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The Ayla Oasis in Aqaba, Jordan, is a major tourism and residential development project in Aqaba, Jordan, containing three artificial lagoons. This study explores the ecological sustainable development of Ayla Lagoons, focusing on the seawater and bottom sediment quality, and the bottom habitat, in addition to coral conservation and restoration initiatives. The flushing time, averaging 3.7 days for the Upper Lagoon and 2.4 days for the Middle Lagoon, plays a crucial role in maintaining water quality. These measures secure the well-being of all visitors and residents, while also preserving the marine biodiversity. The Upper, Middle, and Tidal Lagoons exhibit physiochemical properties in alignment with seawater characteristics of the Gulf of Aqaba. Sediment quality analysis shows organic carbon levels and grain size distribution vary among lagoons, indicating expected different energy conditions and a healthy environment. The lagoons support a diverse range of species, with a total of 2343 fish individuals belonging to 22 species across 17 families recorded. The comprehensive analysis of the Ayla Oasis lagoons' seawater and sediment quality revealed a dynamic and resilient ecosystem. Ayla's coral conservation and restoration initiative within its lagoons feature 166 reef balls, 5 coral nurseries, and 2 metal structures, all designed to foster marine biodiversity. The project demonstrates the effectiveness of Ayla Oasis' environmental resilience and monitoring strategies, showcasing a commitment to sustainable management and environmental stewardship. These efforts reflect Ayla's ongoing dedication to protecting and preserving the marine ecosystem, ensuring the long-term health of its coral reefs and surrounding marine life. [ABSTRACT FROM AUTHOR]

Hard corals are precious marine creatures that comprise a complex form of symbiosis between symbiont algae and coral holobiont. For decades, corals have been challenged by disastrous events of climatic and anthropogenic etiologies. Such complex interactions have resulted in devastating disease episodes among coral populations worldwide. There is a scarcity of information about diseases of hard corals in the Gulf of Aqaba, Red Sea, Egypt. Therefore, the current study aims to investigate various diseases of hard corals in this pristine habitat within the Red Sea. Whitening and dark green dots were the most noticeable morphopathology among hard coral samples collected from Gulf of Aqaba. Some human-based pathogens, such as Rothia kristinae, Cupriavidus pauculus, and Delftia acidovorans, were isolated from some of the examined coral tissues, while the Burkholderia cepacia group was isolated from the nearby sediment. The final identities of the above-mentioned bacterial isolates have been molecularly confirmed using 16S RNA sequence analysis. Pathologically, diseased corals have been observed with changes such as some forms of tissue losses, degenerative changes, and eosinophilic granular amoebocytes/agranular cells infiltration. The frequent detection of some microbial pathogens of human origin could suggest deleterious forms of environmental pollution of anthropogenic origin. Ultimately, the entire existence of hard coral populations is mostly threatened by swiftly erupting climatic changes as well as environmental aquatic pollution. Thus, the current study concludes the real need for extensive ecological, biological, pathological, and immunological studies to determine the eminent threats and propose possible control means for better/sustainable hard coral populations.

Scleractinian corals, the principal architects of coral reefs, face substantial threats from ongoing and anticipated climate change and other anthropogenic disturbances. This underscores the significance of investigating alternative reef-building organisms and their contribution to reefs' resilience. Among these alternatives, colonial hydrozoans of the genus Millepora, commonly called 'fire corals', play substantial roles in contributing to coral reef structure and functionality by depositing calcareous exoskeletons. Despite the ecological importance of fire corals, fundamental knowledge gaps remain regarding their biology and reproductive ecology. Here, we present a comprehensive study on the population dynamics, reproductive ecology, phenology, and sex ratio of the three Red Sea fire corals—Millepora dichotoma, M. exaesa, and M. platyphylla—in the Gulf of Aqaba and Eilat. The abundance of M. dichotoma and M. exaesa seems to have remained consistent over the last 50 years across two of the three depth zones surveyed, indicating their potential resistance or resilience. However, at the third depth surveyed, their abundance appears to have decreased. Our extensive in-situ monitoring of breeding events over six consecutive years has revealed a previously undetected relationship between Millepora species breeding events and the lunar cycle. Histological analyses indicated remarkably short reproductive cycles of only 2–3 weeks, recurring multiple times within a single season, in both M. dichotoma and M. exaesa, which is a unique reproductive aspect compared to other reef-building corals. These results highlight the high reproductive and resilience potential of Millepora species. Consequently, fire corals could assume a more substantial role as keystone species in changing environments and future reefs, emphasizing their importance in reef conservation and management. [ABSTRACT FROM AUTHOR]

Mangrove habitats are important ecosystems for their ecological value, and goods and services they offer. These costal habitats are currently vulnerable due to excessive human activities. The black mangrove Avicennia marina (Forssk.) Vierh. (Avicenniaceae) populations growing in Nabq protected area represents the northernmost latitudinal limit of the Indo-Pacific-East African naturally growing mangrove forests. In this study, nine A. marina populations inhabiting Gulf of Aqaba were studied to assess the genetic relationship among the populations by Start Codon Targeted (SCoT) and Inter Simple Sequence Repeat (ISSR) as DNA Markers. Variations of photosynthetic pigment content were assessed in the populations growing in different habitat types. The numbers of polymorphic bands were 18 and 6 for SCoT and ISSR, respectively. The percentage of polymorphism showed wide range amounted to 40.9 for SCoT and 25 for ISSR, while the number of amplicon bands ranged from 8-10 in SCoT and 2-9 in ISSR. The genetic relationships among populations using SCoT and ISSR analysis showed close relationship between the nearby but different habitat type populations such as sand mound and littoral populations, or between populations of same habitat types in the study region. The photosynthetic pigment content of chlorophyll a and b, and carotenoids in the littoral and intertidal populations were higher than that in the sand mound and salt plain populations. Populations inhabiting Nabq protected area have wide range of polymorphism among different habitat types. Further studies are required to investigate the genetic relationships among populations of A. marina inhabiting the eastern and western sides of the Red Sea. [ABSTRACT FROM AUTHOR]

Hard corals are precious marine creatures that comprise a complex form of symbiosis between symbiont algae and coral holobiont. For decades, corals have been challenged by disastrous events of climatic and anthropogenic etiologies. Such complex interactions have resulted in devastating disease episodes among coral populations worldwide. There is a scarcity of information about diseases of hard corals in the Gulf of Aqaba, Red Sea, Egypt. Therefore, the current study aims to investigate various diseases of hard corals in this pristine habitat within the Red Sea. Whitening and dark green dots were the most noticeable morphopathology among hard coral samples collected from Gulf of Aqaba. Some human-based pathogens, such as Rothia kristinae, Cupriavidus pauculus, and Delftia acidovorans, were isolated from some of the examined coral tissues, while the Burkholderia cepacia group was isolated from the nearby sediment. The final identities of the above-mentioned bacterial isolates have been molecularly confirmed using 16S RNA sequence analysis. Pathologically, diseased corals have been observed with changes such as some forms of tissue losses, degenerative changes, and eosinophilic granular amoebocytes/agranular cells infiltration. The frequent detection of some microbial pathogens of human origin could suggest deleterious forms of environmental pollution of anthropogenic origin. Ultimately, the entire existence of hard coral populations is mostly threatened by swiftly erupting climatic changes as well as environmental aquatic pollution. Thus, the current study concludes the real need for extensive ecological, biological, pathological, and immunological studies to determine the eminent threats and propose possible control means for better/sustainable hard coral populations. [ABSTRACT FROM AUTHOR]

Close to its southern end where it connects to the Red Sea rift, the Dead Sea strike‐slip fault (DSF) becomes trans‐tensional in the Gulf of Aqaba. Details of this transition, however, remain difficult to unravel as most of the active tectonic structures are located off‐shore. This study focuses on uplifted marine terraces located in the Gulf of Aqaba and on Tiran Island. Using high‐resolution tri‐stereo Pleiades satellite imagery, we build a Digital Surface Model (DSM) at a 0.5‐m resolution of the eastern coast of the gulf and Tiran Island to map 19 levels of marine terraces. The terraces are preserved at elevations from 1 m to almost 500 m above the current sea level. Correlating laterally U‐Th ages obtained along the gulf with the lower levels found on Tiran Island, we build an age model to estimate the ages of the upper terraces on the island. Combining this with the terrace heights from our DSM, we derive the uplift rate affecting the terraces. The geographic extent of the terraces along the gulf suggests that the DSF is responsible for uplift along the entire eastern coastline of the gulf at a rate of about 0.14 ± 0.03 mm/year at least over the Quaternary. The uplift rate of Tiran Island, located closer to the Red Sea rift, is faster at 0.21 ± 0.02 mm/year over the past 2.4 Myr. This faster uplift rate suggests a combined tectonic uplift related to both the Dead Sea strike‐slip fault system and the Red Sea rift. Key Points: Extension along the Dead Sea strike‐slip FaultUplift determination from fossil coral terracesInterplay between Dead Sea strike‐slip and Red Sea spreading center [ABSTRACT FROM AUTHOR]

