Extreme marine heatwave linked to mass fish kill in the Red Sea.

The coral genus Madracis has a global distribution from shallow waters to over 1200 m depth. In the Red Sea, the azooxanthellate endemic species Madracis interjecta is known to occur from depths of 120 to 350 m. This species is often observed in mesophotic ecosystems and has been reported to form sediment-binding bioherms, yet the conditions required for these formations are not understood. Here, we extracted quantitative data from video footage to identify the distribution of M. interjecta for the first time along the Saudi Arabian Red Sea coast. We present a habitat suitability model to identify potential habitats in the northern Red Sea and Gulf of Aqaba for this species. Combining presence data with geomorphometric variables and environmental data, we identified both depth and seafloor ruggedness as main drivers of this species distribution. Through multivariate statistics, we found that bioherms were found in deeper and cooler waters than individual M. interjecta colonies. Due to the narrow continental shelf and steep slopes of the northern Red Sea and Gulf of Aqaba, the effects of coastal development are threatening shallow, mesophotic and deep ecosystems. This work provides both a baseline survey and predicted distributions of an important habitat-forming scleractinian coral, which can inform conservation planning in the region.

Microplastic bioaccumulation (MPB) within marine fish through the food chain has been extensively validated in traditional experimental studies. However, the idealized conditions of these studies fail to fully capture the complex, nonlinear interactions among marine microplastics, biota, and environmental factors in real-world scenarios, and the spatiotemporal characteristics of risks are lacking in these studies, hindering the accurate assessment and control of risk. To address the above knowledge gaps, we constructed an improved sparrow search algorithm/geographic random forest (ISSA-GRF) conceptual framework and analyzed MPB in 82 common fish species from coastal ecosystems. The rate of MPB in coastal fish in 22 major marine ecosystems has increased by an average of 3.56% over the past decade. Hotspot areas such as the Red Sea coast, Gulf of Thailand coast, and Sulawesi Sea coast were identified; the bioaccumulation rates increased by 8.00%, 5.68%, and 5.34%, respectively. Ocean eutrophication, triggered by changes in nutrient levels, was revealed as the main driver via a causal analysis. These findings not only independently validate the increasing risk of microplastic biological accumulation outside the laboratory environment but also highlight the importance of controlling marine eutrophication to mitigate the biological risks associated with microplastics.

Use of the Dorsal Fin Formula for the Identification of Lethrinus (Actinopterygiidae: Lethrinidae) Species on the Red Sea Coasts of Yemen, with a Key to Species of Genus Lethrinus

Metapenaeus monoceros is the second most abundant commercially important shrimp species caught along the Saudi Arabian Red Sea coast. However, knowledge of its life history and population dynamics in the region remains limited, posing challenges for sustainable management. This study assessed the growth, maturity, and mortality of M. monoceros based on fishery-independent samples collected from shrimp trawling grounds off Al Qunfudhah and Jizan (October 2022-September 2023). Altogether, 10,859 specimens were examined, with a carapace length (CL) ranging from 7.98 to 49.10 mm and a total weight (W) in the range of 0.41 to 41.28 g. The observed sex ratio was 1.56:1 in favor of females. The CL-W relationship was W = 0.0024∙CL2.58. The seasonalized von Bertalanffy growth parameters were CL∞ = 50.66 mm, K = 0.35 year-1, tanchor = 0.43 years, C = 0.64, and ts = 0.61 years for females, and CL∞ = 38.97 mm, K = 0.55 year-1, tanchor = 0.51 years, C = 0.84, and ts = 0.39 years for males. Females reached their first sexual maturity at 21.12 mm CL. The exploitation rates (0.60 for both sexes) indicated overfishing. Spawning potential ratio analysis showed that the current fishing pressure reduces the spawning stock biomass to 23% of unexploited levels. A 50% reduction in fishing effort, extended seasonal closures, and selective gear modifications are recommended to rebuild the stock and ensure sustainability.

Around the world, sponges play a significant role in marine ecosystems, and a wide variety of sponge species can be found in the coast of Red Sea of Saudi Arabia. The unique environmental conditions of the Red Sea, including warm, oligotrophic water and high salinity, have encouraged the growth of abundant sponge fauna. Our study aims to investigate the biodiversity, taxonomic composition, and phylogenetic relationships of eukaryotic organisms linked with sponges in the Red Sea off the coast of Saudi Arabia and infer the possible ecological roles and functional contributions of the identified eukaryotic taxa to sponge health and ecosystem functioning. The study investigated the microbial diversity, focusing on the genera Hyalosynedra sp., Navicula sp., Papiliocellulus sp., Psammodictyon sp., Pynococcus sp., Ostreococcus sp., Micromonas sp., and other unclassified species. Our metagenomic analysis and phylogenetic evaluation revealed a deep and diverse microbial community, with each genus performing significant ecological roles, including nutrient cycling, primary production, and contributing to marine food networks. Moreover, these genera display promising biotechnological prospects, including uses in bioremediation, biofuel production, and the synthesis of high-value biomolecules. Comparative analysis with other marine regions has focused on both the similarities and unique aspects of the Red Sea microbial community, which are influenced by its distinct environmental conditions. The gained findings contribute to a deeper understanding of the ecological dynamics in the Red Sea and open new avenues for biotechnological exploration in marine ecosystems.

