Fisheries of the Red Sea and the Arabian Gulf: A Comparative Assessment

Globalization has significantly accelerated maritime transportation, which serves as one of the primary pathways for the introduction of non-indigenous species (NIS) into new marine environments. Once established, these species can become invasive, threatening biodiversity, ecosystem services, and local economies. Effective management of NIS requires a comprehensive understanding of species distributions, environmental factors, and potential introduction pathways. This study, conducted in 2023-2024 by the National Center for Wildlife (NCW) in collaboration with the King Abdullah University of Science and Technology (KAUST), provides the first comprehensive assessment of non-indigenous marine species in the Red Sea and the Arabian Gulf. The study aimed to establish baseline data to guide biosecurity management strategies and inform the development of a region-specific biosecurity framework/program.A multi-method approach was employed, including a literature review, maritime traffic risk assessment, and field sampling. PVC settlement panels were deployed for three months at 34 locations in the Red Sea and Arabian Gulf between 1-2 meters depth to assess biofouling communities. Data collected from each location included environmental parameters such as salinity, temperature, dissolved oxygen, pH, and weather conditions. Water samples were analyzed for nutrient concentrations, chlorophyll-a, and eDNA to further characterize local biodiversity. Specimens were identified by taxonomic experts and subjected to DNA barcoding to create a reference library. The study also assessed maritime traffic patterns to determine potential NIS introduction risks.The literature review identified 181 potential NIS species in the Red Sea and 168 in the Arabian Gulf. Based on maritime traffic data and modeling techniques, our findings showed that regions with high maritime traffic and environmental similarity, such as the Sunda Shelf, East China Sea, and Mediterranean, posed the greatest NIS introduction risks to both seas. Key hotspot ports for NIS introductions in the Arabian Gulf include Fujairah, Jebel Ali, and Ras Laffan, while ports in the Red Sea include Jeddah, Sokhna, and Port Sudan.The findings underscore the urgency for a biosecurity framework to mitigate the risks associated with the introduction of NIS in these regions. In response, the NCW is leading efforts to develop and implement a tailored biosecurity framework aligning with the Cartagena Protocol on Biosafety to the Convention on Biological Diversity and Nagoya Protocol to safeguard marine ecosystems and biodiversity in the Arabian Gulf and Red Sea. This study provides essential data that will inform future regional biosecurity strategies in the Red Sea and Arabian Gulf, supporting the protection of the associated critical marine ecosystems from invasive species.

AimThe Red Sea is characterised by a unique fauna and historical periods of desiccation, hypersalinity and intermittent isolation. The origin and contemporary composition of reef‐associated taxa in this region can illuminate biogeographical principles about vicariance and the establishment (or local extirpation) of existing species. Here we aim to: (1) outline the distribution of shallow water fauna between the Red Sea and adjacent regions, (2) explore mechanisms for maintaining these distributions and (3) propose hypotheses to test these mechanisms.LocationRed Sea, Gulf of Aden, Arabian Sea, Arabian Gulf and Indian Ocean.MethodsUpdated checklists for scleractinian corals, fishes and non‐coral invertebrates were used to determine species richness in the Red Sea and the rest of the Arabian Peninsula and assess levels of endemism. Fine‐scale diversity and abundance of reef fishes within the Red Sea were explored using ecological survey data.ResultsWithin the Red Sea, we recorded 346 zooxanthellate and azooxanthellate scleractinian coral species of which 19 are endemic (5.5%). Currently 635 species of polychaetes, 211 echinoderms and 79 ascidians have been documented, with endemism rates of 12.6%, 8.1% and 16.5% respectively. A preliminary compilation of 231 species of crustaceans and 137 species of molluscs include 10.0% and 6.6% endemism respectively. We documented 1071 shallow fish species, with 12.9% endemic in the entire Red Sea and 14.1% endemic in the Red Sea and Gulf of Aden. Based on ecological survey data of endemic fishes, there were no major changes in species richness or abundance across 1100 km of Saudi Arabian coastline.Main conclusionsThe Red Sea biota appears resilient to major environmental fluctuations and is characterized by high rates of endemism with variable degrees of incursion into the Gulf of Aden. The nearby Omani and Arabian Gulfs also have variable environments and high levels of endemism, but these are not consistently distinct across taxa. The presence of physical barriers does not appear to explain species distributions, which are more likely determined by ecological plasticity and genetic diversity.

