Red Sea Environment Research Articles

Effect of Heat Treatment and Ceria Coating on the Degradation Behavior of 7075 Al/B4C Composite in Red Sea Environment

Effect of Heat Treatment and Ceria Coating on the Degradation Behavior of 7075 Al/B4C Composite in Red Sea Environment

Large Individual-Level Variability in Diel Activity and Depth Use for the Common Lionfish (Pterois miles)

The common lionfish, Pterois miles, a notoriously invasive species known for its harmful effect on native fish communities in the Atlantic Ocean, has recently begun spreading across the Mediterranean Sea. The wide niche breadth of the lionfish has been hypothesized to facilitate its invasion success. However, it is unclear to what extent this wide niche-breadth is associated with individual-level variation and repeatable behavior over time. Large individual-level behavioral variations may allow individuals to adapt quickly to local conditions, increasing the species’ chance of invasion success and complicating mitigation efforts. In this study, we used an acoustic telemetry system in P. miles’ native Red Sea environment to explore individual-level variation in depth preference and diel activity. A wide depth range may indicate an ability to tolerate a variety of biotic and abiotic conditions, and variability in diel activity may indicate an ability to exploit multiple diet sources. We found large individual-level variability in P. miles’ activity hours; although all tracked fish were active during both sunrise and sunset, certain individuals had prolonged activity hours to variable extents. Moreover, individuals often change their patterns over time, showing low repeatability. We also found that individuals had different depth preferences and commuted between shallow and deep waters over short periods of time. This study is one of the first to explore diel activity as an individual-level trait in wild fish. The variability found in depth and diel activity is likely one of the reasons P. miles has been so successful in invading the Mediterranean Sea. In addition, this variability may impact mitigation efforts within the Mediterranean Sea as nocturnal individuals from deeper waters might replenish diurnally culled shallow-water populations.

Genome sequencing and identification of cellulase genes in Bacillus paralicheniformis strains from the Red Sea

BackgroundCellulolytic microorganisms are considered a key player in the degradation of plant biomass in various environments. These microorganisms can be isolated from various environments, such as soils, the insect gut, the mammalian rumen and oceans. The Red Sea exhibits a unique environment in terms of presenting a high seawater temperature, high salinity, low nutrient levels and high biodiversity. However, there is little information regarding cellulase genes in the Red Sea environment. This study aimed to examine whether the Red Sea can be a resource for the bioprospecting of microbial cellulases by isolating cellulase-producing microorganisms from the Red Sea environment and characterizing cellulase genes.ResultsThree bacterial strains were successfully isolated from the plankton fraction and the surface of seagrass. The isolated strains were identified as Bacillus paralicheniformis and showed strong cellulase activity. These results suggested that these three isolates secreted active cellulases. By whole genome sequencing, we found 10 cellulase genes from the three isolates. We compared the expression of these cellulase genes under cellulase-inducing and non-inducing conditions and found that most of the cellulase genes were generally upregulated during cellulolysis in the isolates. Our operon structure analysis also showed that cellulase genes form operons with genes involved in various kinds of cellular reactions, such as protein metabolism, which suggests the existence of crosstalk between cellulolysis and other metabolic pathways in the bacterial isolates. These results suggest that multiple cellulases are playing important roles in cellulolysis.ConclusionsOur study reports the isolation and characterization of cellulase-producing bacteria from the Red Sea. Our whole-genome sequencing classified our three isolates as Bacillus paralicheniformis, and we revealed the presence of ten cellulase orthologues in each of three isolates’ genomes. Our comparative expression analysis also identified that most of the cellulase genes were upregulated under the inducing conditions in general. Although cellulases have been roughly classified into three enzyme groups of beta-glucosidase, endo-β-1,4-glucanase and exoglucanase, these findings suggest the importance to consider microbial cellulolysis as a more complex reaction with various kinds of cellulase enzymes.

Bioactive marine metabolites derived from the Persian Gulf compared to the Red Sea: similar environments and wide gap in drug discovery.