Studies on water-associated bird communities within seagrass and mangrove habitats, especially in arid environments, are limited. Here, we studied a pristine mangrove forest with associated seagrass meadows in the Jazan City for Primary and Downstream Industries (JCPDI) on the southern Red Sea coast of Saudi Arabia. Our objectives were to (1) determine the differences in the diversity and distribution of water-associated bird communities between three sampling stations—S1 (a mixture of mangroves and seagrass beds), S2 (an open coast adjacent to mangroves), and S3 (an open coast without vegetation)—and across three seasons (March for spring, July for summer, and November for fall), and (2) identify the key climatological variables influencing variations in waterbird community composition. Point count surveys detected 29 water-associated bird species from 14 families. The Common Gull Larus canus and the Kentish Plover Anarhynchus alexandrinus were the most commonly observed waterbird species. Station S1 exhibited higher species richness, diversity, and dominance compared to stations S2 and S3, with a downward trend from S1 to S3, except in summer. The non-metric multidimensional scale (nMDS) and the analysis of similarity (ANOSIM) showed that seasonality was a major factor in avifaunal composition. A distance-based linear model (DISTLM) revealed that air temperature was the most influential factor affecting species composition. We concluded that the synergistic effects of a partially enclosed embayment, dominated by seagrass meadows and mangrove forests, support greater bird diversity than exposed, less vegetated coastal habitats.

Studies on water-associated bird communities within seagrass and mangrove habitats, especially in arid environments, are limited. Here, we studied a pristine mangrove forest with associated seagrass meadows in the Jazan City for Primary and Downstream Industries (JCPDI) on the southern Red Sea coast of Saudi Arabia. Our objectives were to (1) determine the differences in the diversity and distribution of water-associated bird communities between three sampling stations—S1 (a mixture of mangroves and seagrass beds), S2 (an open coast adjacent to mangroves), and S3 (an open coast without vegetation)—and across three seasons (March for spring, July for summer, and November for fall), and (2) identify the key climatological variables influencing variations in waterbird community composition. Point count surveys detected 29 water-associated bird species from 14 families. The Common Gull Larus canus and the Kentish Plover Anarhynchus alexandrinus were the most commonly observed waterbird species. Station S1 exhibited higher species richness, diversity, and dominance compared to stations S2 and S3, with a downward trend from S1 to S3, except in summer. The non-metric multidimensional scale (nMDS) and the analysis of similarity (ANOSIM) showed that seasonality was a major factor in avifaunal composition. A distance-based linear model (DISTLM) revealed that air temperature was the most influential factor affecting species composition. We concluded that the synergistic effects of a partially enclosed embayment, dominated by seagrass meadows and mangrove forests, support greater bird diversity than exposed, less vegetated coastal habitats.

Abstract Bathymetric mapping is vital for navigation, coastal management, and marine habitat assessment. Traditional methods use satellite reflectance data and machine learning (ML), supported by echo-sounding field data. This study explores the underutilized potential of chlorophyll concentration for water depth inference, introducing it as a novel alternative for bathymetry and highlighting advanced ML techniques for improved mapping precision. The novel approach, applied at two sites in Egypt, Jemsha region (Gulf of Suez coast) and New Heaven Resort (south of Marsa Alam on the Red Sea coast), uses two main strategies. First, water depth was estimated from MODIS satellite chlorophyll data and validated with echo-sounding field data, yielding an RMSE of 1.5 m, R2 of 0.55, and precision of 0.836 for Jemsha, and an RMSE of 2.5 m, R2 of 0.1, and precision of 0.979 for New Heaven. Second, water depth was derived from Sentinel-2 satellite reflectance data using a new ensemble ML (EM) technique, refined from three well-known bathymetry models, and validated similarly. Results showed an RMSE of 1.3 m, R2 of 0.5, and precision of 0.836 for Jemsha, and an RMSE of 2 m, R2 of 0.3, and precision of 0.979 for New Heaven. These findings are globally significant, addressing bathymetric data scarcity in areas with limited field data or logistical constraints, while advancing methods for sustainable coastal management and marine conservation.