Plankton of the Red Sea and the Arabian Gulf

In numerous Middle Eastern carbonate reservoirs, peloidal wackestone, packstone, and grainstone facies deposited in shallow-marine environments are rock types with excellent pore storage potential in microporous and micritized grains. While the origin of microporosity has been studied extensively, the process of early marine micritization remains unclear. One hypothesis suggests that early marine micritization first alters carbonate microtextures, which then facilitates the formation of micro spar and micropores in the micritized sediments during later subsurface diagenesis. Therefore, a better understanding of the origin and spatial distribution of micritized sediments is essential for accurately predicting the distribution of microporosity in limestones. This study examines micritization products in shallow-marine carbonate sediments from four lagoons on the Arabian plate coast: the Red Sea, the Arabian Sea, and the Arabian/Persian Gulf. Micritized grains are identified and characterized using optical and backscattered scanning electron microscopy. Petrographic observations are compared and correlated with oceanographic and environmental parameters to identify micritization styles and environmental conditions at a regional scale. The findings present several key insights: i) cryptocrystalline micritic microtextures are heterogeneous, characterized by a combinations of microborings and various microborings infill materials, ii) Red Sea and Arabian Gulf sediments are primarily made up of micritized grains, with about 60% of the grains being micritized grains or peloids, whereas Arabian Sea coast sediments are mainly microbored with minimal infill of endolithic tunnels and rare cryptocrystalline microtextures, and iii) the arid climate and warm, restricted oligotrophic seawater of the Red Sea and Arabian Gulf promote micritization. Conversely, the cooler seawater of the Arabian Sea relative to Red Sea and Arabian Gulf, largely open to the Indian Ocean and influenced by the southeast Asian monsoon and associated upwelling currents, promotes intense endolithic activity but limited boring infilling (incomplete micritization). Hence, we show for the first time that the early marine and microbial diagenetic process of micritization relate to a well-defined set of parameters of a regional environmental and oceanographic settings, corresponding to those that also promote the tropical-biochemical carbonate factory.

Regional variability in remotely sensed data with respect to the distribution of some snapper fishes (Family: Lutjanidae) between the Red Sea and the Arabian Gulf

The Red Sea is a large marine ecosystem in which biological research has been considerable but integrated environmental assessment insubstantial. Approximately 1400 coastal and offshore (i.e. island) sites in the Saudi Arabian Red Sea were examined and an analysis of ordinal data on the abundance of ecosystems and magnitude of human uses/environmental impacts was conducted. Mangroves, seagrasses, other floral groups and terrestrial mammals were significantly more abundant at the coastal sites than offshore. The coastal sites were also impacted most heavily, while reefs, birds, turtles and marine mammals were significantly more abundant in offshore areas. Latitudinal trends include significantly increased abundance of mangroves and seagrasses (and other flora) towards the southern Red Sea, and a decrease in abundance of reefs. Significantly higher levels of beach oil were encountered towards the northern Red Sea, probably reflecting its greater proximity to the Gulf of Suez. Cluster analysis using all biological data revealed distinctive groupings which separated according to latitude. The biogeographic patterns are comparable to those observed in previous studies for seagrasses and other communities.Using a relational database, applications of the findings to coastal management include creation of environmental profiles for particular sites or sectors, identification of resource-use conflict areas, and selection of representative sites for protected areas. Comparison with data from a complementary investigation in the Arabian Gulf indicates that the Red Sea is less perturbed by human activities than the Arabian Gulf. However, it is also evident that the Red Sea is no longer a pristine environment.