The available data on occurrence patterns of cetaceans in the Red Sea area of the Kingdom of Saudi Arabia is very limited. The dearth of information is of pressing conservation concern as the coastline is undergoing rapid development as part of the Kingdom's effort to diversify its national economy. To understand how these developments will impact cetaceans in the region, the first large‐scale acoustic and visual survey in the Kingdom's part of the Gulf of Aqaba and the northeastern Red Sea was undertaken in 2020. The results of the acoustic surveys reveal 3.6 encounters per 100 km of track line of odontocete species with variable distribution across the study area. No baleen whale vocalizations were detected. Through visual surveys, five odontocete species were identified within the study area: Tursiops truncatus, T. aduncus, Stenella attenuata, S. longirostris, and two opportunistic sightings of a single Grampus griseus. [ABSTRACT FROM AUTHOR]

The results of this study showed that out of 287 individuals (135 males and 152 females) of the spider crab Menaethius monoceros collected from the Red Sea and the Gulfs of Suez and Aqaba, 15 individuals (6 males and 9 females) were infected with Parasacculina pilosella (Van Kampen & Boschma, 1925) (Polyascidae: Rhizocephala: Cirripedia: Crustacea). A total of 20 externae were recorded, including 11 singles, three doubles, and only one triple on the infected crab abdomens. The overall infection rate was 5.23% for the combined sexes at all sites, declined to 4.44% in males, but increased to 5.92% in females, reaching a higher rate of 16.07% in the populations of Marsa Alam and Shalateen sectors during summer. The examined externae have variable colors, sizes, and shapes based on their sexual maturity, which has been classified into four stages: immature or virgin, early mature, maturing, and late (spent externae). The largest number of externae was eight extruded on the 3rd abdominal segment, while it decreased to six, two, and one on the 4th, 2nd and 5th segments, respectively. The size of externae varied from 1.3 × 1.0 × 1.0 to 6.3 × 4.5 × 2.5 mm (Breadth × Height × Thickness). These results showed changes in the external secondary sexual characters of the infected males, represented by the remarkable broadness of the abdomen fringed with marginal setae and invagination of the sternum, but were limited in infected females.

Marine ecosystems play a vital role in supporting human well-being and coastal communities, offering essential ecosystem services (ES). This study focuses on the Gulf of Aqaba in Jordan, aiming to assess and map marine ecosystem services by leveraging stakeholder perceptions. To achieve this objective, a comprehensive survey was conducted with 64 participants representing diverse demographics. The survey, coupled with Participatory Geographic Information System (PGIS) exercises, gathered data on the awareness and valuation of ecosystem services. The integration of PGIS, a participatory mapping methodology, facilitated stakeholder involvement in spatial mapping exercises. This approach not only captured local knowledge but also enhanced the mapping process, providing a more nuanced and comprehensive understanding of stakeholder perspectives on marine ecosystem services in the Gulf of Aqaba. The results contribute to evidence-based decision-making, sustainable resource management, and the implementation of international agreements and policies for marine conservation and development in this ecologically important region. [ABSTRACT FROM AUTHOR]

The Gulf of Aqaba exhibits a nearly closed marine ecosystem, characterized by oligotrophic conditions, which give it the potential for phytoplankton to flourish. Coccolithophore samples were taken from two different sediment cores that were collected from the northern Gulf of Aqaba during the OceanX expedition. This study aims to construct the sea surface temperature over the past few hundred years by counting fossil coccolithophore communities in the northern Gulf of Aqaba through time. The forty-eight smear slides were prepared for coccolithophore identification and paleo-ecological investigation, and then studied under a polarized microscope with 1500x magnification. Taxonomic identification of coccolithophores is based on the outer scale found in the slides. A total of 300 specimens were counted in each slide. To assess the temperature, diversity and the relationship between species abundances, statistical indices were applied on the counted specimens. Coccolithophore assemblages are extremely abundant in well-preserved conditions, allowing for clear identification and an exact assessment of climatic change based on paleo-ecological studies. The Gephyrocapsa group, Emiliana group, Helicosphaera spp, Reticulofenestra spp, Coccolithus spp, Pontosphaera spp, Braarudosphaera spp and Umbilicosphaera spp were found in high numbers throughout all the cores. The Emiliana Group was the most abundant genus throughout all the cores, indicating long-term warming. Throughout core 3, the results showed a strong relation between Gephyrocapsa spp and the other coccolithophores, such as Coccolithus spp, Helicosphaera spp, and Braarudosphaera spp, as all of these species prefer cold water. The fluctuations in the numbers of the cold-preference (Gephyrocapsa) group versus warm-preference coccolithophores (Emiliana Group) led to tracking periodic changes in climate. The significant increase in numbers of Gephyrocapsa oceanica, Gephyrocapsa muellerae, Gephyrocapsa ericsonii, and Calcidiscus leptoporus in some samples, relative to the Emiliana Group, reveals that a cold environmental period dominated the Gulf during the Holocene. [ABSTRACT FROM AUTHOR]

The community structure of the fish family Scorpaenidae was investigated at nine sites along the Jordanian coast, examining various sites, depths, and habitats. The study employed a visual census technique with SCUBA diving for data collection. To present the findings, GIS maps were generated using ArcMap 10.8.1, showcasing the projected benthic cover, frequency of appearance, and relative abundance of the species. The community indices were computed using PRIMER-5 software (Primer-E 2000). The survey recorded a total of 417 scorpionfish individuals, representing seven different species, across 87 belt transects located at nine coastal sites. The average number of scorpionfish individuals per transect was approximately 4.8. Notably, three out of the seven species accounted for a significant 79.8% of all observed individuals. These dominant species were Pterois miles, which exhibited the highest relative abundance at 37.9%, followed by Synanceia verrucosa at 21.3%, and Pterois radiata at 5.4%. Further analysis of the data revealed that P. miles was most prevalent in both coral reef habitats (RA=55.6%) and sandy habitats (RA=47.0%). On the other hand, S. verrucosa showed the highest abundance in the seagrass habitat with a relative abundance of 53.4%. Additionally, P. miles was the most abundant fish species at a depth of 9 m, accounting for 46.9% of the population, while both S. verrucosa and Scorpaenopsis diabolus shared the highest relative abundance at reef flats with 44.4% each. Moreover, P. miles was the most commonly observed species across all sites, with a frequency of appearance (FA) of 70.1%. In the seagrass habitat, S. verrucosa dominated, with an FA of 88.9%. Furthermore, P. miles was frequently encountered at the sandy bottom and coral reef habitats, with FAs of 82.5% and 58.3% respectively. Reef flats showed an equal prevalence of both S. verrucosa and P. miles, each accounting for 50.0% of the observed scorpionfish. Cluster analysis revealed the presence of two main groups: the northern natural sites GH, HA, and PLB formed the first group, while the remaining sites constituted the second group. The species richness was found to be highest at a depth of 6 m, whereas the lowest richness was observed at reef flats. The sandy habitat exhibited the highest diversity index, while the coral reef habitats displayed the lowest diversity. This comprehensive survey provides valuable insights for decision-makers and managers, aiding them in making informed decisions to ensure the safety of beach users and visitors to Aqaba. Additionally, it contributes to public awareness regarding the potential risks posed by these fishes, thereby reducing the likelihood of injuries caused by encounters with them. [ABSTRACT FROM AUTHOR]

Algae are photosynthetic organisms which can be cultivated and produced in photo-bioreactors; therefore, choosing the design parameters and conditions are critical in order to achieve high efficiency and maximum productivity. Algae are of interest to biochemical industries because of their diverse species. This project seeks to build a photo-bioreactor tank to maximize Ulva lactuca non-seasonal survival to produce biodiesel from its biomass. The chosen design was because of the ease of monitoring, and the tank design effectively kept Ulva lactuca alive and fresh. Biodiesel was accomplished using an alkaline esterification for 50 g of dry mass of Ulva lactuca giving a relatively limited yield of approximate 13% of Ulva lactuca oil (4 ml) that was converted to (0.5 ml) biodiesel, compared with other oils such as soybean (42%), corn oil (60%) and cooked corn oil (40%). The yield of Ulva lactuca oil was statistically significantly lower than the other three types of oil (p-value = 0.0032). However, this project still aids in the economics of Jordan, as Ulva lactuca is grown locally in the Gulf of Aqaba. Ulva lactuca investment is worth considering because of its natural exposure, high yield, low cost, reduced algae contamination risk, and space requirements. [ABSTRACT FROM AUTHOR]

