Egyptian Journal of Aquatic Research最新文献

The present work deals for the first time with the species diversity of gillnets operated on the fisheries coasts of Alexandria City from El-Montazah to Sidi Kirayr. A total of 6161 specimens of about 427 kg were collected during periods from Feb 2018 to Jun 2018 and from Dec 2019 to Nov 2020 using two types of gillnets: the demersal and the pelagic gillnets. All samples were identified and photographed. A total of 108 species were identified in the catch of gillnets (99 fish species; 1 molluscan species and 8 crustacean species). From that, 28 lessepsian species were recognized. The catch was dominated by Family Sparidae (25 species) and Family Scombridae (8 species). The results showed that the species and size composition of gillnets catch were depending on the type of the gillnet and its mesh size. The catch of the demersal gillnets represented 63.27% of the total production by number and 84.72% by weight of the total catch of gillnets, while the catch of pelagic gillnets represented 36.73% and 15.28% by number and weight of the total catch, respectively. Eighty nine fish species were caught by the demersal gillnets and 36 fish species were caught by pelagic gillnets. Diplodus vulgaris was the main species caught by the demersal gillnets and Boops boops and Sardinella aurita were the main species caught by the pelagic gillnets. On the other hand, according to mesh number, which is defined as numbers of meshes in half-meter length of net, the gillnets with mesh number 17–18 followed by gillnets with mesh number 20 were the main meshes for the demersal gillnets. As for the pelagic gillnets, they were restricted to mesh number 33–34. In addition, only mesh numbers 11, 14, 17–18, 20 and 25–26 (demersal gillnets) and mesh numbers 33–34 (pelagic gillnets) were operated all over the year. Only 7 fish species from the target production were represented in all seasons namely: D. vulgaris, B. boops, Diplodus levantinus, Diplodus sargus, Umbrina cirrosa, Lithognathus mormyrus, and Trachurus mediterraneus. The seasonal diversity index of fish species was H' = 1. 3652 and the large numbers of fish species recorded were in spring (61 species) followed by autumn (58 species), summer (47 species), and winter (27 species). Further biological studies are needed to identify the most dominant species caught by the gillnets operated in Alexandria.

One of the most important aquatic macro-invertebrates is Procambarus clarkii. This study was designed to evaluate the effect of depuration for 21 days on the total hemocytes count and heavy metals (Co, Cr, Pb and Hg) concentrations in the hemolymph and different tissues of P. clarkii. Two hundred crayfish were collected and were divided into two groups; field crayfish (FCF) that were dissected directly and the depurated crayfish (DCF) that were housed for 21 days in glass tanks. Procambarus clarkii were dissected to determine the total hemocytes count and heavy metal concentrations in the hemolymph, abdominal muscles, and hepato-pancreas. The results showed that the depuration has led to a significant decrease in the total count of hemocytes, however, it increased the percentages of semi-granular cells, granulocytes and decreased the percentage of hyalinocytes. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed different protein patterns between FCF and DCF. Not all the selected heavy metals were detected in the collected water samples and in the investigated tissues. Depuration has led to a significant decrease of the heavy metals, if present, in the hemolymph, abdominal muscles, and hepato-pancreas. Collectively, the depuration resulted in significant decreases in the total hemocytes count and eliminated the selected heavy metals from the different tissues of P. clarkii.

