Egyptian Journal of Aquatic Research最新文献

Crude and α- and β-cellulose yields were estimated in six macroalgal species belonging to various groups growing in the Mediterranean coast, Egypt. The extracted cellulose yield varied between 11.70% dry weight (DW) for Colpomenia sinuosa and 1.38% DW for Jania rubens. The results revealed that α-cellulose represented the major proportion “43%” to “74%” of cellulose, while β–cellulose represented the minor proportion “2.3%” to “12%”. Cellulose nanofibers (CNFs) were prepared from crude cellulose via acid hydrolysis, and the yield was calculated as “47.74%” to “9.13%”. The seaweed cellulose and CNFs of the maximum-producing species were morphologically characterized via scanning electron microscopy (SEM). The shapes of the extracted cellulose ranged from filaments and plates to web-like structures according to the seaweed species and cellulose fractions. The CNFs exhibited nanosphere shapes, with the average size ranging from 14.94 to 30.82 nm. Chemical analysis of the prepared cellulose performed via Fourier-transform infrared spectrometry (FTIR) demonstrated the similarity between crude and α- and β-cellulose. The CNFs were investigated via Ultraviolet–visible spectroscopy and surface plasmon resonance (SPR) bands, which confirmed the spherical shape of the prepared CNFs. In conclusion, the selected seaweeds can be used as a renewable source of dietary fibers and CNFs with economic applications. Further studies are required to screen numerous species of seaweeds for large-scale production of cellulose.

The Red Sea is a rich ecosystem with thousands of species containing a variety of bioactive compounds that have potential pharmacological applications. This study will highlight the potential importance of sea urchins and jellyfish extracts. The gas chromatography-mass spectrometry (GC–MS) revealed many phenolic compounds in the extracts of the sea urchin (Diadema savignyi) and jellyfish (Aurelia aurita). The extracts were also tested for their potential radical scavenging activity as well as their safety and toxicity in vitro and in vivo. Both extracts showed significant total antioxidant capacity (P-value < 0.0001), and free radical scavenging activity (DPPH) compared to ascorbic acid and butylated hydroxyanisole (BHA, P-value < 0.0001). They were found to be safe in vitro and enhanced cell proliferation of fibroblast cells (L929) (P-value < 0.0001), and neuronal cell lines (neuroblastoma SH-SY5Y) (P-value < 0.0001).

Intraperitoneal administration of both extracts did not show any significant morbidity within tested concentrations. Liver enzymes (ALT and AST) and renal functions showed no significant changes compared to control. No significant histological changes in the liver or kidney tissues were observed. The current study proved the safety of both sea urchins and jellyfish extracts in vitro and in vivo, which paves the way for further studies on the biomedical application of both extracts in areas of neuroprotection and cancer treatment.

Sediment textural variability and distributions of one hundred sediments samples across three major strategic Harbours, Quseir, Safaga, and Hurghada, along the Northern Red Sea have been assessed. Grain size parameters and cluster analysis have been applied to reveal indices of the marine environment, mainly the energy and hydrodynamic conditions, which controlled the mode of transportation and depositional settings. The three Harbours exhibited shallow marine environment, corresponding to siliclastic terrigenous flux, associated with carbonate sediments, which sustained biogenic fragments nearby reef and mangrove sites. Depositional settings were controlled by bottom topography, sediments sources, water depth, and closeness from shoreline. This was also coupled with the exposure degree to anthropogenic discharges that triggered sediment texture disturbance and impacted seabed habitat of Safaga Harbour. The latter is more affected by contamination than Quseir and Hurghada Harbours as its topography favored the accumulation of contaminants and acted as pollutant-traps. The C-M pattern suggested rolling as the main mode of nearshore sediments transportations across the three Harbours. Suspension transportation was recognized in Quseir Harbour with higher ratio compared with Safaga Harbour, while it was absent in Hurghada Harbour. Nevertheless, the investigated Harbours shared some common features, particularly low-energy hydrodynamic regime corresponding to their semi-isolated locations and arid climatic conditions, which ruled sediments texture and distributions.