Incidents of parasitic infections of coastal (0-40m deep) fish species were investigated to assess ecosystem health and stability along Jordan's Gulf of Aqaba (GoA). The aim was to compare sites of probable anthropogenic impacts using the extent of infections and species richness indices. A total of 828 fish belonging to 60 species were collected and examined from 7 sites. Fish were brought to laboratory and examined for skin and gill lesions and/or parasites. Fish necropsy was undertaken to assess organ-specific parasitic infections. The infection prevalence (IV) of 8 disease agents pooled from all sites was Psuedodactylogyrus sp., Dactylogyrus sp., Copepod (Gnathia sp.), Ergasilus sp., Maxillopoda, Nematodes (Anisakis sp), Isopods and Platy helminthes. The highest IV was reported in fish gills by Flukes (helminthes), and Isopods and monogeneans were recorded in 88% of the examined fish. However, the highest % of infection was the copepods, Ergasilus sp. and Psuedodactylogyrus sp., while the lowest % was the helminthes (fish flukes). The gut parasites pseudodactylogyrus sp. and dactelogyrus sp. prevailed highest in fish collected at northern sits of GoA. These together with one nematode dominated sites of increasing urban activities. By comparing species richness indices of heteroxenous vs. monoxenous parasites in some fish, results suggest increased incidents of monoxenous parasite in fish collected at areas likely impacted by human activities along the coast. [ABSTRACT FROM AUTHOR]

The results of this study showed that out of 287 individuals (135 males and 152 females) of the spider crab Menaethius monoceros collected from the Red Sea and the Gulfs of Suez and Aqaba, 15 individuals (6 males and 9 females) were infected with Parasacculina pilosella (Van Kampen & Boschma, 1925) (Polyascidae: Rhizocephala: Cirripedia: Crustacea). A total of 20 externae were recorded, including 11 singles, three doubles, and only one triple on the infected crab abdomens. The overall infection rate was 5.23% for the combined sexes at all sites, declined to 4.44% in males, but increased to 5.92% in females, reaching a higher rate of 16.07% in the populations of Marsa Alam and Shalateen sectors during summer. The examined externae have variable colors, sizes, and shapes based on their sexual maturity, which has been classified into four stages: immature or virgin, early mature, maturing, and late (spent externae). The largest number of externae was eight extruded on the 3rd abdominal segment, while it decreased to six, two, and one on the 4th, 2nd and 5th segments, respectively. The size of externae varied from 1.3 × 1.0 × 1.0 to 6.3 × 4.5 × 2.5 mm (Breadth × Height × Thickness). These results showed changes in the external secondary sexual characters of the infected males, represented by the remarkable broadness of the abdomen fringed with marginal setae and invagination of the sternum, but were limited in infected females. [ABSTRACT FROM AUTHOR]

Tourism pressure on the Red Sea ecosystem have posed significant threats to numerous endemic species, including the Ghost Crab Ocypode saratan, which is exclusively found along a small stretch of beach in the Eilat/Aqaba Red Sea Gulf. Due to the limited understanding of their ecology, we investigated how tourism impacts the behavior of this species. Employing a natural setup, we compared burrow dimensions, pyramid structures, and density across three distinct beach sections subjected to varying levels of human interference. Access to a secluded beach, referred to as "No Man's Land," provided a crucial control for our study. This facilitated a comparative analysis of ghost crab activity among beaches experiencing differing levels of human disturbances: (1) a tourist beach characterized by continual high disturbance, (2) a naval beach subject to moderate and sporadic disturbances, and (3) the isolated "no man's land" beach devoid of human presence. Our observations revealed notable differences in ghost crab density among the three beaches. Furthermore, we observed that on the secluded beach, larger individuals tended to establish burrows farther from the waterline and construct taller sand pyramids. Given the significance of sexual selection processes, their conservation becomes imperative for the survival and potential expansion of the ghost crab population across the Gulf of Eilat/Aqaba. We propose a straight-forward and cost-effective strategy: the designation of short, secluded beach enclaves along this gulf. We believe that this approach will mitigate adverse impacts of tourisms while simultaneously benefiting various sandy beach species. [ABSTRACT FROM AUTHOR]

Accumulating data on the increasing degradation of coral reefs worldwide has led to a focus on the unique mesophotic coral ecosystem (MCE) as a potential refuge for threatened shallow-water species (i.e., the deep reef refugia hypothesis: DRRH). Sponges play a crucial role in coral-reef functioning but are often overlooked in benthic surveys. This knowledge gap is especially true for the Red Sea, where data on sponge abundance, coverage and species composition are scarce. Furthermore, to date, no study has examined mesophotic sponges in the Red Sea. Here we compared sponge abundance and diversity metrics between shallow and mesophotic reefs at two sites in the Gulf of Aqaba, northern Red Sea. We also examined the role of biotic and abiotic parameters in determining sponge variability between sites and depths. Sponge diversity metrics significantly varied with increasing depth and between sites. Sponge species composition also differed significantly between depth and sites. However, parameters measured in the water column, that is, Total Organic Carbon (TOC), Particulate Organic Carbon (POC), NOx, etc., did not differ between depths and sites, except for Synechococcus and Prochlorococcus concentration, which did. The findings indicated that site characteristics and biotic interactions may play an essential role in determining sponge diversity and community composition. Between-site differences in sponge fauna revealed in the study highlight the importance of considering the variability in the benthic communities and the factors controlling it when designing management tools for coral reefs, particularly for the northern Red Sea. [ABSTRACT FROM AUTHOR]

Accurately quantifying air–sea heat and gas exchange is crucial for comprehending thermoregulation processes and modeling ocean dynamics; these models incorporate bulk formulae for air–sea exchange derived in unstable atmospheric conditions. Therefore, their applicability in stable atmospheric conditions, such as desert-enclosed basins in the Gulf of Eilat/Aqaba (coral refugium), Red Sea, and Persian Gulf, is unclear. We present 2-year eddy covariance results from the Gulf of Eilat, a natural laboratory for studying air–sea interactions in stable atmospheric conditions, which are directly related to ocean dynamics. The measured mean evaporation, 3.22 myr-1 , approximately double that previously estimated by bulk formulae, exceeds the heat flux provided by radiation. Notably, in arid environments, the wind speed seasonal trend drives maximum evaporation in summer, with a minimum winter rate. The higher evaporation rate appears when elevated wind, particularly in the afternoon, coincides with an increase in vapor pressure difference. The inability of the bulk formulae approach to capture the seasonal (opposite from our measurements) and annual trend of evaporation is linked to errors in quantifying the atmospheric boundary layer stability parameter. Most of the year, there is a net cooling effect of surface water (- 79 Wm-2), primarily through evaporation. The substantial heat deficit is compensated by the advection of heat via northbound currents from the Red Sea, which we indirectly quantify from energy balance considerations. Cold and dry synoptic-scale winds induce extreme heat loss through air–sea fluxes and are correlated with the destabilization of the water column during winter and initiation of vertical water-column mixing. [ABSTRACT FROM AUTHOR]

Estimates of primary productivity have traditionally disregarded dark inorganic carbon fixation by marine microorganisms. Currently, only limited data are available from different systems on this potentially ecologically important process. We present monthly dark inorganic carbon fixation and photosynthetic rates from the euphotic layer of the northern Gulf of Aqaba collected over a decade between 2010 and 2020. Averaged dark inorganic carbon fixation rates from surface to 100 m depth, ranged from 99 to 173 mg C m−2 d−1, which corresponds to ~ 43% of the annual primary productivity at this location. The lowest dark inorganic carbon fixation rates were found during winter, contributing ~ 7.5% of the integrated primary productivity. During the oligotrophic summer, dark inorganic carbon fixation comprised a larger fraction of the integrated primary productivity estimated as ~ 12%. In accordance, dark inorganic carbon fixation contributed ~ 6% to the particulate organic carbon flux during the winter and ~ 30% during summertime. Complimentary nutrient‐enrichment bioassays of seawater from 5 m show that dissolved organic nutrient enrichment (P and C based) significantly elevates dark inorganic carbon fixation, whereas addition of dissolved inorganic nutrients (PO43+, NO3−, or both) significantly increased photosynthesis but to a lesser extent dark inorganic carbon fixation. These results suggest that dark inorganic carbon fixation may be an important biochemical process throughout the euphotic zone of oligotrophic seas, and thus should be incorporated into oceanic carbon production estimates. [ABSTRACT FROM AUTHOR]