Marine life has provided mankind with unique and extraordinary chemical structures and scaffolds with potent biological activities. Many organisms and secondary metabolites derived from fungi and symbionts are found to be more environmentally friendly to study than the marine corals per se. Marine symbionts such as Aspergillus sp., a fungus, which can be isolated and grown in the lab would be a potential and continuous source of bioactive natural compounds without affecting the marine environment. The Red Sea is known for its biodiversity and is well-studied in terms of its marine-derived bioactive metabolites. The harsh environmental conditions lead to the development of unique metabolic pathways. This, in turn, results in enhanced synthesis and release of toxic and bioactive chemicals. Interestingly, the Persian Gulf and the Gulf of Oman carry a variety of environmental stresses, some of which are similar to the Red Sea. When compared to the Red Sea, the Persian Gulf has been shown to be rich in marine fungi as well, and is, therefore, expected to contain elaborate and interesting bioactive compounds. Such compounds may or may not be similar to the ones isolated from the Red Sea environment. Astoundingly, there are a very limited number of studies on the bioactive portfolio of marine-derived metabolites from the Persian Gulf and the Gulf of Oman. In this perspective, we are looking at the Red Sea as a comparator marine environment and bioactive materials repertoire to provide a futuristic perspective on the potential of the understudied and possibly overlooked bioactive metabolites derived from the marine life of the Persian Gulf and the Gulf of Oman despite its proven biodiversity and harsher environmental stress.

A Review of Heavy Metals in Coastal Surface Sediments from the Red Sea: Health-Ecological Risk Assessments.

The heavy metal (HM) pollution in sediment is of serious concern, particularly in the Red Sea environment. This study aimed to review and compile data on the concentrations of four HMs (Cd, Cu, Pb, and Zn) in the coastal surface sediments from the Red Sea, mainly from Saudi Arabia, Egypt, and Yemen, published in the literature from 1992 to 2021. The coastal sediments included those from mangrove, estuaries, and intertidal ecosystems. It was found that the mean values of Cd, Cu, Pb, and Zn in coastal Red Sea sediments were elevated and localized in high human activity sites in comparison to the earth upper continental crust and to reference values for marine sediments. From the potential ecological risk index (PERI) aspect, 32 reports (47.1%) were categorized as ‘considerable ecological risk’ and 23 reports (33.8%) as ‘very high ecological risk’. From the human health risk assessment (HHRA) aspect, the non-carcinogenic risk (NCR) values (HI values < 1.0) of Cd, Cu, Pb, and Zn represented no NCR for the ingestion and the dermal contact routes for sediments from the Red Sea countries. The reassessment of the HM data cited in the literature allowed integrative and accurate comparisons of the PERI and HHRA data, which would be useful in the management and sustainable development of the Red Sea area, besides being a helpful database for future use. This warrants extensive and continuous monitoring studies to understand the current and the projected HM pollution situation and to propose possible protective and conservative measures in the future for the resource-rich Red Sea ecosystem.

Topographical responses of defense grade 7075 Al/TiO2 composite in Red sea environment

7075 Al/TiO2 composite is one among the promising materials with tailor made properties for structural applications in defense industry. In order to achieve superior mechanical properties, these composites are subjected to aging treatment which in turn give rise to an adverse effect on the degradation behaviour of the composite in aggressive environments. One of the major concerns in defense applications is the corrosion related problems. Hence this work concentrates on the investigation of the corrosion behaviour of the artificially aged composite using potentiodynamic polarization and gravimetric analysis. Both techniques show a similar trend in corrosion behaviour of the composite in Red sea environment. Artificial aging treatment (T6) is carried out prior to the corrosion tests. Based on the hardness variations, the composite specimens were classified into three categories namely peak aged, under aged and over aged. Among the three groups of specimens, the peak aged composite exhibits higher degradation behavior in Red sea water when compared to that of under aged and over aged composite specimens.

Nutritional value and bioaccumulation of heavy metals in muscle tissues of five commercially important marine fish species from the Red Sea.

The study evaluated the nutritional quality and investigated the heavy metals concentration in muscle tissues of five commercially important marine fish species, including brownspotted grouper (Epinephelus chlorostigma), squaretail coralgrouper (Plectropomus areolatus), black pomfret (Parastromateus niger), goldbanded jobfish (Pristipomoides multidens), and blueskin seabream (Polysteganus coeruleopunctatus) from the Red Sea, Jeddah Coast, Saudi Arabia. Significant differences (p < 0.05) were observed in the proximate chemical composition of fish muscles in these species. The highest protein content (17.66 ± 0.58%) was achieved in blueskin seabream while the lowest (15.28 ± 0.46%) was observed in brownspotted grouper. The highest lipid content (2.97 ± 0.45%) was recorded in squaretail coralgrouper while the lowest (1.52 ± 0.26%) was observed in blueskin seabream. Heavy metal concentrations varied significantly within and between fish species under study (p < 0.05). Significant differences in the concentration of heavy metals among fish species were recorded. Results revealed that the bioaccumulation of Cr, Fe, Ni, and Cd in muscles of fish species under study was higher than the standard concentration, but that of Mn, Cu, and Pb were less than the standard concentration recommended in the EU, FAO, and WHO guidelines. In conclusion, these fish species represent a high-quality food source but is unsafe due to the level of certain minerals in their tissues. Results also indicated that the Red Sea environment is contaminated with heavy metals, which was reflected in the tissues of fishes used in this study.