Analyzing the filleting attributes of fish is essential for evaluating the commercial viability of fish products. This study assesses the filleting attributes, length-weight relationships, and condition factors of three commercially important fish species (Lethrinus nebulosus, Epinephelus tauvina, and Plectorhinchus gaterinus) from the Yanbu fish market in Saudi Arabian Red Sea coast. Fillet production results indicated a decreasing trend in edible portions among these species, with Lethrinus nebulosus yielding the most, followed by Plectorhinchus gaterinus and Epinephelus tauvina. Fish with smaller heads and medium-sized skeletons produced higher edible fillet yields. Linear regression analysis revealed no significant differences, establishing a linear correlation between net edible weight and fillet yield. The length-weight relationship analyses for Lethrinus nebulosus, Plectorhinchus gaterinus, and Epinephelus tauvina indicated positive allometric growth. Condition factor analysis showed that Lethrinus nebulosus had the lowest mean condition factor (1.05±0.05), while Epinephelus tauvina had the highest mean condition (1.67±0.15). A robust association between weight and fillet yield components was also observed. These findings enhance our understanding of the biological and economic characteristics of these species along the Yanbu coastline, supporting fisheries management and postharvest research in line with conservation and restoration efforts. Keywords: Condition factor, Edible weight, Filleting yield, Fish products, Postharvest characteristics.

Ecological and health risk assessment of Sharm El-sheikh beach sediments, Red Sea coast.

Evaluation of Physicochemical Characteristics of Aquatic Environment for Mangrove Communities on the Red Sea Coast, Egypt

Multi-temporal satellite image analysis for detecting the changes in mangrove vegetation between Allith and Alqahma on the Red Sea coast.

The Western Pygmy Blue Brephidium exilis (Boisduval), a North American butterfly that began its overseas expansion in Arabia more than thirty years ago, was recently observed for the first time at two sites in the western part of the Kingdom of Saudi Arabia: (i) a wintertime record of a few individuals in near-freezing temperatures at a peri-agricultural site outside the northwestern desert city of Tabuk, and (ii) a large population among extensive urban landscaping along the central Red Sea coast north of Jeddah, similar to sites where it flourishes in eastern Arabia. These observations (a) fill a large observational gap in the expanding range of this non-native species in the Middle East, South-west Asia and even North Africa; (b) demonstrate the breadth of its ecological tolerance; and (c) indicate its potential for continued dispersal, including the possibility that it may already be established at other urban sites in the growing cities in the west of the Kingdom.

Aedes aegypti, the primary vector of several medically significant arboviruses-including dengue fever, yellow fever, chikungunya and Zika-was successfully eradicated from Egypt in 1963. However, since 2011, there have been increasing reports of its re-emergence, alongside dengue outbreaks in southern Egyptian governorates, raising significant public health concerns. This study aimed to model the current and future distribution of Ae. aegypti in Egypt. Local occurrence data were integrated with bioclimatic, anthropogenic and biological environmental variables to identify key factors influencing the distribution of Ae. aegypti. Maximum entropy (MaxEnt) modelling demonstrated strong predictive performance (area under the receiver operating characteristic curve [AUC] mean = 0.975; true skill statistic [TSS] mean = 0.789). The key determinants of habitat suitability were identified as human population density, annual precipitation and the normalised difference vegetation index (NDVI). Current predictions indicate that suitable habitats for Ae. aegypti are concentrated in the Nile Valley, Nile Delta, Fayoum Basin, Red Sea coast and South Sinai. Projections under future climate change scenarios suggest an expansion of suitable habitats, particularly in the Nile Delta region. By 2050, the model predicts a 61%-68% increase in suitable habitat area, with a further 64%-69% increase by 2070, depending on the future climate scenarios. These findings are crucial for informing vector control and disease prevention strategies, particularly considering Egypt's status as one of the world's leading tourist destinations.

One of the biggest economic and social concerns of the century will be the issues of water resources in the arid regions of the Mediterranean, where mismanagement of water resources is a threat to sustainable development. Egypt is one of the nations that will face significant issues due to its steady portion of the Nile water. Climate change influences the spatial and temporal distribution of water supplies and the amount of crop evapotranspiration. In addition, water use in agriculture is by far the highest and is frequently criticized as being the least efficient. So, gaining more output per unit of utilized water is the idea behind improving agricultural water productivity. Identifying water resources and improving water productivity techniques are essential in making the most effective use of agriculture in the Mediterranean regions. Freshwater resources in Egypt include the flow of the Nile, precipitation, and groundwater. Egypt also uses a variety of low-quality water sources including treated wastewater and agricultural drainage water, and desalination is also utilized to provide residential water for several regions along the Mediterranean and Red Sea coasts. In this paper, water resources in Egypt, its irrigation systems, methods of water-saving and improving water productivity are discussed.