Since their earliest history, benthic foraminifers have diversified to inhabit a vast array of habitats, from semi-terrestrial to the deep-sea floor. Epiphytic foraminifers developed morphologies that have allowed them to inhabit macroalgal fronds and thalli. This study examined the presence of benthic foraminiferal species living on algal species inhabiting rocky coastal environments in the southeastern Mediterranean Sea. Fronds of six algal taxa found abundantly on a carbonate wave-cut platform off the east coast of Alexandria were collected and the associated foraminifers living on each frond were identified. Twenty foraminiferal species were recorded, with seven epiphytic species (Asterigerinata mamilla, Elphidium aculeatum, Elphidium crispum, Peneroplis pertusus, Peneroplis planatus, Rosalina bradyi, and Rosalina macropora) comprising > 80% of the assemblage. Nearly 70% of the foraminiferal specimens were found on two algal species, Caulerpa racemosa and Ellisolandia elongata. Two Indo-Pacific foraminiferal species found in the samples (Amphistegina lobifera and Amphisorus hemprichii), in addition to Caulerpa racemosa, are considered invasive species in the Mediterranean. The widespread occurrence of the opportunistic invasive Caulerpa spp., which apparently provides suitable habitat for many epiphytic foraminifers, may partially compensate for the predicted decline in coralline-algal habitat under the effect of ocean acidification.

The morphological description of the dinoflagellate Prorocentrum micans, based on light and SEM microscopy, population dynamics, environmental drivers and seasonal abundance fluctuations were recorded in Qarun Lake during different seasons during the period from 2018 to 2019. The highest bloom of P. micans was observed in summer and autumn, but it declined in winter. This blooming was highly correlated to the increased water salinity and temperature. The seasonal cellular changes included partial deterioration of the cytoplasmic organelles that was observed in autumn, and many ruptured individuals with chlorophyll leakage in winter. As for the cellular proteins, many polypeptides were significantly down-regulated downstream from summer to winter. Induction of protein phosphorylation steady state was found in winter samples. This most likely contributed to signal transduction cascades regulating programmed cell death and abundance of the fluctuations of P. micans during seasonal changes. The proteomic study provided insights into the population dynamics and the ecological drivers of P. micans.

Aspergillus flavus, an amylase-producing fungus, was isolated from the Mediterranean Sea, Alexandria, Egypt. It was selected according to the formation of a clear zone using the Dox-medium containing 1% starch for enzyme production. The maximum amount obtained of amylase production was 22.68 U/mL after 7 days of incubation under static condition. Partially purified amylase with 70% ethanol provoked a single protein band with 54 kDa molecular weight using SDS-PAGE giving a specific activity of 307.35 U/mg. The purified α-amylase exhibited optimal activity of 65.17 and 71.5 U/mL at pH = 6 and 50 °C, respectively. The calculated enzyme kinetics were K_m = 5 mg/mL and V_max = 100 U/mL. Residual α-amylase retained optimum stability at 50 °C by 67.74% and at pH = 6 by 100% after 60 min of incubation. The highest enzyme tolerance occurred at 1.5 mM NaCl concentration. The highest enzyme yield (165.24 U/mL) was provided by the immobilized amylase with 1% of covalent bonding agents solution, providing double the sugars’ byproduct than from the free amylase form, and double the bioethanol fermentation yield with 0.12 g/g sugar/l. Highly specific activity of such enzyme in the immobilized form could offer a highly effective approach for bioethanol production on the industrial scale than the free and other reported forms.

One of the dilemmas that researchers face when applying the Penman equation (1948) is that it requires significant meteorological data that are not readily available at the standard meteorological stations. Therefore, many researchers have worked hard to devise several simplified algebraic equations that are equivalent to the standard Penman equation to calculate evaporation quantities with accuracy from the available data. In this study, the Penman equation, which is a reference method, was applied in addition to four other simplified methods. Notably, one method of the simplified methods did not require wind speed data. To calculate the evaporation quantities by analyzing the daily averages along the Egyptian Mediterranean Coast (Mersa Matruh, Alexandria and Port Said) for a period of ten years from 2007 to 2016, several statistical methods have been applied to assess and evaluate the performance and suitability of these simplified methods. It was clear from the results obtained that two of these simplified methods are of good efficiency when compared to the standard Penman equation, whereas, the third method is only valid for moderate or low wind speeds (< = 3 m/s). The results of the fourth method indicated that it was not suitable for application in the study area.