The kawakawa Euthynnus affinis, is a highly commercial tuna species in the Red Sea. To assess the species’ fishery status, the life history and population dynamic parameters have to be identified. A total of 615 length measurement data were randomly collected during the period from February 2021 to May 2023 from the Gulf of Aqaba, Red Sea, Egypt. Life history characteristics comprising age and growth, mortality, and utilization rate were evaluated based on the length frequency analysis. The average total length was 55.32±6.53 cm for males and 54.95±6.50 cm for females. The "b" values in length-weight relationship were estimated at 2.981 and 2.962 for males and females respectively which designated that E. affinis grows isometrically. The combined sexes’ growth parameters were computed for as L∞= 83.64 cm, K= 0.47 year -1 and t0= -0.22 year. Total mortality, natural mortality and fishing mortality were valued at 1.413, 0.77 and 0.643 year -1 respectively, with an exploitation rate of 0.455. The biological reference points Fopt and Flimit were calculated at 0.39 and 0.51 year -1 respectively. The results revealed a good situation for E. affinis stock in the Gulf of Aqaba, since the majority of captured kawakawa had achieved its maturation as indicated by Lc > Lm. The results demonstrating that E. affinis fishery in the Gulf of Aqaba, Egypt has a potential for development nevertheless any recommendations should be consider the tuna species’ migratory behavior and the multi-species nature of Gulf of Aqaba fisheries in Egypt. Furthermore, for the species’ sustainable management, there is a need for continuous monitoring of fishing effort and improve fishery data gathering. [ABSTRACT FROM AUTHOR]

Coral reefs are among the most diverse ecosystems on our planet, and essential to the livelihood of hundreds of millions of people who depend on them for food security, income from tourism and coastal protection. Unfortunately, most coral reefs are existentially threatened by global climate change and local anthropogenic pressures. To better understand the dynamics underlying deterioration of reefs, monitoring at high spatial and temporal resolution is key. However, conventional monitoring methods for quantifying coral cover and species abundance are limited in scale due to the extensive manual labor required. Although computer vision tools have been employed to aid in this process, in particular structure‐from‐motion (SfM) photogrammetry for 3D mapping and deep neural networks for image segmentation, analysis of the data products creates a bottleneck, effectively limiting their scalability.This paper presents a new paradigm for mapping underwater environments from ego‐motion video, unifying 3D mapping systems that use machine learning to adapt to challenging conditions under water, combined with a modern approach for semantic segmentation of images.The method is exemplified on coral reefs in the northern Gulf of Aqaba, Red Sea, demonstrating high‐precision 3D semantic mapping at unprecedented scale with significantly reduced required labor costs: given a trained model, a 100 m video transect acquired within 5 min of diving with a cheap consumer‐grade camera can be fully automatically transformed into a semantic point cloud within 5 min. We demonstrate the spatial accuracy of our method and the semantic segmentation performance (of at least 80% total accuracy), and publish a large dataset of ego‐motion videos from the northern Gulf of Aqaba, along with a dataset of video frames annotated for dense semantic segmentation of benthic classes.Our approach significantly scales up coral reef monitoring by taking a leap towards fully automatic analysis of video transects. The method advances coral reef transects by reducing the labor, equipment, logistics, and computing cost. This can help to inform conservation policies more efficiently. The underlying computational method of learning‐based Structure‐from‐Motion has broad implications for fast low‐cost mapping of underwater environments other than coral reefs. [ABSTRACT FROM AUTHOR]

Carbonate and silicate natural sediments from the gulf of Aqaba-Jordan have been used to study adsorption of nickel(II), lead(II) and cadmium(II) ions, separately, from aqueous solutions. Both sediment types were characterised by FTIR, XRD and SEM. Adsorption of these metal ions were investigated using batch technique as a function of initial concentration of metal cations, adsorbent dosage, initial pH, contact time and temperature. The metal uptake enhanced with increasing pH until a maximum removal at pH 8.0 for Ni, 5.0 for Pb and 6.0 for Cd. Kinetic study shows that the adsorption obeys a pseudo-second-order kinetic model. The adsorption isothermal behaviour of the metal ions uptake onto carbonate and silicate sediments were examined using Langmuir, Freundlich and Dubinin–Radushkevich (D-R) adsorption isotherms. The maximum adsorption capacity obtained by Langmuir isotherm model (25°C) onto carbonate sediments was 2.64, 4.41 and 4.15 mg/g for Ni(II), Pb(II) and Cd(II), respectively. While the adsorption onto silicate sediments was 2.57, 3.56 and 3.15 mg/g, respectively. These adsorption values on carbonate sediments comparing to silicate sediments were attributed to some physical and chemical properties of both sediments, especially the higher permeability and porosity for carbonate sediments. Thermodynamic functions, ΔG*, ΔH* and ΔS* were determined. Negative ΔG* values show that the adsorption process of these metal ions onto both sediments is spontaneous. While the positive ΔH* values indicate that adsorptions are endothermic, and the positive values of entropy ΔS* suggest that the adsorption is driven by increasing of randomness. Conservative calculations using the data in this study and some other from the literature shows that the shallow sediments would adsorb roughly 7 × 10 16 kg of heavy metals that may be introduced into the sea through different anthropogenic activities. [ABSTRACT FROM AUTHOR]

Black corals occur as part of benthic assemblages from shallow to deep waters in all oceans. Despite the importance in many benthic ecosystems, where these act as biodiversity aggregators, antipatharians remain poorly studied, with 75% of the known species occurring below recreational SCUBA diving depth limits. Currently, information regarding the diversity and evolutionary history is limited, with most studies focusing on Hawaii and the South Pacific Ocean. Other regions of the world have received less attention, such as the Red Sea, where only two black coral families and four genera have been recorded. We provide the first analysis of the molecular diversity of black corals in the eastern Gulf of Aqaba and the northern and central Saudi Arabian Red Sea, based on a dataset of 161 antipatharian colonies collected down to 627 m deep. Based on specimen morphology, we ascribed our material to 11 genera belonging to 4 of the 7 known Antipatharia families, i.e. Antipathidae, Aphanipathidae, Myriopathidae and Schizopathidae. The genus level phylogeny of three intergenic mitochondrial regions, the trnW-IGR-nad2 (IgrW), nad5-IGR-nad1 (IgrN) and cox3-IGR-cox1 was reconstructed including previously published material. Overall, we recovered six molecular clades that included exclusively Red Sea sequences, with the highest diversity occurring at mesophotic depths. This study highlights that diversity of black corals in the Red Sea is much higher than previously known, with seven new generic records, suggesting that this basin may be a hotspot for antipatharian diversity as is known for other taxa. Our results recovered unresolved relationships within the order at the familial and generic levels. This emphasises the urgent need for an integration of genomic-wide data with a re-examination of informative morphological features necessary to revise the systematics of the order at all taxonomic levels. [ABSTRACT FROM AUTHOR]

The seismogenic characteristics of the Gulf of Aqaba zone have been assessed using the maximum likelihood method to estimate various earthquake recurrence parameters. These parameters encompass the β-value, annual recurrence rate (λ), and maximum probable magnitude (Mmax). This assessment has identified three sub-seismogenic zones, each corresponding to specific structural faults within the Gulf. These zones are associated with the Aragonese, Arnona and Aqaba faults, delineating pull-apart basin structures in the Gulf of Aqaba. An updated earthquake catalogue has been compiled using a unified moment magnitude (Mw) scale to improve the analysis, established by developing two empirical relationships. According to the findings of this study, there is a possibility that the Aragonese seismogenic zone could experience an earthquake with a maximum magnitude of 7.7, highlighting a significant seismic hazard in the region. While acknowledging the inherent uncertainties in this assessment, a probabilistic seismic hazard was calculated for hard rock conditions within a spatial area divided into elementary cells, each measuring 0.1°×0.1°. The highest peak ground acceleration (PGA) is associated with a spectral frequency of 5.0 to 10.0 Hz and could significantly impact building codes in the region. The spatial distribution variations of seismic hazard corresponding to the proposed sub-seismogenic zones indicate a high degree of crustal heterogeneity and seismotectonic complexity. This comprehensive assessment contributes to understanding seismic hazards that may import from the Gulf of Aqaba seismogenic zone.