The article is devoted to the struggle of world and regional powers for Sudan, where the armed conflict between the Sudanese army and the Rapid Support Forces has been going on for a long time, acting as rebels against the legitimate authorities of this country. The main focus is on the approaches of Russian diplomacy to solving this problem from the perspective of Russia's military, political and economic interests in Sudan, with which Russia has long-standing historical relations. Moscow's desire to establish a naval base in Port Sudan on the Red Sea coast is noted to ensure the Russian presence in the region and its use for cargo transit to the countries of the Sahara-Sahel zone in connection with the possible loss of Russian bases in Syria after the overthrow of the government of Bashar al-Assad there. The issue of the difficult balancing of Russian diplomacy between various political forces in Sudan and their allies against the background of the growing interest of the United States in this country is particularly considered.

In recent decades, water shortages have become a significant problem. Sudan is no exception. In addition to the main towns of Port Sudan and Suakin, many villages scattered along the Red Sea coast also experience severe shortages of fresh water and electricity supply. The problem recently worsened after the Arbaat Dam's collapse, which was Port Sudan's main source of fresh water. Desalination of seawater and brackish water can play a significant role in addressing this issue. In this field, reverse osmosis (RO) is predominant due to its many advantages. However, this technology consumes a significant amount of energy. In many places around the world, freshwater shortages are accompanied by an abundance of solar energy. In this study, one of the existing desalination plants in Port Sudan was considered to investigate the possibility of shifting it to run on solar power instead of electricity from the national grid, or that generated by diesel engines. The plant under study is a small RO unit with a capacity of 7 m3/h. It consumes energy at a rate of 6.6 kWh/m3. PVsyst software has been used to design and simulate the solar photovoltaic system which can drive the desalination unit. Results showed that with a PV array total power of 95.2 kW and 9360 Ah battery capacity, the system can work steadily for 7 hours daily to produce 49 m3/day of fresh water. The solar system's p annual performance ratio (PR) is 60.3% with a solar fraction equal to 100%. While the simple payback period (SPB) for the photovoltaic system is found to be 1.74 years.

The Red Sea coast is overcrowded by many international and local harbors, particularly Shalateen harbor, that imposes environmental threats on the marine biota. The Shalateen ecosystem is assessed using benthic foraminifera, a sensitive proxy to environmental change. This study investigated the relationship between ecological parameters and benthic foraminifera distribution in the Shalateen site, a coastal area on the Red Sea facing increasing environmental deterioration. A total of 17 stations were sampled, and their benthic foraminiferal contents were analyzed. The findings revealed enriched benthic foraminiferal assemblages, dominated by Miliolida and Rotaliida, where counted morphological deformities in foraminiferal tests were observed and counted. Siamese twins, wrong direction of coiling, and aberrant chambers are the depicted test abnormalities. They are higher in the miliolids than rotaliids. A statistical analysis identified two distinct foraminiferal assemblages; group 1 is associated with shallow, high-energy habitats with elevated salinity and carbonate content, while group 2 occupies deeper waters with higher organic matter and finer sediments. The environmental-based foraminiferal indices (FAI, FI, FMI and AEI) highlighted that the stations in the nearby harbor have higher environmental impacts than the offshore stations. These findings provide crucial baseline data for future environmental management and conservation efforts in this vulnerable ecosystem.

Sharm Obhur, situated approximately 35 km north of Jeddah City along the Red Sea coast, is a prominent recreational area with diverse benthic habitats. Accurate mapping of seabed sediments is critical for characterizing marine ecosystems and elucidating benthic habitat distribution in this region. This study underscores the importance of assessing sediment distribution patterns in Sharm Obhur, particularly due to the prevalence of recreational activities and navigational traffic. This research investigates sediment dynamics in Sharm Obhur, a coastal creek near Jeddah, utilizing Multibeam Echo Sounder (MBES) backscatter data and grab sample analyses. The study focuses on understanding sediment distribution patterns and their implications for coastal management. MBES technology provides high-resolution data on seafloor composition and roughness, essential for assessing sediment types and bedforms. Through spatial alignment of MBES data with ground truth sediment samples, we analyze sediment characteristics and validate findings. Results indicate predominant sand presence with detectable mud in deeper channels and northern anthropogenically impacted areas. Gravel deposits correlate with coral formations near the creek edges. Tidal influence is evident, with increased sand presence at the creek entrance. The study demonstrates MBES backscatter's efficacy in mapping sediment distributions and seabed characteristics, benefiting marine science and coastal management. This research enhances knowledge of sediment transport processes, facilitating informed decision-making for sustainable coastal development and conservation efforts.