Culture-independent molecular study presented the first exploring and evaluation of prokaryotic communities in two desert brines; the athalassohaline Lake “Aghormy”, Siwa Oasis, Western Desert of Egypt, and the thalassohaline saltern “Sebeaka Sabkha”, Bardawil Lagoon, north coast of the Sinai. 16S rRNA gene metabarcoding generated a total of 488,828 reads from both sites, grouped into 17,741 operational taxonomic units (OTUs). 3030 OTUs were shared in both sites, while 2255 and 9426 OTUs were unique to Aghormy Lake and Sebeaka Sabkha, respectively. Both sites showed an abundance of Bacteroidetes, particularly the genera Salisaeta and Salinibacter in Aghormy and Sebeaka Sabkha, respectively. Aghormy brine was characterized by phylotypes belonging to Deinococcus-Thermus, Spirochaetes, Rhodovibrio, Piscirickettsiaceae and GMD14H09 (Deltaproteobacteria). While phylotypes assigned to AT12OctB3 (Bacteroidetes), Rhodobacteriaceae, Ectothiorhodospiraceae, and Xanthomonadaceae formed Sebeaka Sabkha bacterial community. A Cyanobacteria-like phylotype was assigned to genus Dactylococcopsis in both brines. The archaeal family, Halobacteriaceae, represented 4.8% of Sebeaka brine reads. Although some of the recorded phylotypes in both brines belonged to the same phyla, they differed in lower taxonomic ranks, implicating distant brine environments' impact on shaping halophilic communities. The metabolic prediction analyses showed a dominance of TCA cycle, branched amino acid biosynthesis and heme biosynthesis, common metabolic features for salt tolerance.

Growth and mortality studies on fish are considered crucial to the comprehension of species biology and population dynamics. This work aims to study the growth and mortality of Merluccius merluccius (Linnaeus, 1758) from the North Atlantic coasts of Morocco. A total of 1001 European hakes was sampled from trawler’s fishery during the period from August 2017 to August 2018. Growth parameters were computed for the European hake males and females by applying the von Bertalanffy growth formula. The asymptotic lengths (L∞), growth coefficients (k) and the theoretical age at zero-length (t₀) for females and males were; L∞ = 80.19 cm, k = 0.27 year⁻¹, t₀ = –0.472 year⁻¹, and L∞ = 69.15 cm, k = 0.31 year⁻¹, t₀ = –0.426 year⁻¹, respectively. The total mortality rate (Z), natural (M) and fishing mortality (F) were estimated as Z = 1.49, M = 0.51 and F = 0.98 for combined sexes. The estimated exploitation ratio (E = 0.66), indicated overexploitation of the M. merluccius in the North Atlantic coasts of Morocco.

The present review is detailed on the microplastics occurrences and their size, types besides impacts of microplastics from phytoplankton to marine mammals. Hence, the previous studies stated that the impacts of microplastics in the marine environment have been compared with the interaction of microplastics into marine organisms such as primary and secondary producers, fish, crustaceans, molluscs, sponges, marine plants, coral reefs, marine mammals and humans. Lastly, there is a need to understand the ecotoxicological effects of environmentally relevant concentrations of microplastics on the health of aquatic organisms. The recycling and reuse of plastic products and the support for research and innovation to develop new products to replace single-use plastics are also necessary to prevent and reduce plastic pollution. Thus, a precautionary approach is urged to be considered and research supporting mitigation of plastic pollution should be prioritized by the policy makers.

Our study considers the influence of a different electrode shape on the removal percentage of Reactive Yellow 17 (RY17) dye. The anode is a PVC tube with an iron net wrapped around the tube with a surface area of 95.88 cm², while the cathode is a stainless-steel tube with a surface area of 118.2 cm² for each cathode. Many factors were taken into account like pH, current density (CD), effect of supporting electrolytes and the effect of temperature. Under optimum conditions, the removal efficiency has reached 99.8%. The thermodynamic parameters showed the spontaneity of the mechanism of removal. The energy consumption and cost of operation were 21.7 kWh/kg dye and 1.115 US$/m³, respectively.