Abstract. During the last decades, the coastal areas of the Kingdom of Saudi Arabia, on the Red Sea and the Arabian Gulf, have been subjected to intense economic and industrial growth. As a result, it may be expected that the overall environmental status of Saudi Arabian coastal marine waters has been affected by human activities. As a consequence, adequate management of the Saudi Arabian coastal zone requires an assessment of how the various pressures within this zone impact the quality of seawater and sediments. To this end, environmental surveys were conducted over 15 hotspot areas (areas subject to environmental pressures) in the Saudi Arabian coastal zone of the Red Sea and over three hotspot areas in the Saudi Arabian waters of the Arabian Gulf. The survey in the Red Sea, conducted in June/July 2021, acquired measurements from hotspot areas spanning most of the Saudi coastline, extending from near the Saudi–Jordanian border in the north to Al Shuqaiq and Jizan Economic City (close to the Saudi–Yemen border) in the south. The survey in the Arabian Gulf, carried out in September 2021, included the areas of Al Khobar, Dammam and Ras Al Khair. The main objective of both cruises was to record the physical and biogeochemical parameters along the coastal waters of the kingdom, tracing the dispersion of contaminants related to specific pressures. Taken together, these cruises constitute the first multidisciplinary and geographically comprehensive study of contaminants within the Saudi Arabian coastal waters and sediments. The measurements acquired revealed the influence of various anthropogenic pressures on the coastal marine environment of Saudi Arabia and also highlighted a strong influence of hydrographic conditions on the distribution of biochemical properties in the Red Sea and the Arabian Gulf. The data can be accessed at SEANOE https://doi.org/10.17882/96463 (Abualnaja et al., 2023), whereas the details of the sampling stations are available at https://mcep.kaust.edu.sa/cruise-postings (last access: 25 March 2024). The dataset includes the parameters shown in Tables 1a, b and 2a.

Bin-Salman SA, Amasha RH, Jastaniah SD, Aly MM, Altaif K. 2018. Isolation, molecular characterization and extracellular enzymatic activity of culturable halophilic bacteria from hypersaline natural habitats. Biodiversitas 19: 1828-1834. Saline habitats, like the Dead Sea, are unusual extreme environments, due to their extreme salinity. Most saline habitats originate from the evaporation of seawater, and have a nearly neutral to slightly alkaline pH (such as the Red Sea (pH8.3) and Arabian Gulf, pH8.3). Ten halophilic bacterial strains (two Gram-negative) belonging to the family of Halomonadaceae and (eight Gram-positive), belonging to the family of Bacillaceae, were isolated from the Red Sea, Arabian Gulf, and Dead Sea by subjecting the isolates to a high salinity medium, followed by identification using 16S rRNA gene sequencing. Four of isolates were designated on the basis of their tolerance to high salinity; SBR1 exhibited 97% homology to Halomonas aquamarina, SBR2 showed 97% homology to Sediminibacillus sp., (Red Sea), SBA9 exhibited 94% homology to Halobacillus sp., (Arabian Gulf) and SBD17 gave 98% homology to Halobacillus dabanensis (Dead Sea). The isolates were also characterized by their physiological parameters, SBR1 showed optimum growth at 30°C, pH8.5 and1.5M NaCl, SBR2 at 30°C, pH6.0 and 1M NaCl. Optimum conditions for SBA9 were 35°C, pH6.5 and 1M NaCl and for SBD17, 37°C, pH7.0 and 1M NaCl.

