, respectively. The minimum and maximum K2P distance-based genetic divergences were 0.0 and 0.154, respectively. Nucleotide diversity (π) varied among families and ranged between 0.0% for families Malapteruridae, Auchenoglanididae, Schilbeidae, Anguillidae, Centropomidae and Tetraodontidae and 17% for family Cyprinidae. The current study cautions against the lack of species coverage at public databases which limits the accurate identification of newly surveyed species and recommends that multiple methods are encouraged for accurate species identification. The findings of the current study also support that COI barcode enabled effective fish species identification in River Nile and Lake Nasser. Moreover, the results of the current study will establish a comprehensive DNA barcode library for freshwater fishes along the River Nile in Egypt. Egyptian freshwater fish DNA barcodes will contribute substantially to future efforts in monitoring, conservation, and management of fisheries in Egypt.

Procambarus clarkii, as an invasive species, has proved to have an adverse impact on the Egyptian freshwater system, nevertheless, its fisheries could be one of many ecosystem services it can provide to society. This study aims to document the main fisheries characteristics of this species during 2014. Many fishing methods were found to capture P. clarkii including trammel nets (Estaquaza and extended nets), gill nets, and traps. About 70% of the individuals had carapace lengths between 39 and 52 mm and 95 % the individuals had a mean carapace length that exceeds the harvestable limit (35 mm). The length-weight relationship data of P. clarkii showed an allometric growth for weight more than for length (b > 3). The variations in male and female sex ratio with length classes showed that males of P. clarkii predominated all length classes except length classes 8 and 12 cm total length. The results of this study indicate that the crayfish grows considerably longer in the River Nile than it usually does in its original environment and that there is an assisted population, and high yields are expected when crayfish from the River Nile are to be utilized for commercial purposes.

Lake Nasser, a large man-made tropical reservoir, is located in the southern part of Egypt. The lakes’ fisheries have undergone a steady decrease during the last 10 years obscuring its potential for sustainability. Fisheries assessment study based on the fishing activities is essential to attain reliable information for construction a management plan to achieve rational and sustainable exploitation. Spatial and landing site surveys were conducted during the period from 2016 to 2017. More than 300 random fishing boats were examined to investigate their fishing gears characteristics, species composition, mean trophic level and catch per unit effort. More than 13,000 fish specimens from the catch were sampled and investigated for the gear selectivity study. The results indicate that trammel nets, gill nets and long-lines are the main fishing methods used. Thirty-four fish species were recorded in the lake, 6 of them were dominant, namely; Oreochromis niloticus, Sarothrodon galilaeus, Coptodon zillii, Lates niloticus, Alestes baramoze and Hydrocynus vittitus. The lake exhibits spatial variations in its productivity as the southern part is more productive. The time series of size and CPUE showed a high exploitation rate for the most important commercial fish species in the lake by the fishing gears used. Measures for fishery management based on gear selectivity are suggested for sustainability. Keywords: Lake Nasser, Fisheries management, Gear selectivity

This study focuses on changes in zooplankton composition and abundance in Lake Nasser during different flood periods before the construction of the Grand Ethiopian Renaissance Dam (GERD). Field surveys were carried out in August 2016 (flood period), December 2016 (post-flood period), and May 2017 (pre-flood period). Fifteen sampling sites representing five sectors were selected to cover the lake whole area. The results revealed a highly significant difference (p ≤ 0.016) in the density of all identified zooplankton groups among different flood seasons and lake locations. The zooplankton standing crop during the flood was higher, by a factor of approximately 3.7, than that recorded in post-flood and pre-flood periods. Zooplankton was dominated by medium-sized Copepoda, two cyclopoids (Thermocyclops neglectus and Mesocyclops ogunnus) and one calanoid (Thermodiaptomus galebi). The euplanktonic rotifer Keratella cochlearis dominated, during post-flood and pre-flood periods, constituting approximately 83% and 77% of total rotifer densities, respectively. Keratella tropica occurred in greatest density during flood made up 52.6% of total rotifers. Diaphanosoma mongolianum was the main cladoceran during flood and post-flood periods, whereas Ceriodaphnia dubia densities were highest for pre-flood periods. This study found that flood regime affect zooplankton composition and density in Lake Nasser.