Status analysis of the Red Sea fisheries in the Kingdom of Saudi Arabia

The Red Sea is a unique marine ecosystem and Saudi Arabia's coastline has the longest portion. The Red Sea ecosystem off Saudi Arabia's coast is characterized by vibrant nature that is populated by many forms of marine life and more than a third of known fish species spend part or all of their lives in coral reef habitat. Saudi Arabia's fishing fleet has recently developed and diversified the methods. Large fishing vessels such as trawling and purse seine have been engaged in fishing at the Red Sea, along with artisanal fishing, resulting in increased pressure on fish stocks. The fishing fleet operating in the Saudi Red Sea has increased substantially since 1996, in comparison, fish catch has not increased. Government endeavours to monitor and track fishing activities to reduce the depletion of stocks. Industrial development, human activity, and urban expansion affect the Red Sea environment significantly. The timely detection and control of pollution emissions also decrease its impacts on the Red Sea ecosystem. Finally, the Saudi coastal Red Sea fisheries need a lot of serious research to provide information and data that contribute to their natural resource sustainability.

Investigation on the Effect of Thermal and Mechanical Treatment to the Offshore Corrosion Behavior of 6351 Aluminum Alloy in Red Sea Environments.

This study investigates the effect of artificial aging treatment and mechanical attrition treatment on the corrosion behavior of 6351 Al alloy in Red Sea environment. The artificial aging of the alloy is carried out at temperature range 140°C–240°C in steps of 20°C for various time periods after the solution heat treatment at 530°C for 1 hour. Based on the hardness measurements, the aged specimens are categorized into three, namely, underaged, peak aged, and overaged. The as received alloy specimens are subjected to mechanical attrition treatment in a vacuum chamber using steel balls. Vickers hardness test reveals that there is a remarkable improvement in hardness of mechanical attrition treated specimens compared to that of aged specimens. The aged and mechanical attrition treated specimens were subjected to the corrosion test in Red Sea water using the Autolab instrument. The corrosion tests reveal that the peak-aged composite corrodes more in Red Sea water when compared to that of other groups of specimens. XRD measurements and SEM analysis are carried out to study the surface nature of attrition treated specimens. It is observed that the mechanical attrition treated specimens exhibit a nanocrystalline surface and lead to a decrease in corrosion resistance. However, the annealing of the alloy after attrition treatment optimizes the mechanical and corrosion properties of the alloy.

Draft genome of an iconic Red Sea reef fish, the blacktail butterflyfish (Chaetodon austriacus): current status and its characteristics.

Butterflyfish are among the most iconic of the coral reef fishes and represent a model system to study general questions of biogeography, evolution and population genetics. We assembled and annotated the genome sequence of the blacktail butterflyfish (Chaetodon austriacus), an Arabian region endemic species that is reliant on coral reefs for food and shelter. Using available bony fish (superclass Osteichthyes) genomes as a reference, a total of 28926 high-quality protein-coding genes were predicted from 13967 assembled scaffolds. The quality and completeness of the draft genome of C.austriacus suggest that it has the potential to serve as a resource for studies on the co-evolution of reef fish adaptations to the unique Red Sea environment, as well as a comparison of gene sequences between closely related congeneric species of butterflyfish distributed more broadly across the tropical Indo-Pacific.

Metagenomic covariation along densely sampled environmental gradients in the Red Sea.