Mohammed A. QURBAN1*, Lotfi J. RABAOUI1, Abdulnasser S. AL QUTUB1, Silvia AROSSA1, Afrah ALOTHMAN1, Eman SABBAGH1, Carlos GARCIA-SAEZ1,1National Center for Wildlife, Riyadh, Saudi Arabia* Correspondence: mqurban@ncw.gov.sa Seldom is the strong link that exists between Marine Spatial Planning (MSP) and Marine Protected Areas (MPAs) explicitly recognised as is now being done by the National Center for Wildlife (NCW). MSP is the process by which the use of marine space is identified and used to inform development decisions made by regulators. Marine Protected areas that are important for marine conservation are a priority for the NCW. These marine areas are formally designated and have legal protection as MPAs. Where MPAs do not exist in the Saudi Red Sea or the Arabian Gulf, marine plans are of assistance in the identification of areas where they could be sited optimally; taking into account environmental, social, economic and political considerations and existing uses. The Kingdom of Saudi Arabia, has been leading an intensive and extensive effort though the NCW designing and implementing MPAs, and developing a Marine Spatial Planning strategy in both the Arabian Gulf and the Red Sea as part of the Saudi Green Initiative and its 30x30 commitment to contribute to the Kunming-Montreal Global Biodiversity framework, bringing together synergies between Marine Protected Areas and Marine Spatial Planning. Areas such as Farasan Islands Man and Biosphere Reserve and the newly declared Blue Holes and Ras Hatiba in the Red Sea, and the proposed World Heritage site in Gulf of Aqaba and the Northern Red Sea and Jubail and Ras Abu Khamis in the Arabian Gulf are part of these endeavours. MSP includes elements of zoning, with MPAs incorporated as areas where the conservation of biodiversity is a priority. The development of this system of MSP will expand the role and design of individual and networks of MPAs and clarify this role to other user groups and help to reduce conflicts of use and take into account cumulative effects of marine activities to develop a sustainable and resilient-based management of the Kingdom of Saudi Arabia waters.

Abstract. We present shipborne measurements of NOx (≡ NO + NO2) and NOy (≡ NOx+ gas- and particle-phase organic and inorganic oxides of nitrogen) in summer 2017 as part of the expedition “Air Quality and climate change in the Arabian BAsin” (AQABA). The NOx and NOz (≡ NOy-NOx) measurements, made with a thermal dissociation cavity ring-down spectrometer (TD-CRDS), were used to examine the chemical mechanisms involved in the processing of primary NOx emissions and their influence on the NOy budget in chemically distinct marine environments, including the Mediterranean Sea, the Red Sea, and the Arabian Gulf, which were influenced to varying extents by emissions from shipping and oil and gas production. Complementing the TD-CRDS measurements, NO and NO2 data sets from a chemiluminescence detector (CLD) were used in the analysis. In all regions, we find that NOx is strongly connected to ship emissions, both via direct emission of NO and via the formation of HONO and its subsequent photolytic conversion to NO. The role of HONO was assessed by calculating the NOx production rate from its photolysis. Mean NO2 lifetimes were 3.9 h in the Mediterranean Sea, 4.0 h in the Arabian Gulf, and 5.0 h in the Red Sea area. The cumulative loss of NO2 during the night (reaction with O3) was more important than daytime losses (reaction with OH) over the Arabian Gulf (by a factor 2.8) and over the Red Sea (factor 2.9), whereas over the Mediterranean Sea, where OH levels were high, daytime losses dominated (factor 2.5). Regional ozone production efficiencies (OPEs; calculated from the correlation between Ox and NOz, where Ox= O3+ NO2) ranged from 10.5 ± 0.9 to 19.1 ± 1.1. This metric quantifies the relative strength of photochemical O3 production from NOx compared to the competing sequestering into NOz species. The largest values were found over the Arabian Gulf, consistent with high levels of O3 found in that region (10–90 percentiles range: 23–108 ppbv). The fractional contribution of individual NOz species to NOy exhibited a large regional variability, with HNO3 generally the dominant component (on average 33 % of NOy) with significant contributions from organic nitrates (11 %) and particulate nitrates in the PM1 size range (8 %).