This study focused on the monitoring and assessment of aquatic ecosystem functioning based on the abiotic and biotic features of Lake Nasser in the post-flood and pre-flood periods as the last ones before water storing behind the Grand Ethiopian Renaissance Dam. The physicochemical parameters, distribution and structure of biotic communities, including bacteria, phytoplankton, zooplankton, macrophytes, epiphytes and fish were analyzed at 15 sites. The values of most parameters (primarily temperature, total suspended solids, pH, orthophosphates, carbonates, sulphates and some cations) were higher in the pre-flood period, whereas higher values of conductivity, total dissolved solids, total solids, nitrites, nitrates, chemical oxygen demand, bicarbonates and chlorophyll a were recorded in the post-flood period. Cyanobacteria-dominated phytoplankton and total coliform bacteria were more abundant in the pre-flood period, and especially at sites 10–15, whereas higher abundances of zooplankton were recorded in the post-flood period. All these changes in parameters were significantly differentiated, and only the concentrations of dissolved oxygen, biochemical oxygen demand, ammonium and silicates were at similar level in both periods. The study also indicated that environmental factors had affected the macrophyte distribution and the adaptation of the invasive species Myriophyllum spicatum to thrive under different environmental factors in the lake. Besides, macrophytes provided the habitat to other aquatic organisms, especially epiphytes, and also helped maintaining the good water quality, nutrient cycling and stabilizing rivers’ and lakes’ banks. Generally, these conditions were rather favorable for biological processes and fish production.

This study outlines the immediate impact on local fisheries of the incident that took place on 21st April 2015. A barge capsized in the Nile in Upper Egypt’s Qena governorate after colliding with the foundations of the city's Dandara Bridge. The capsized barge was carrying 500 tons of phosphate (pre-industrial, inert material) for processing in a local factory. The study aimed to record any apparent effect of the incident on the fisheries in the immediate site vicinity and downstream. Also, it described the status quo of the fisheries around the incident location to compare it with the situation before the accident to confirm any short-term impact and to establish a baseline for any future, long-term, impact studies. Data were collected on fish assemblage structure in the incident site vicinity, the number of fishing boats and fishing methods that were applied to catch them. Furthermore, some fisheries biological parameters were assessed. The main conclusions derived from the study were that fishing in the vicinity of the incident is artisanal with small boats and simple fishing gears. The fisheries biological parameters of the area’s fishery are comparable to that of other similar environs, and that the incident did not have an apparent short term effect on the fishery profile of the area. The main recommendations resulted from this study were that the impact of the incident on fish at the molecular level should be studied and that the state of fisheries in the area should be followed up to detect any long-term impact of the incident.

This study was carried out to assess the effect of site on the spatial variations of sedimentological characteristics and heavy metal pollution of two semi-enclosed embayments of Lake Nasser. Grain Size, texture and mode of transportation as well as some heavy metals and organic matter were assessed in sediment samples from those embayments. The results indicated that the grain size of the lake sediments was affected by site variation. Moreover, heavy metal distribution in the sediments was mainly directed by grain size distribution and organic matter, though, the organic matter was more critical than grain size in controlling heavy metals distribution in each embayment. The main source of heavy metals in studied embayments was concluded to be the metals brought with flood waters rather than being of anthropogenic origin. The results also indicated the association of studied metals with Fe and Mn oxides of suspended matters and dissolved solids which come with flood water and trapped and settled to the bottom sediment in the stagnation period. Measured indices indicated that southern embayment is more polluted than northern one, which could be explained on the basis that the southern embayment reserves larger amounts of suspended matter coming with the flood than northern embayment.

Recently, tilapia have become increasingly important in aquaculture and fisheries worldwide. They are one of the major protein sources in many African countries and are helping to combat malnutrition. Therefore, maintenance and conservation genetics of wild populations of tilapia are of great significance. In this study, we report the population genetic structure and genetic diversity of the redbelly tilapia (Coptodon zillii) in three different Egyptian aquatic environments: brackish (Lake Idku), marine (Al-Max Bay), and freshwater (Lake Nasser). The habitat differences, environmental factors, and harvesting pressures are the main characteristics of the sampling sites. Three mitochondrial DNA markers (COI: cytochrome oxidase subunit I; the D-loop; CYTB: cytochrome b) were used to assess population structure differences among the three populations. The population at Lake Nasser presented the highest genetic diversity (Hd = 0.8116, H = 6), and the marine population of Al-Max Bay the lowest (Hd = 0.2391, H = 4) of the combined sequences. In addition, the phylogenetic haplotype network showed private haplotypes in each environmental habitat. Results presented here will be useful in aquaculture to introduce the appropriate broodstock for future aquaculture strategies of C. zillii. In addition, evidence of population structure may contribute to the management of tilapia fisheries in Egyptian waters.