Oceanic microbial diversity covaries with physicochemical parameters. Temperature, for example, explains approximately half of global variation in surface taxonomic abundance. It is unknown, however, whether covariation patterns hold over narrower parameter gradients and spatial scales, and extending to mesopelagic depths. We collected and sequenced 45 epipelagic and mesopelagic microbial metagenomes on a meridional transect through the eastern Red Sea. We asked which environmental parameters explain the most variation in relative abundances of taxonomic groups, gene ortholog groups, and pathways-at a spatial scale of <2000 km, along narrow but well-defined latitudinal and depth-dependent gradients. We also asked how microbes are adapted to gradients and extremes in irradiance, temperature, salinity, and nutrients, examining the responses of individual gene ortholog groups to these parameters. Functional and taxonomic metrics were equally well explained (75-79%) by environmental parameters. However, only functional and not taxonomic covariation patterns were conserved when comparing with an intruding water mass with different physicochemical properties. Temperature explained the most variation in each metric, followed by nitrate, chlorophyll, phosphate, and salinity. That nitrate explained more variation than phosphate suggested nitrogen limitation, consistent with low surface N:P ratios. Covariation of gene ortholog groups with environmental parameters revealed patterns of functional adaptation to the challenging Red Sea environment: high irradiance, temperature, salinity, and low nutrients. Nutrient-acquisition gene ortholog groups were anti-correlated with concentrations of their respective nutrient species, recapturing trends previously observed across much larger distances and environmental gradients. This dataset of metagenomic covariation along densely sampled environmental gradients includes online data exploration supplements, serving as a community resource for marine microbial ecology.

English

The present study was carried out to isolate, purify and elucidate the structure of low molecular weight bioactive compounds from sea anemone, Gyrostoma helianthus of the Red Sea environment. The obtained results indicated that the ethanolic crude extract of the sea anemone, G. helianthus showed inhibition activity against acetylcholinesterase (AchE). The 0.5 kD fraction inhibited the activity of the AchE that indicated the presence of low M.W active compound(s) of less than 0.5 kD. Two active fractions were obtained after BioGel P2 fractionation of the 0.5 kD of the G. helianthus. The first active fraction inhibited the activity of the acetylcholinesterase, while the other fraction did not. High-performance liquid chromatography (HPLC) technique aided by semipreparative columns was used to isolate the target compounds in a pure form for the structure elucidation, one dimensional nuclear magnetic resonance (NMR) analysis (1H and 13C-NMR) and DEPT were carried out to elucidate the structure of the isolated compound which was tentatively identified as N,N'-bis-(1-methyl-pyridin-2-yl)-hydrazine. Key words: Sea anemone, Gyrostoma helianthus, Red Sea, structure elucidation, acetylcholinesterase (AchE) inhibitor.

Evaluation of poly-aromatic hydrocarbons (PAHs) in the aquatic species of Suez Gulf water along El-Sokhna area to the Suez refineries

The Egyptian Red Sea environment especially along El-Sokhna area to the Suez refineries (Suez) is severely contaminated with organic compounds, as well as overfishing. This may be well contributory to recent serious declines in fish stocks. Fish embryos are also particularly vulnerable to oil exposure, even at extremely low concentrations of less than one part per billion. Consequently, even traces of oil pollution at levels often considered safe for wildlife can cause severe damage to fish. Sixteen polycyclic aromatic hydrocarbons (PAHs) were investigated in ten fish species of aquatic species by high performance liquid chromatography (HPLC). The compositions of PAHs determined in all samples were measured in order to use them as chemical markers for identifying different sources of PAH pollutants in the studied region. The total content of these16 PAHs ranged from 399.616 up to 67,631.779ng/g wet weight. The data show that these values are considered to be alarmingly high enough to cause lethal toxicity effect by accumulation. All studied aquatic species samples are characterized by relatively high concentrations of the six-membered ring PAHs. The origin of PAHs in the collected samples is either petrogenic, biogenic, or mixed petrogenic and biogenic.

Supply-side approaches to the economic valuation of coastal and marine habitat in the Red Sea

The degradation of natural fish habitat in the ocean implies lost economic benefits. These value losses often are not measured or anticipated fully, and therefore they are mainly ignored in decisions to develop the coast for industrial or residential purposes. In such circumstances, the ocean habitat and its associated ecosystem are treated as if they are worthless. Measures of actual or potential economic values generated by fisheries in commercial markets can be used to assess a conservative (lower-bound) value of ocean habitat. With this information, one can begin to compare the values of coastal developments to the values of foregone ocean habitat in order to help understand whether development would be justified economically. In this paper, we focus on the economic value associated with the harvesting of commercial fish stocks as a relevant case for the Saudi Arabian portion of the Red Sea. We describe first the conceptual basis behind supply-side approaches to economic valuation. Next we review the literature on the use of these methods for valuing ocean habitat. We provide an example based on recent research assessing the bioeconomic status of the traditional fisheries of the Red Sea in the Kingdom of Saudi Arabia (KSA). We estimate the economic value of ecosystem services provided by the KSA Red Sea coral reefs, finding that annual per-unit values supporting the traditional fisheries only are on the order of $7000/km2. Finally, we develop some recommendations for refining future applications of these methods to the Red Sea environment and for further research.