Abstract. Atmospheric non-methane hydrocarbons (NMHCs) have been extensively studied around the globe due to their importance to atmospheric chemistry and their utility in emission source and chemical sink identification. This study reports on shipborne NMHC measurements made around the Arabian Peninsula during the AQABA (Air Quality and climate change in the Arabian BAsin) ship campaign. The ship traversed the Mediterranean Sea, the Suez Canal, the Red Sea, the northern Indian Ocean, and the Arabian Gulf, before returning by the same route. The Middle East is one of the largest producers of oil and gas (O&G), yet it is among the least studied. Atmospheric mixing ratios of C2–C8 hydrocarbons ranged from a few ppt in unpolluted regions (Arabian Sea) to several ppb over the Suez Canal and Arabian Gulf (also known as the Persian Gulf), where a maximum of 166.5 ppb of alkanes was detected. The ratio between i-pentane and n-pentane was found to be 0.93±0.03 ppb ppb−1 over the Arabian Gulf, which is indicative of widespread O&G activities, while it was 1.71±0.06 ppb ppb−1 in the Suez Canal, which is a characteristic signature of ship emissions. We provide evidence that international shipping contributes to ambient C3–C8 hydrocarbon concentrations but not to ethane, which was not detected in marine traffic exhausts. NMHC relationships with propane differentiated between alkane-rich associated gas and methane-rich non-associated gas through a characteristic enrichment of ethane over propane atmospheric mixing ratios. Utilizing the variability–lifetime relationship, we show that atmospheric chemistry governs the variability of the alkanes only weakly in the source-dominated areas of the Arabian Gulf (bAG=0.16) and along the northern part of the Red Sea (bRSN=0.22), but stronger dependencies are found in unpolluted regions such as the Gulf of Aden (bGA=0.58) and the Mediterranean Sea (bMS=0.48). NMHC oxidative pair analysis indicated that OH chemistry dominates the oxidation of hydrocarbons in the region, but along the Red Sea and the Arabian Gulf the NMHC ratios occasionally provided evidence of chlorine radical chemistry. These results demonstrate the utility of NMHCs as source/sink identification tracers and provide an overview of NMHCs around the Arabian Peninsula.

A total of 1217 fish species were analysed and the percentage of species in each of a number of zoogeographic patterns was calculated. An additional two categories, Atlanto-Mediterranean (anti-Lessepsian and mariculture escapees) and two cichlid species, were not included in our calculations. The present paper presents the division of the Red Sea indigenous ichthyofauna into the following categories: Red Sea endemic (15.1%), Red Sea and Oman, Aden, and Arabian Gulf (12.7%), Red Sea and Western Indian Ocean (8.6%), Red Sea and Indian Ocean (5.2%), Red Sea and Indo-Pacific (53.3%) and Red Sea and circumglobal (5.1%). The opening of the Suez Canal in 1869 resulted in a massive migration of Red Sea biota into the Mediterranean, among them 104 fish species. Several studies have attempted to determine whether there are traits that correlate with success in colonization of the Mediterranean by Red Sea fishes (Lessepsian migration). The results of our study demonstrate similar zoogeographic distribution patterns between the Red Sea ichthyofauna and those of the Lessepsian migrants. Thus, no correlation was found between wide-range distribution and success in colonization of the Mediterranean by Red Sea fish species, via the Suez Canal.

The present chapter explores the seasonal, interannual, and long-term sea-level changes in the Arabian Gulf. Tides, winds, and density-driven currents are the primary drivers of circulation in the Arabian Gulf. The sea level is relatively high during fall and low during spring, with a maximum during November and a minimum during April. The sea-level variability in the Arabian Gulf is considerably different from or nearly opposite to the pattern of sea-level changes in the adjacent marginal basin (Red Sea). Using Principal Component Analysis, the analysis of low-passed sea-level has shown that the first mode of variability explains 87.9% of the long-term variability. Long-term linear sea-level trends in the Northern Arabian Gulf are 2.58 mm/year and 3.14 mm/year, respectively, with an overall average of 2.92 mm/year. The long-term linear trend in sea-level for the post-2000 period at the northern and southern regions are 4.06 mm/year and 4.44 mm/year, respectively, with a basin average trend of 4.29 mm/year. The numerical estimates for the RCP2.6, RCP4.5, and RCP8.5 scenarios reveal a predicted rise in sea level in the Arabian Gulf of 8.1 cm, 1.3 cm, and 6.8 cm by 2050, and 16.9 cm, 17.7 cm, and 39.1 cm by the end of the century, respectively.