The seasonal and spatial evolution of the mixed layer (ML) in the Red Sea (RS) and the influence of atmospheric buoyancy and momentum forcing are analyzed for the 2001–2015 period using a high-resolution (1/100°, 50 vertical layers) ocean circulation model. The simulation reveals a strong spatiotemporal variability reflecting the complex patterns associated with the air–sea buoyancy flux and wind forcing, as well as the significant impact of the basin’s general and mesoscale circulation. During the spring and summer months, buoyancy forcing intensifies stratification, resulting in a generally shallow ML throughout the basin. Nevertheless, the results reveal local maxima associated with the influence of mesoscale circulation and regular wind induced mixing. Under the influence of surface buoyancy loss, the process of deepening of the ML commences in early September, reaching its maximum depth in January and February. The northern Gulf of Aqaba and the western parts of the northern RS, exhibit the deepest ML, with a gradual shoaling toward the south, primarily due to the surface advection of relatively fresh water that enters the basin from the Gulf of Aden. The mixed layer depth (MLD) variability is primarily driven by atmospheric buoyancy forcing, especially its heat flux component. Although evaporative fluxes dominate the annually averaged surface buoyancy forcing, they exhibit weak seasonal and spatial variability. Wind induced mixing exerts a significant impact on the MLD only locally, especially during summer. Of particular importance are strong winds channeled by topography, such as those in the vicinity of the Strait of Bab-Al-Mandeb and the straits connecting the two gulfs in the north, as well as lateral jets venting through mountain gaps, such as the Tokar Jet in the central RS. The analysis highlights the complex patterns of air-sea interactions, thermohaline circulation, and mesoscale activity, all of them strongly imprinted on the MLD distribution. [ABSTRACT FROM AUTHOR]

Mangrove forests support a wide diversity of habitats for numerous macrofauna species that are crucial to the health of mangrove ecosystems, as well as a vast variety of macroinvertebrate species. Therefore, it is necessary to periodically update our knowledge of the diversity of macrofaunal communities found throughout the mangrove forests of the Aqaba Gulf. This study seeks to examine biodiversity and identify macroinvertebrate fauna in various mangrove-associated habitats, i.e., genuine mangrove forests and neighboring coastal mangrove zones with varying levels of ecological heterogeneity. The belt transects and quadrate approach were used to collect samples from five distinct locations along the Aqaba Gulf mangrove. Overall, 8186 organisms belong to 118 species. Eighty-four molluscan species, 23 crustacean species, and 11 echinoderm species were recorded throughout the present investigation. The diversity of species was estimated for each site. Rowaisseia station showed significantly greater numbers for taxonomic richness, and the lowest number was present in Gharqana station. The statistical assessment of the various environmental factors and sediment characteristics in terms of abundance and variety of species of macroinvertebrate fauna revealed that the composition of bed sediment has a strong influence on the distribution and variation of macrofaunal communities. The current study's findings will aid in the conservation of mangrove forests by providing a better understanding of the ecological patterns and functions of benthic macrofaunal communities, which will be useful in future studies for habitat management and monitoring programs in the Gulf of Aqaba mangrove forests. [ABSTRACT FROM AUTHOR]

Annelid biodiversity studies in the Red Sea are limited and integrative taxonomy is needed to accurately improve reference libraries in the region. As part of the bioblitz effort in Saudi Arabia to assess the invertebrate biodiversity in the northern Red Sea and Gulf of Aqaba, Perinereis specimens from intertidal marine and lagoon-like rocky environments were selected for an independent assessment, given the known taxonomic ambiguities in this genus. This study used an integrative approach, combining molecular with morphological and geographic data. Our results demonstrate that specimens found mainly in the Gulf of Aqaba are not only morphologically different from other five similar Perinereis Group I species reported in the region, but phylogenetic analysis using available COI sequences from GenBank revealed different molecular operational taxonomic units, suggesting an undescribed species, P. kaustiana sp. nov. The new species is genetically close and shares a similar paragnath pattern to the Indo-Pacific distributed P. helleri, in particular in Area III and Areas VII–VIII. Therefore, we suggest it may belong to the same species complex. However, P. kaustiana sp. nov. differs from the latter mainly in the shorter length of the postero-dorsal tentacular cirri, median parapodia with much longer dorsal cirri, posteriormost parapodia with much wider and greatly expanded dorsal ligules. Additionally, two new records are reported for the Saudi Neom area belonging to P. damietta and P. suezensis, previously described only for the Egyptian coast (Suez Canal) and are distributed sympatrically with the new species, but apparently not sympatric with each other. [ABSTRACT FROM AUTHOR]

Semi‐enclosed seas are often associated with elevated local threats and distinct biogeographic patterns among marine fishes, but our understanding of how fish assemblage dynamics vary in relation to relatively small semi‐enclosed seas (e.g., the Gulf of Aqaba) remains limited. Baited remote underwater video surveys (n = 111) were conducted across ~300 km of coral reef habitats in the Gulf of Aqaba and the northern Red Sea. A total of 55 predatory fish species were detected, with less than half of all species (n = 23) observed in both basins. Relative abundance patterns between the Gulf of Aqaba and the northern Red Sea were variable among taxa, but nearly twice as many predatory fish were observed per unit of effort in the northern Red Sea. In general, assemblages in both basins were dominated by three taxa (Epinephelinae, Carangidae, and Lethrinidae). Large‐bodied and threatened species were recorded at very low abundances. Multivariate analysis revealed distinct assemblage structuring of coral reef predators between the Gulf of Aqaba and the northern Red Sea. Most of the species driving these differences were recorded in both basins, but occurred at varying levels of abundance. Environmental factors were largely unsuccessful in explaining variation in assemblage structuring. These findings indicate that biological assemblages in the Gulf of Aqaba are more distinct than previously reported and that reef fish assemblage structuring can occur even within a relatively small semi‐enclosed sea. Despite inter‐basin assemblage structuring, the overall low abundance of vulnerable fish species is suggestive of overexploitation in both the Gulf of Aqaba and the northern Red Sea of Saudi Arabia. As the region surveyed is currently undergoing large‐scale coastal development, the results presented herein aim to guide spatial management and recovery plans for these coral reef systems in relation to this development. [ABSTRACT FROM AUTHOR]

The successful management of coral reefs necessitates understanding the genetic characteristics of reefs' populations since levels of genetic diversity play a critical role in their resilience, enabling them to withstand environmental changes with greater efficacy. To assess the genetic diversity and connectivity of the widespread Indo-Pacific coral, Stylophora pistillata, eight microsatellite loci were employed on 380 tissue samples collected from eight sites along the northern Gulf of Eilat, Red Sea. We documented deviations from the Hardy–Weinberg equilibrium and observed low heterozygosity and high values of expected heterozygosity (0.59 and 0.82, respectively). The relatively high FST values and STRUCTURE analysis results showed population fragmentation along the short coastline (<12 km). These results signify isolation by distance, low gene flow between most populations, and possible non-random mating. These results are connected to this species' sexual reproduction traits, a brooding coral species with planulae that settle shortly upon release with limited connectivity that are most probably further exacerbated by anthropogenic impacts imposed on Eilat's reefs. This study provides insights into the connectivity and population genetics of S. pistillata residing in an urbanized northern Red Sea reef and reinforces the need for better management of the current MPA, employing future active coral reef restoration in the area. [ABSTRACT FROM AUTHOR]

Objective: The reef flats at the Gulf of Aqaba, Jordan, are exposed to the accelerated development associated with increased interest in recreational marine activities such as diving and snorkeling. The physical damage from net entanglement and overfishing has also affected the coral reef. This research evaluated the effects of aquatic, commercial, and land-based activities on the total coral cover in the Aqaba Marine Park (Now the Aqaba Marine Reserve) and the power station located north of the reserve. Materials and Methods: The line transect method was used to estimate the coral cover, followed by measuring the distance of the 13 diving sites to the different landscape disturbances and applying a linear regression analysis. Results: The results showed no significant relationship between the distance to the nearest human disturbance and the entire coral cover in the depth categories. In addition, there was no significant difference between low and high-frequency diving pressure and the mean coral cover at any depth category and no significant difference in the mean coral cover between low and high-frequency snorkeling sites. Sites with higher fishing activity had significantly lower coral cover than sites with lower fishing activity. However, there was no significant difference in the mean coral cover between sights with higher and lower fishing activity at the 21-30 m depth range. Conclusion: The study illustrated that local marine recreational activities (diving and snorkeling) do not affect the coral cover structure up to 10 meters depths. However, considerable coral degradation was found in high fishing zones less than 10 meters deep, which correlates with illegal fishing activities. We believe illegal fishing has negatively affected the coral cover, and recreational marine activities reduced coral cover, especially in diving areas requiring shore entrance. [ABSTRACT FROM AUTHOR]

Storms are among the most common disturbances within coral reef ecosystems. However, their effects on the diversity of reef fishes vary and range from negative to positive. Moreover, storm impacts on spatial heterogeneity of the community are unclear, as an uneven spatial impact can increase heterogeneity, whereas uniform habitat degradation can decrease heterogeneity. Understanding how storms alter the community spatial structure is crucial for evaluating the resilience of reef fish communities across scales. We explored the effect of a strong storm that occurred in March 2020 in the Gulf of Aqaba, where storms are rare. Using data collected from reef knolls surveyed repeatedly since 2015, we analyzed the storm's effects on the structure and spatial heterogeneity of the fish community across multiple scales. We found a post-storm decrease in fish density which dropped to less than half the pre-storm state, along with an increase in community evenness. Yet, the storm impacts differed considerably between sites located less than 5 km apart. We further found that the spatial heterogeneity of the community increased after the storm. However, this was primarily driven by a local reduction in abundance rather than an uneven spatial loss of species. The fish community showed striking recovery and regained baseline richness, abundance, and diversity values within a year. Thus, it appears that although storms may cause short-term increases in spatial heterogeneity, these changes are caused by temporary local losses, and the storm did not produce long-lasting spatial effects on the reef fish community. Additionally, our results suggest the resilience of a reef fish community unaccustomed to storm disturbances. [ABSTRACT FROM AUTHOR]