Plutonium isotopes in marine sediments and some biota from the Sudanese coast of the Red Sea

Measurements of (239+240)Pu and (238)Pu were carried out on marine biota as well as on sediments from the fringing reefs area extending towards north and south (Flamingo Bay) of PortSudan harbour. The analyses were performed using radiochemical separation and alpha spectrometry. The range of the activity concentrations in marine sediments, in mBq kg(-1) dry weight, was found to be from 5.10 to 82.00 for (239+240)Pu and from 0.89 to 8.63 for (238)Pu. Corresponding activity concentrations of (239+240)Pu and (238)Pu in sediments from the harbours at PortSudan and Sawakin were 53-301 and 8.29-28.6 (PortSudan) and 163-343 and 4.7 (Sawakin), respectively. The higher values for plutonium in marine algae suggest their suitability as an indicator species for monitoring purposes. The results obtained are generally lower than those found by other studies and show that the Red Sea environment is mildly affected by plutonium contamination. Activity ratios of plutonium isotopes confirm that the existence of plutonium in the Red Sea is mainly due to atmospheric global fallout.

The level of heavy metals in the the Red Sea after 50 years

A comparative study using a sequential separation scheme was done to investigate the metal pollution in the Red Sea environment. A seven step sequential separation technique was used in the analysis of surface sediments which had been collected during two expeditions. The first samples were collected during the Anglo-Egyptian ‘John Murry’ Expedition by R. Rs Mabahiss 1933–1934. The second expedition was a survey carried out by the Institute of Oceanography and Fisheries, Egypt, 1984. The heavy metals Co, Ni, V, Pb, Cu, Cd, Zn and major elements Fe and Mn were determined in each of the seven phases of the sediments. These phases were: (i) exchangeable; (ii) carbonates; (iii) easily reducible Mn and Fe oxides; (iv) humic and organic Fe Colloids; (v) resistant crystalline Fe, Mn oxides, residual organic matter and sulphides; and finally (vii) lattic held material (i.e. lithogenous). The Study has shown that the concentration of most of the heavy metals has increased over the last 50 years, due to natural pollution from hot brine pools or due to man made pollution from oil, heavy metals mining, discharge of domestic, industrial wastes and phosphate mining and transportation along the Red Sea Coastal areas.

Oil contamination in the Red sea environment

A survey of chronic oil pollution sources in the Red Sea and its gulves is given. The Red Sea is suffering from oil pollution along most of its coasts as well as in its offshore waters. Oil inputs from all sources in the Red Sea were estimated and compared with those in the world's oceans. While each km2 in the world's oceans receives 9.17 kg yr−1 of oil, each km2 in the Red Sea receives 14.61 kg yr−1. Oil inputs from refineries was also estimated for the Red Sea. It was found that each km2 of the Red Sea receives about 13 times the quantity received by each km2 in the world's oceans.

Implications of sea mining for the Red Sea environment

Implications of sea mining for the Red Sea environment

Impacts of mining on Central Red Sea environment

The mining of the Atlantis II deep will result in a significant input of heavy metals into the Red Sea. Quantities of dissolved compounds will result in major changes in the trace element composition of the water masses. The dissolution of minerals resulting in the release of toxic chemicals including zinc, copper, cadmium and mercury remains of fundamental concern which will require further study. The regime for discharge of tailings must be designed to minimise the dispersal of the solids, and also the fluids together with their dissolved leached constituents. If the discharges occur deep down the waste will be confined to the deep waters in the central graben, where the absence of significant upwelling combined with the natural chemical processes of removal via sorption will restrict the dispersal of the toxic substances. Research on biological activity within the epipelagic and mesopelagic zones has led to the recommendation that all wastes should be restricted to the bottom water below 1100 metres. A consideration of the likely effect upon benthos and water chemistry has demonstrated that tailings will have to be confined to the central graben, in order to protect local fisheries and the vulnerable reef and seabed environments of the coasts and the Central Trough. However, discharge of the tailings at depth would also limit the transmission of the tailing pollutants through the food web. It should, therefore, confine the effects of mining to a limited portion of the Red Sea biota. The shallower release of tailings within the zone of diel migration by plankton and nekton would expose a large community of organisms to the pollutants and result in the vertical transport of heavy metals up the water column.