Penaeus latisulcatus (Kishinouye, 1896) is considered one of the most economically important penaeid shrimp species in the Egyptian Red Sea. Recently, it appeared in the Egyptian Mediterranean catches. The present study is concerned with the estimation of growth, age and population characteristics of the non-indigenous P. latisulcatus collected between the months of July 2020 to June 2021 from the landing fishing center of Boughaz El-Maadiyah (Egyptian Mediterranean coast). A total of 2214 individuals were collected monthly. The results showed that the females to males ratio was 1:0.98. According to the Chi-square test, there was no statistically significant difference between the sexes (X² = 0.181, df = 1, P > 0.05). The distribution of the length frequency showed that the females varied from 5.0 cm to 19.2 cm (TL) with a mean length of 11.73 ± 2.78 cm, while the males ranged from 5.3 cm to 17.1 cm (TL) with a mean length of 10.97 ± 2.06 cm. Positive allometry was detected for the total length-total weight relationship. The parameters of von Bertalanffy were L∞ = 20.56 cm, K = 0.99 yr⁻¹ and t_o = −0.178 yr⁻¹ for females, L∞ = 18.68 cm, K = 1.05 yr⁻¹ and t_o = −0.172 yr⁻¹ for males, and L∞ = 20.74 cm, K = 0.90 yr⁻¹ and t_o = −0.196 yr⁻¹ for the combined sexes. The expected age of females and males were 2.6 and 2.2 years, respectively. According to the parameters obtained, the current exploitation rate of the population of P. latisulcatus was estimated at Ecur. = 0.59. The results indicated that the population of P. latisulcatus is being highly exploited in Boughaz El-Maadiyah landing center (Egyptian Mediterranean coast). Hence, it is important to manage the P. latisulcatus shrimp resources in the studied area. Furthermore, similar studies are recommended for P. latisulcatus along the Egyptian Mediterranean coast to evaluate variations between populations in different fishing areas. Moreover, further studies are needed about the new aspects of the reproductive activity of this species as well as its aquaculture to estimate its growth rate experimentally.

The water quality of Bardawil Lake and its fisheries significantly deteriorated resulting in a steady decrease in the available fish catch. The Lake is of importance to the local indigenous population, who rely on it for practically all their income in this arid area. Over 5,000 fishermen representing 5,000 families from all the cities of North Sinai Governorate operate in the Lake, which serves nearly half of the governorate's population. Some restricted agricultural recovered land that has been planted with olives, peaches, watermelons, and dates is another source of revenue. Overfishing has also resulted in further fish population declines. However, we can resolve these problems by Lake's restoration. New physical interventions can aid in the restoration of the marine ecology and fish population of the Lake. The principal strategy for enhancing the Lake's environmental characteristics is to improve water exchange with the Mediterranean Sea by stimulating tidal action. Deepening existing inlets, in combination with other Lake-designated sites, will result in a considerable increase in fish population, which will be noticeable in the first year after the restoration operations and will continue to grow over time. The interest of the Egyptian leadership in the Bardawil Lake project, in complementarity with the Sinai development strategy, will contribute to increasing the productivity of the fisheries in the Lake and provide direct and indirect job opportunities for Egyptian citizen.

A study on the advantages of liming combined to sedimentation-dredging to reduce heavy metals and metalloid in coal mining water was performed in tailing wastewater sedimentation ponds, mixed water sedimentation ponds, and Sangatta River where water from the coal mining area flows in. The concentrations of heavy metals and metalloid showed that the results were not significantly different (P > 0.05) between water from ponds or reservoirs of coal mining and water in the Sangatta River. The liming combined to sedimentation and the followed regular dredging of the sediment was useful in reducing the metals and metalloid in water from the coal mining area before being released into the public water.

The study aims to determine the growth performance and economic viability of the dietary supplementation of camote i.e., Ipomoea batatas L. powder and extracts in the diets of the Nile tilapia. The fish were reared in twelve 1 m³ hapa nets installed in a 500 m² pond. Four groups of fish were used in the experiment; the control group was fed with formulated practical diets (PD), and diets supplemented with either camote shoot powder (PD + CSP), hot-water extract (PD + CSHWE), and crude ethanol extract (PD + CSCEE). The feeding trial lasted 12 weeks. The weight gain (WG), feed conversion ratio (FCR), feed efficiency ratio (FER), protein efficiency ratio (PER), specific growth rate (SGR), and condition factor (CF) were studied. The economic viability was determined through the cost of production, gross profit, cost-and-return, and profitability analyses. The fish fed with PD + CSHWE exhibited improved growth performance as evidenced by an increase in WG, FER, PER, SGR, and CF, while showing low values of FCR. The economic analyses also revealed that PD + CSHWE was the most economically feasible diet based on the cost of production, gross profit, cost-and-return, and profitability analyses. The study had proven that the incorporation of CSHWE in practical diets could improve the growth performance and increase profitability if used for tilapia culture.