The availability of nearly three decades of sea-level estimates from satellite altimetry, for the period from 1993 to the present, is exploited for understanding the climatology of sea level and its long-term variability in the Arabian Gulf (also known as the Persian Gulf) in comparison with global oceans. The Arabian Gulf is characterized by a lower sea level from February to May and a higher sea level from September to December, with a maximum in November and a minimum in April. The variability of sea level in the Arabian Gulf is significantly different and nearly opposite to the pattern of sea-level changes in the adjacent marginal basin, the Red Sea. The analysis of low-passed sea level using the empirical orthogonal function and principal component analysis showed that the first mode of variability explains 87.9% of the long-term variability and the second mode explains nearly half of the remaining variability (5.6%). The linear long-term trends in sea level are 2.58 mm/year for the Northern Arabian Gulf and 3.14 mm/year for its southern part, with an average of 2.92 mm/year for the entire Gulf. The analysis of sea level in the Arabian Sea showed a faster rate of sea level rise in the post-2000 period. The long-term linear trend for the post-2000 period in the Northern Arabian Gulf is 4.06 mm/year, and in the southern Gulf it is 4.44 mm/year, with an average trend of 4.29 mm/year. Under the RCP2.6, RCP4.5, and RCP8.5 scenarios, the numerical projections show an expected rise in sea level in the Arabian Gulf by 8.1, 1.3, and 6.8 cm by 2050, and by 16.9, 17.7, 39.1 cm, respectively by the end of the 21st century.

Records of Indo-Pacific humpback dolphin sight-ings, strandings, and museum specimens in the Arabian region were compiled and used to review the distribution and status of this species. Nominal usage of Sousa chinensis (Osbeck, 1765) has been retained as a pragmatic measure, although the species present in the region resembles Sousa plumbea (Cuvier, 1828). Little is known about the ecology of this species in the region. Most available information on S. chinensis in the region originates from the Sultanate of Oman, where this species is among the most commonly recorded cetaceans; however, there is no absolute measure of abundance for anywhere in the region and the status of the species is unknown. Distribution is described for the region to include much of the Arabian (Persian) Gulf, Arabian Sea, Gulf of Aden, and Red Sea, but notably excludes the Gulf of Oman. This discontinuous distribution suggests the possible presence of discrete popu-lations within the region. Beach-cast/dead indi-viduals represent nearly two-thirds of all records (n=303) of this species in Oman. Live sightings indicate unusually large group sizes (up to 100 individuals) in the Arabian Sea and Arabian Gulf. Occasional associations with Tursiops sp. and Delphinus capensis tropicalis were documented. Mating behavior and the presence of calves were recorded in the months of April and May, and calves were also reported in June, October, November, and December. Threats to humpback dolphins in the Arabian region include incidental capture in fishing nets, coastal and offshore devel-opment (e.g., land reclamation, dredging, port and harbor construction), pollution, boat traffic, oil and gas exploration (including seismic survey-ing), military exercises, and biotoxins associated with red tide events. Evidence for historic and current directed catches of S. chinensis is limited, but opportunistic hunting may occur. Intraspecific variation in cranial measurements of individuals from the Arabian Sea coast of Oman fall within relative values found in individuals from the Saudi Arabian Gulf coast. Cranial abnormalities were few. Recommendations are made for conserva-tion management-oriented research focusing on stock identity and status assessments, as well as for monitoring of fisheries by-catch, clearer defi-nition of other threats, continued specimen and sample collection, and training of local scientists.Key Words: Humpback dolphin, Sousa, Arabia, Persian Gulf, Middle East, Oman, distribution, abundancy conservation