Egyptian fisheries including the aquaculture represent an important sector in the national economy, and it is a source of employment. All studies dealing with the stock assessment and fisheries management in Egypt confirmed the overexploitation situation for most commercial stocks leading to a serious decrease in domestic fish production from natural resources. This situation made the fisheries managers in Egypt explore new fishing areas to enhance fish production in Egypt. The present work was undertaken as a part of NIOF scientific plan about the Gulf of Aqaba fisheries and how rationally it can be exploited. Fish biology and population dynamics are fundamental for fish stock assessment and its management. Some biological and dynamical parameters of Lethrinus variegatus from the Gulf of Aqaba, Egypt were investigated to assess its exploitation status. Comparisons of age and growth characteristics recorded no significant differences (P> 0.05) between the sexes. The von Bertalanffy growth parameters for pooled data were K= 0.51/year, L8= 25.79cm TL and t0= -0.387 year. The mean size at which the fish attained sexual maturity for L. variegatus was 16.33cm TL. The mean size at first capture was 17.31cm, which was greater than the size at first sexual maturity, indicating the healthy status of L. variegatus stock in the Gulf of Aqaba. The fishing mortality rate for L. variegatus (0.80/yr) was substantially greater than the target Fopt (0.51/yr) and limit Flimit (0.67/yr) estimates. The slender emperor stock was in its optimum situation as the current exploitation rate was 0.44/yr. The results of the study are important to fisheries management authorities in the region since they will contribute to planning the regional fishery management policies in Egypt. [ABSTRACT FROM AUTHOR]

Gulf of Eilat is rich with energy resources, however any industrial natural resource development requires additional safety, as local eco‐system has to be preserved. In contrast to bivariate reliability approaches, known to their accurate predictions of extreme response and load levels for two‐dimensional dynamic systems, this study suggests and validates novel structural reliability method, which is being appropriate method for high‐dimensional dynamic systems. Conventional reliability methods do not have an advantage of dealing easily with high‐dimensional nonlinear dynamic systems, especially with non‐linear cross‐correlations between different system components. Advocated approach does not have limitations on the system's number of degrees of freedom, and it can accurately assess dynamic system's failure risks. Main purpose of this study was to benchmark state‐of‐the‐art reliability methodology, while utilizing available dataset efficiently. Note that advocated approach is not limited to offshore engineering example, studied here, and it has wide range of potential engineering and design applications. [ABSTRACT FROM AUTHOR]

As impacts on the Mediterranean Sea are expected to grow in the future, especially with climate change, habitat degradation, and displacement of native species by non-indigenous species (NIS), the investigation of significant alterations to trophic levels in this diverse marine habitat is important. Analysis of stable isotopes from targeted consumers has previously been shown to reliably reflect that of primary producers, thus enabling us to describe and highlight potential shifts in the food web of a particular ecosystem. In this study, we used δ13C values of essential amino acids (AA) in order to examine the dietary composition of established non-native, Lessepsian fish migrants in the Eastern Mediterranean Sea compared to that of the same fish species from their original population in the Gulf of Aqaba, Red Sea. Our data show that a clear variance in carbon isotopic signatures exists in food sources consumed by the same species between the different environments, with the exception of the classic herbivore, Siganus rivulatus (Forsskål & Niebuhr, 1775), whose very similar isotopic patterns reflect the algal source they predominantly consume in both locations. With the results of this research, we propose that Lessepsian fishes with the ability to maintain their nutritional patterns, though not necessarily that of their original food source, will acclimatize better in their new habitat. Consequences of flourishing Lessepsian fish populations include a further tropicalization of the Eastern Mediterranean Sea and the likely restructuring of local food webs. [ABSTRACT FROM AUTHOR]

Ulva spp., one of the most important providers of marine ecosystem services, has gained substantial attention lately in both ecological and applicational aspects. It is known that macroalgae and their associated microbial community form an inseparable unit whose intimate relationship can affect the wellbeing of both. Different cultivation systems, such as integrated multi-trophic aquaculture (IMTA), are assumed to impact Ulva bacterial community significantly in terms of compositional guilds. However, in such a highly dynamic environment, it is crucial to determine how the community dynamics change over time. In the current study, we characterized the microbiota associated with Ulva fasciata grown as a biofilter in an IMTA system in the Gulf of Aqaba (Eilat, Israel) over a developmental period of 5 weeks. The Ulva-associated microbial community was identified using the 16S rRNA gene amplicon sequencing technique, and ecological indices were further analyzed. The Ulva-associated microbiome revealed a swift change in composition along the temporal succession, with clusters of distinct communities for each timepoint. Proteobacteria, Bacteroidetes, Planctomycetes, and Deinococcus-Thermus, the most abundant phyla that accounted for up to 95% of all the amplicon sequence variants (ASVs) found, appeared in all weeks. Further analyses highlighted microbial biomarkers representing each timepoint and their characteristics. Finally, the presence of highly abundant species in Ulva microbiota yet underestimated in previous research (such as phyla Deinococcus-Thermus, families Saprospiraceae, Thiohalorhabdaceae, and Pirellulaceae) suggests that more attention should be paid to the temporal succession of the assembly of microbes inhabiting macroalgae in aquaculture, in general, and IMTA, in particular. Characterizing bacterial communities associated with Ulva fasciata from an IMTA system provided a better understanding of their associated microbial dynamics and revealed this macroalgae’s adaptation to such a habitat. [ABSTRACT FROM AUTHOR]

Trace metals (TM) delivered by atmospheric dust play a key role in oceanic biogeochemical cycles. However, the impact of short‐term environmental perturbations such as dust storms and sediment resuspension events on the oceanic water column is poorly constrained due to the low temporal sampling resolution and episodic nature of these events. The Gulf of Aqaba (GoA), Red Sea, is a highly accessible deep oligotrophic water body featuring exceptionally high atmospheric deposition fluxes that provide the main source of TMs to the GoA surface water. Here, we present a 2‐year time series of dissolved manganese, cobalt, nickel, copper, zinc, cadmium, and phosphate concentration profiles sampled in the GoA. The study focuses on daily time scale dust storms and episodes of sediment resuspension to quantify the immediate impact of these events on dissolved TM cycling. Counter‐intuitively, upper mixed layer TM inventories decrease with increasing aerosol loads, with the effects of aerosol‐induced TM scavenging and dissolution peaking 5–6 days after aerosol deposition. Dust storms promote intense TM scavenging, with TM inventories decreasing by up to 44%, but seldom lead to TM enrichment. Similarly, sediment resuspension and flash flood events triggered significant TM scavenging. These findings highlight the potential dual role of atmospheric deposition in the oceans as a long‐term source of dissolved TMs and a short‐term sink. The in situ observations presented here may be used to understand and quantify the global impact of abrupt environmental events on oceanic chemical compositions. Plain Language Summary: Trace metals (TM) in the oceans are essential nutrients for marine life and serve as the base for various oceanic processes. The main source of these metals in the upper part of the ocean is dust that settles from the atmosphere. This dust is largely delivered during short‐term dust storms. However, little is known about their impact since sampling in open ocean environments is rarely conducted in association with such storms. This study focuses on the Gulf of Aqaba in the Red Sea, which is one of the dustiest regions on Earth. We measured TM in seawater on a daily basis before and after dust storms to record their effects on TM levels in seawater. The results show that surprisingly, increases in dust loads during dust storms are associated with lower levels of TM in seawater. This reflects a process of metal adsorption onto dust particles sinking in seawater. These unique findings allow us to quantify the impacts of dust on seawater trace metal contents, and demonstrate that on the long term, dust is a source of metals to the oceans, but on shorter time scales, dust is also capable of removing metals from seawater. Key Points: Dissolved trace metals were measured at a daily resolution in the Gulf of Aqaba, Red Sea, across dust storms and other perturbative eventsUpper water column trace metal inventories decrease with increasing dust loads. Aerosol‐induced shifts peak ∼5–6 days after dust depositionDust storms and sediment resuspension events drive a decrease in trace metal (Mn, Co, Ni, Cu, and Cd) concentrations due to particle scavenging [ABSTRACT FROM AUTHOR]