In order to monitor the ecological status of the largest Egyptian northern drains, an environmental comparison is performed between Bahr El Baqar Drain and Hadous Drain based on water quality and the community composition of their phytoplankton groups to assess the environmental hazard impacts on Lake Manzala. From both drains during the period 2015–2020 (5 years average), fourteen parameters were seasonally recorded; Hydrogen Ion, biological oxygen demand, chemical oxygen demand, electric conductivity, total suspended solids, total dissolved solids, bicarbonates, cations and anions (nitrates, sulfates, Calcium, Sodium, Potassium, Magnesium and Chloride), as well as seven heavy metal parameters (Copper, Iron, Manganese, Nickel, Lead, Boron, and Zinc). Statistically, phytoplankton seasonal dominance and abundance, diversity indices, species richness, evenness, Shannon and Simpson indices, and Pearson correlation were statistically calculated. The results showed that the average values of pH, HCO₃, BOD, COD, EC, TSS, TDS, NO₃, anions and cations in Bahr El Baqar Drain were higher than those in Hadous Drain. Phytoplankton groups in both drains belonged to five major groups with a descending order of dominance; Cyanophyta > Chlorophyta > Bacillariophyta > Euglenophyta > Dinophyta. Bicarbonates positively correlated with Chlorophyceae (evenness = 0.871, Shannon = 2.029), Cyanophyceae (1.964, 0.853), Euglenophycea (0.857, 1.535), and Dinophyceae (0.836, 0.918). BOD and COD positively correlated with Nitzschia sp., Euglena velata, and Peridinium volzii, and negatively correlated with Amphora sp., Euglena viridis, and Ceratium hirundinella. Chlorophyceae correlated positively with K, Mg, Cl, SO₄ and NO₃. Cyanophyceae correlated negatively with K, Mg, Na, B, Cl and SO₄. Bacillariophycea positively correlated with Ni and NO₃. Dinophyceae negatively correlated with Cl and SO₄. Phytoplankton species expressed different dominance, diversity indices and statistical correlation with each water quality parameter, which reflected the selectivity and growth manners of algae. From the former mentioned results, it was concluded that the phytoplankton groups are very sensitive and useful indicator of the health status of any water stream. Concerning the bad quality of water in Bahr El Baqar Drain and Hadous Drain, management plan should be implemented for both drains, in particularly Bahr El Baqar Drain, to preserve the environmental status of Lake Manzala.

The present work is a biodiversity study on some caprellids from the Northern Red Sea coast with their occurrence and distribution in different habitats in relation to water depth. From late 2019 to early 2020, a total of 67 individuals were collected from Hurghada and Shalateen, Red Sea coast by snorkeling and SCUBA diving, from five different depths (0.5, 5, 15, 25, and 35 m). A total of 7 caprellid species belonging to six genera and two subfamilies were recorded from Hurghada site, and only 5 species were recorded from Shalateen site. Phtisica marina Slabber, 1769, Metaprotella sp., and Deutella sp. were recorded for the first time from the Red Sea waters. These new records are significant in terms of increasing the known species diversity of the Red Sea fauna. Paradeutella multispinosa was the most abundant caprellid and was represented by 46.3% at Shalateen, followed by Hemiaegina minuta (31.7%) at Shalateen and (50.0%) at Hurghada. SIMPER analysis showed that the caprellids, P. multispinosa, H. minuta and P. marina, were the most contributing species to the dissimilarity between the two studied sites. Depth and habitat composition directly influenced the total caprellid abundance and diversity at both sites.

The present quasi-experimental research investigated the growth ability and removal efficiency of Hydrilla verticillata in freshwater from Nong Han Lake (NHL), domestic wastewater from constructed wetlands (CW) and wastewater from university canteen wastewater (UCW) in Sakon Nakhon, a north-east province in Thailand. The growth rate was measured by evaluating the fresh mass of H. verticillata and comparing the removal efficiency of the biochemical oxygen demand (BOD), the chemical oxygen demand (COD) and phosphate at the hydraulic retention time on days 7, 14, 21 and 28. The efficiency of BOD removal of H. verticillata in UCW, NHL and CW was 26, 80 and 84%, respectively, whereas the COD removal efficiency was 25, 72 and 63%, respectively, and that of phosphate was 6, 44 and 87%, respectively. No difference was found in growth rates between H. verticillata from NHL and CW. Further, CW provided a good growth rate of H. verticillata, and the domestic wastewater discharges could provide a rapid growth of H. verticillata. Finally, H. verticillata might be used in aquatic ecosystems.