Objectives: The aim of this article is to detect whether oral lesions affect the tongue mainly due to higher cells expressing angiotensin-converting enzyme 2 (ACE2) than in other oral sites in COVID-19 patients. Moreover, the etiology of oral lesions was evaluated either resulting from SARS-CoV-2 sequelae or from adverse effects of drugs used for COVID-19 treatment. Materials and Methods: One hundred and twenty-four patients were admitted to the study. All patients’ data were obtained including age and gender, laboratory testing, drug administration, respiratory and systemic conditions, signs and symptoms, and oral manifestations. Results: Oral manifestations were seen in 112 (90.3%) of all patients. Oral ulcers represented the most prevalent lesions in the oral cavity in 104 patients (92.8%). Lip, tongue, and labial mucosa showed the most common sites for oral ulcers. Most of oral lesions were displayed in the tongue in 96 patients (85.7%). Various medications were used in the treatment of patients. Conclusion: The tongue represented the most common site of oral lesions in COVID-19 patients followed by the labial mucosa. No correlation was found between the oral lesions and the drugs used for the treatment of SARS-CoV-2 infection. The systemic health and the severity of the disease were not related to the spread of the oral lesions.

Poole Harbour is typical of many heavily anthropologically impacted semi-enclosed estuarine coastal areas under pressure from metal pollution across the world. This study examined the physiological significance of metal burdens within that sensitive area, and assessed the potential use of metallothionein (MT) concentrations in two organisms: the common cockle (Cerastoderma edule) and the Mermaid's glove sponge (Haliclona oculata) for mapping the spatial extent of the biological response to metal contamination. A spectrophotometric method was applied for detection of MT in the bivalve, and for the first time to detect MT in sponges. The results show that while some metal concentrations in cockle and sponge tissues and in their surrounding environment (water and sediment) could be related to sources of metal contamination, MT values in the soft tissue of cockles and whole tissue of sponges are not. No relation could be found between MT in both cockles and sponges, and any of the tested metals (As, Cd, Cr, Cu, Pb, Hg, Ni, Ag, Sn, Zn). Furthermore, some of the lowest MT concentrations were detected in heavily polluted areas, indicating that MT concentrations in tested organisms are not exclusively associated with metal concentrations, as other environmental factors could affect induction of this protein. Organisms probably have a high tolerance to metal contamination and chronic exposure to a high level of contamination resulted in developing a variety of detoxification mechanisms. Results indicate that further study of metal stress in this type of ecosystem may need to examine other indicator species and/or apply a different biomonitoring technique.

Background: The aim of this study is to evaluate radiographic success of immediately restored dental implants placed immediately after extraction of periodontally compromised anterior teeth. Methods: In this prospective clinical trial human study, ten patients were selected from outpatient clinic of the Department of Oral Medicine, Periodontology, Oral Diagnosis, and Radiology, Faculty of Dentistry, Tanta University. Teeth were extracted as a result of sever periodontal destruction, followed by immediate implant placement and immediate implant restoration. Implant survival, bone level was evaluated for each patient at 6, 9 and 12-month follow-up period. Subtraction radiography was performed to compare the baseline image from 12 months follow up period image. Results: The survival rates of the immediately placed implants in the present study were 100%. Results showed significant reduction of the bone defect depth at 6, 9 and 12 months when compared to immediate post-operative record. Also massive increase of the mean bone density scores at 12 months when compared to immediate post operative record. Conclusion: Based on the results of this clinical trial, placement of implants immediately in fresh extraction sockets affected by periodontal disease followed by immediate restoration may be a valid operative technique that leads to predictable results if adequate preoperative and postoperative care is taken.

This study identifies and quantifies the spatial variations of metal contamination in water, sediment and biota: the common cockle (Cerastoderma edule) and the Mermaid’s glove sponge (Haliclona oculata), within a heavily anthropogenically impacted semi-enclosed estuarine–coastal area with a low ability to disperse and flush contaminants (Poole Harbour, UK). The results showed that metal contamination was detected in all environmental compartments. Water was polluted with As, and Hg sediment metals were mostly within “the possible effect range” in which adverse effects occasionally occurs. Cockles had considerable concentrations of Ni, Ag and Hg in areas close to pollution sources, and sponges accumulate Cu and Zn with very high magnitude. A systematic monitoring approach that includes biological monitoring techniques, which covers all embayments, is needed, and an integrated management of the semi-enclosed coastal zones should be based on the overall hydrological characteristics of these sensitive areas and their ability to self‐restore which is different than open coastal zones.