The objective of the Jordan Red Sea-Dead Sea (RSDS) project is to transport desalinated water from the Gulf of Aqaba to the Dead Sea. It aims to resolve two fundamental issues in Jordan: the lack of potable water in the country's center and the low water level in the Dead Sea. Desalinated seawater should be pumped from the Gulf of Aqaba to the Dead Sea as part of the RSDS project. This study is not only the first study to focus on the feasibility of using renewable energy sources to meet the project's energy needs, but the approach taken in this research is also novel. It employs a variety of software packages in order to accomplish the research goals. Thus, a number of operational scenarios for the RSDS project employing renewable energy technologies, as these resources are essential for sustainable development, are proposed. Based on the availability of renewable energy sources in the project region, only solar and wind technologies are included in the technology selection process. The selection of a suitable technology from renewable energy technologies was based on eight scenarios that were developed using several selection criteria. The social, technical, environmental, risk evaluation, and financial impact scenarios were investigated. Analytic hierarchy process and multi-criteria decision analysis were utilized to evaluate the electricity generation options for the project. The results indicated that the economic scenario is the optimal scenario for covering the entire load. Levelized Cost Of Energy (LCOE) and payback period are sub-criteria for this scenario. The primary goal of this scenario is to cover the load with the lowest LCOE and shortest payback period possible. The results indicated that a 945 MW Photovoltaic plant and a 630 MW wind energy plant are required to cover the total loads for desalination and water pumping. Energy storage is essential in any scenario where renewable energy sources are used to meet demand. Electric vehicles are employed in this research as a kind of energy storage to lessen the demand for more traditional storage methods. The number of 85 kWh electric vehicles needed to replace traditional storage medium is estimated. It is determined that 53,614 and 57,584 electric vehicles in the 24 hour and 12 hour operating times, respectively, are required under the economic scenario. [ABSTRACT FROM AUTHOR]

The present study was carried out to investigate the accumulation pattern, magnitude and distribution of the phosphate rock dust particles that reach the coastal seawater of the Jordanian Gulf of Aqaba during ship-loading at the Phosphate Loading Berth (PLB). The concentration of phosphate-phosphorus was measured in water, sediment and trap-sediments. The speed and direction of currents in the area of the PLB were also measured to assess its effect on the transportation, sedimentation and distributions of phosphate dust particles within the study area. The analysis and examination of the results indicate that phosphate pollution is located mainly near the phosphate loading berth. The results show that the concentrations of phosphorus (total phosphorus (TP), inorganic (IP), and organic (OP) in trap-sediments were higher than their concentrations in sediments and IP was the major species of phosphorus in the study area. The statistical analysis showed that TP, IP, OP in trap-sediments and sediments of PLB differ significantly from those of all other sites. The concentration of TP, IP and OP were higher in the power station north (PSN) and central power station (PS) located to the south of PLB compared to the concentrations at stations located to the north of PLB and thus reflecting the effect of prevailing southward current. The increase in dissolved inorganic phosphorus (DIP) concentration in the water of the PLB area is not high to cause significant increase in the DIP in the water of the Gulf of Aqaba to abnormal or hazardous levels. [ABSTRACT FROM AUTHOR]

Coral reefs are facing rapid deterioration, primarily due to a global rise in seawater temperature. In conjunction, the frequency and intensity of extreme high temperature events, known as marine heatwaves (MHWs), are increasing. The Gulf of Aqaba (GoA) in the northern Red Sea is home to corals known for their thermal resilience, yet concerns have been raised regarding the potential for MHWs to put this coral refuge at risk. In summer of 2021, the hottest MHW so far occurred in the GoA, with sea surface temperatures peaking at 31°C and persisting above the local summer maximum for 34 days. To assess the physiological response of the corals Stylophora pistillata and Pocillopora damicornis to this event, we analyzed the monthly content across a year of host and symbiont proteins, carbohydrates, and lipids, pre-, during, and post the MHW, as a proxy for metabolic stress. We found that the MHW was not fatal to either species and did not induce bleaching, based on algal densities and chlorophyll content. Species-specific responses were detected. In S. pistillata, host protein content decreased (33%) at the onset of the MHW (August) compared to pre-MHW levels (July). Algal symbionts of S. pistillata were unaffected by the MHW in their maximal photosynthetic efficiency (Fv/Fm) and exhibited higher carbohydrate levels (+34%) at the end of the MHW (September) compared to its onset. In contrast, no significant catabolic response was detected in P. damicornis host or symbionts, and the maximal relative electron transport rate (rETRmax) of symbionts was 37% higher during the MHW than the annual average. These results highlight the remarkable ability of common GoA corals to withstand extreme thermal anomalies, underscoring the global significance of this coral refuge.

The Gulf of Aqaba is known for its high seismic activity in Egypt and the Middle East. An inversion technique was applied to 113 earthquakes of magnitude 2.5 to 7.2 to distinct subsets of data based on tectonic regionalization to define the stress regime in the Gulf of Aqaba involving the Eilat basin, Aragonese basin, and Dakar basin. The stress inversion revealed two active stress patterns; an active strike-slip in the Eilat basin and a dominant extensional regime in the Dakar basin, whereas both strike-slip and extensional regimes coexist in the Aragonese basin. The stress pattern in the Eilat basin is consistent with the movement along the Dead Sea Transform Fault. In contrast, the extensional regime in the Dakar basin aligns with the extensional stress field throughout the northern Red Sea. The coexistence of two dominant types of stress regimes in the Aragonese basin is likely a result of the superposition of the two main neighbouring stress regimes: the strike-slip regime along the Gulf of Aqaba Dead Sea Transform Fault and the extensional stress state across the northern Red Sea. The orientations of the minimum principal stress in the three basins are almost similar, indicating ENE trending, nearly horizontal extension. [ABSTRACT FROM AUTHOR]

In March 2020, an unusually intense storm system struck the Gulf of Aqaba‐Eilat, resulting in severe shoreline damage. This brief account examines post‐storm observations of inconsistent damage patterns and structural changes along a specific coastal stretch located at the south beach of Eilat. Certain sections of the coastline experienced direct impact from extreme waves on the south‐southeast‐facing shallow reef, resulting in areas where rocks were completely stripped of corals due to sediment backwash. Conversely, areas characterized by ridges and deep troughs saw the loss of branching corals and some massive colonies, while many small corals survived. A neighboring area with a well‐developed fringing reef suffered lesser damage. Between the severely affected shallow reef and the robust fringing reef lies an unconsolidated slope that migrated eastward by at least 2 m following the storm, incorporating numerous coral colonies dislodged by the event. We propose that this slope advances with each major storm occurrence, influencing the characteristics of nearby shores and coral reefs. This case demonstrates how storm events, in conjunction with geomorphology, have a cumulative and significant impact not only on the structure of coral communities but also on the fundamental shape of coral reefs themselves. As climate change amplifies the range, intensity, and frequency of storms, comprehending these processes becomes increasingly crucial. [ABSTRACT FROM AUTHOR]

The Mg/Ca of marine calcareous Planktic Foraminifera (PF) shells is commonly used for sea surface temperature reconstructions. However, compared to open marine environments, hypersaline (>40) oligotrophic seas have been shown to accommodate PF with higher Mg/Ca and divergent temperature to Mg/Ca relationships. To investigate influencing factors of PF Mg uptake in hypersaline regions, we measured the Mg/Ca of two flux‐dominating PF species, Globigerinoides ruber albus and Turborotalita clarkei, derived from a monthly resolved time series of sediment traps in the Gulf of Aqaba, northern Red Sea as well as the corresponding temperature, salinity, and pH values. The PF exhibit elevated Mg/Ca which cannot be explained by post‐deposition or interstitial sediment diagenetic processes. G. ruber albus displays Mg/Ca trends that strongly follow seasonal mixed layer temperature changes. Conversely, T. clarkei Mg/Ca trends do not follow temperature but rather show significant Mg/Ca enrichment following mixing of the surface water column. We present a framework for incorporating elevated Mg/Ca into global Mg/Ca‐T calibrations for G. ruber albus and present a new Mg/Ca‐T calibration suitable for hypersaline marine environments. Plain Language Summary: Past seawater temperature is reconstructed from the magnesium‐to‐calcium ratio (Mg/Ca) in the calcareous shells of a group of marine microplankton called foraminifera. Two foraminifer species, Globigerinoides ruber albus and Turborotalita clarkei, are abundant in the Gulf of Aqaba, northern Red Sea, at year‐round high temperatures and salinities. The shells of these foraminifera have elevated Mg/Ca relative to other marine regions, and here, we explore the factors causing this. The Mg/Ca values of both G. ruber albus and T. clarkei reflect the environmental conditions of the water column. For G. ruber albus, temperature and salinity appear to be factors responsible for the Mg/Ca trends and elevated values. We incorporate the new Mg/Ca data for G. ruber albus to calibrate elevated Mg/Ca with temperature for high‐salinity (>40) marine environments. The Mg/Ca of the deeper dwelling T. clarkei show higher ratios following deep mixing of the surface water column and may indicate annually recurring phytoplankton blooms caused by nutrient input into the sunlit ocean surface. Key Points: A new Mg/Ca temperature calibration for high salinity environments is presented for Globigerinoides ruber albusA framework for incorporating high salinity environments into global Mg/Ca‐T calibrations is providedEnhanced Mg/Ca in subsurface dwelling Turborotalita clarkei may indicate seasonal deep mixing of the upper water column [ABSTRACT FROM AUTHOR]

The Gulf of Aqaba is considered one of the most seismotectonically active regions in the Middle East. This study analyzes the seismic activity from 1983 to 2018 to investigate the spatio-temporal distribution of the events in the Gulf's three basins. The seismic activity is characterized by conventional mainshock–aftershock sequences and swarm activity. Most activity is located in the Aragonese basin, while the Dakar basin shows less seismic activity. The b-value was calculated for the three basins from the declustered catalogue, representing the fingerprint of the transform fault. Within the Aragonese, three significant earthquakes occurred in 1993, 1995, and 2015 with moment magnitude (Mw) of 5.8, 7.2, and 5.2, respectively. An intermediate seismic quiescence preceded the three earthquakes. The quiescence time for the 1995 earthquake began at the tail of the aftershocks of the 1993 mainshock, suggesting that the two earthquakes were not entirely independent. At the tail of the 1995 earthquake aftershocks, the seismic activity spread across the Gulf, increasing in frequency and decreasing in magnitude. A similar pattern was observed for the seismic quiescence preceding the 2015 mainshock. The occurrence of the three significant and proximal earthquakes in the Aragonese region over a 22-year interval, with the described similarities, suggests a link between these earthquakes. Finally, the Coulomb stress transfer shows that the 1993 source fault seems to increase the stress loading on the 1995 left-lateral strike-slip fault, and the latter would also increase the stress transfer on the 2015 left-lateral strike-slip fault. [ABSTRACT FROM AUTHOR]

An updated checklist and status assessment of the gobioid species (Gobiiformes) in the Red Sea is provided. Of the 162 species, 141 belong to the Gobiidae, nine to Microdesmidae, five to Xenisthmidae, six to Schindleriidae and one to Kraemeriidae. The Shrimpgoby (Cryptocentrus steinhardti) and the Sand Goby (Hazeus ingressus) are reported from Eilat, Israel and Abu Dabab, Marsa Alam, Egypt. Both species, which belong to Indo-West Pacific genera, were originally described from the eastern Mediterranean Sea and were unknown from the Red Sea so far. Records of these species are based on underwater photographs. Eviota pseudostigma, a species known from islands of the Western Indian Ocean, was photographed and collected from Mangrove Bay, El Quseir, Egypt, and represents a new record for the Red Sea. Eviota oculopiperita, described from the north-eastern Red Sea was found on the western side of the Red Sea. A new record of the microdesmid fish Gunnellichthys irideus, based on underwater photographs taken from the southern Egypt, is reported. Previous records of Paragobiodon echinocephalus from the Gulf of Aqaba are regarded as misidentification of P. modestus. [ABSTRACT FROM AUTHOR]

Fishing pressure and other human impacts are increasing throughout much of the Red Sea. We assessed the minimum soak time and status of the coral reef fish community in the Aqaba Marine Park, Jordan prior to its official redesignation as a Marine Reserve in 2020 using baited remote underwater video (BRUV). A total of 86 species from 27 families were recorded in 15 deployments, comprising 60 hours of video. A minimum soak time of 150 minutes was found necessary to sufficiently estimate overall species richness. For richness of commercially valuable families, shorter soak times of 60 minutes were adequate, likely resulting from increased attraction of this largely piscivorous group to the bait plumes. A 30-minute soak time was adequate to assess the maxN of commercially valuable families. Our results indicate that the Aqaba Marine Reserve was overfished prior to its establishment as a reserve, as we recorded no large predators and not a single individual from Carcharhinidae, Haemulidae, Lutjanidae, or Scombridae. Other predator families like Epinephelinae, Lethrinidae, and Carangidae were relatively rare with low maxN. Our results provide a useful point of comparison to assess whether the coral reef fish community will recover as a result of enhanced management action and reduced fishing pressure. [ABSTRACT FROM AUTHOR]

The Gulf of Elat/Aqaba exhibits high inter‐annual variability in mixed layer depth. Observations from the northern Gulf show differences of hundreds of meters in winter mixing depth, which ranges between 300 m in years with shallow mixing and up to 700 m in years with deep mixing. Deep mixing events can occur in two consecutive years or after four consecutive years of shallow mixing. The mixing depth has an effect on the concentration of nutrients and chlorophyll (and other tracers) in the surface and deep water. Using a 3D coupled physical‐ecological model, we studied the effect of shallow versus deep mixing on the processes controlling the phytoplankton bloom and on nutrient accumulation in the deep water. We found that years with deep mixing are characterized by larger spatial variability in surface and integrated chlorophyll concentration during the mixing season. We found that horizontal advection is a dominant contributor for integrated phytoplankton concentration in years with deep mixing in the northern Gulf. Even when mixing was deep and nutrient limitation decreased, light limitation on phytoplankton integrated growth was enhanced in the north compared with the south. In addition, we showed that the nutrient accumulation in the deep water after a year with deep mixing in the northern Gulf was initially affected mostly by physical processes (such as advection and vertical mixing), and less from ecological regeneration, and switched to be dominated by ecological processes alone during the third year after mixing. Plain Language Summary: Primary production by phytoplankton is the base of the marine ecological system and is an important mechanism for the sequestration of carbon from the atmosphere into the ocean. In this work, we studied the effect of varying mixed layer depths on the mechanisms for phytoplankton bloom initiation, a phenomenon of increased phytoplankton concentration. We studied the Gulf of Elat/Aqaba, a relatively small basin, which exhibits years of shallow and very deep mixing. We found that deep mixing caused increased spatial variability in phytoplankton concentration between the northern and southern Gulf, both in the surface water and in the integrated column. Increase in mixed layer depth caused an increase in the effect of horizontal advection on the phytoplankton concentration in the whole water column in the northern Gulf. In addition, it caused light limitation on growth to increase in the northern Gulf, even though nutrients were more abundant after deep mixing. Finally, we showed that nutrient accumulation in the deep water of the northern Gulf after deep mixing, which decreased their concentration in depth, was initially mostly due to physical processes of mixing and advection, but in the third year after mixing was dominated by ecological regeneration. Key Points: Horizontal advection effect on northern Gulf integrated phytoplankton concentration increased with mixed layer deepeningDespite increased nutrient input by enhanced mixing, light remained the main limitation on northern Gulf's integrated phytoplankton growthNutrient accumulation in the deep water was driven mostly by physical processes immediately after mixing [ABSTRACT FROM AUTHOR]

Identifying areas susceptible to flash flood hazards is essential to mitigating their negative impacts, particularly in arid regions. For example, in southeastern Sinai, the Egyptian government seeks to develop its coastal areas along the Gulf of Aqaba to maximize its national economy while preserving sustainable development standards. The current study aims to map and predict flash flood prone areas utilizing a spatial analytic hierarchy process (AHP) that integrates GIS capabilities, remote sensing datasets, the NASA Giovanni web tool application, and principal component analysis (PCA). Nineteen flash flood triggering parameters were initially considered for developing the susceptibility model by conducting a detailed literature review and using our experiences in the flash food studies. Next, the PCA algorithm was utilized to reduce the subjective nature of the researchers' judgments in selecting flash flood triggering factors. By reducing the dimensionality of the data, we eliminated ten explanatory variables, and only nine relatively less correlated factors were retained, which prevented the creation of an ill-structured model. Finally, the AHP method was utilized to determine the relative weights of the nine spatial factors based on their significance in triggering flash floods. The resulting weights were as follows: rainfall (RF = 0.310), slope (S = 0.221), drainage density (DD = 0.158), geology (G = 0.107), height above nearest drainage network (HAND = 0.074), landforms (LF = 0.051), Melton ruggedness number (MRN = 0.035), plan curvature (PnC = 0.022), and stream power index (SPI = 0.022). The current research proved that AHP, among the most dependable methods for multi-criteria decision-making (MCDM), can effectively classify the degree of flash flood risk in ungauged arid areas. The study found that 59.2% of the area assessed was at very low and low risk of a flash flood, 21% was at very high and high risk, and 19.8% was at moderate risk. Using the area under the receiver operating characteristic curve (AUC ROC) as a statistical evaluation metric, the GIS-based AHP model developed demonstrated excellent predictive accuracy, achieving a score of 91.6%. [ABSTRACT FROM AUTHOR]