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Aim: Coral reefs rely on the symbiosis between scleractinian corals and intracellular, photosynthetic dinoflagellates of the genus Symbiodinium making the assessment of symbiont diversity critical to our understanding of ecological resilience of these ecosystems. This study characterizes Symbiodinium diversity around the Arabian Peninsula, which contains some of the most thermally diverse and understudied reefs on Earth. Location: Shallow water coral reefs throughout the Red Sea (RS), Sea of Oman (SO), and Persian/Arabian Gulf (PAG). Methods: Next-generation sequencing of the ITS2 marker gene was used to assess Symbiodinium community composition and diversity comprising 892 samples from 46 hard and soft coral genera. Results: Corals were associated with a large diversity of Symbiodinium, which usually consisted of one or two prevalent symbiont types and many types at low abundance. Symbiodinium communities were strongly structured according to geographical region and to a lesser extent by coral host identity. Overall symbiont communities were composed primarily of species from dade A and C in the RS, clade A, C, and D in the SO, and clade C and D in the PAG, representing a gradual shift from C- to D-dominated coral hosts. The analysis of symbiont diversity in an Operational Taxonomic Unit (OTU)-based framework allowed the identification of differences in symbiont taxon richness over geographical regions and host genera. Main conclusions: Our study represents a comprehensive overview over biogeography and molecular diversity of Symbiodinium in the Arabian Seas, where coral reefs thrive in one of the most extreme environmental settings on the planet. As such our data will serve as a baseline for further exploration into the effects of environmental change on host-symbiont pairings and the identification and ecological significance of Symbiodinium types from regions already experiencing ' Future Ocean' conditions.

The Arabian Sea, notably the Sea of Oman, has exhibited a gradual warming trend since the twentieth century, expected to persist in the future, necessitating a climatological assessment for potential environmental disaster mitigation. This study conducts a comprehensive analysis using satellite-derived data on sea surface temperature (SST), Chlorophyll-a (Chl-a), sea level anomaly (SLA), and wind stress curl (WSC) to understand the region's climate dynamics. Phytoplankton (Chlorophyll-a) in the Sea of Oman plays a vital role in the ocean ecosystem, serving as primary producers and oxygen suppliers by fixing atmospheric carbon dioxide. Over the past four decade, the average Chl-a in the Sea of Oman was 3.06 mg/m 3 , with elevated levels (> 5.5 mg/m 3 ) observed along coastal regions, peaking in summer and declining in winter. Over four decades, SST has risen by 0.658 °C on average, with the highest gradient magnitude observed along the coast. SLA has steadily increased exceeding 0.722 cm over the entire period (1993–2021). WSC shows seasonal variations, with high values (> 1 N/m 2 ) in July and August and slightly lower values in winter. Furthermore, significant correlations between ocean variables and major climatic oscillations such as the Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), El Nino-3.4 (Nino3.4), and the Dipole Mode Index (DMI) are identified, highlighting the intricate interplay shaping the Arabian Sea's ecosystem and providing critical insights for effective environmental management strategies. Implement integrated monitoring and adaptive management strategies to mitigate the impacts of climate variability on the Sea of Oman marine ecosystem.

Current seawater temperatures around the northeastern Arabian Peninsula resemble future global forecasts as temperatures > 35 °C are commonly observed in summer. To provide a more fundamental aim of understanding the structure of wild populations in extreme environmental conditions, we conducted a population genetic study of a widespread, regional endemic table coral species, Acropora downingi, across the northeastern Arabian Peninsula. A total of 63 samples were collected in the southern Arabian/Persian Gulf (Abu Dhabi and Qatar) and the Sea of Oman (northeastern Oman). Using RAD-seq techniques, we described the population structure of A. downingi across the study area. Pairwise G’st and distance-based analyses using neutral markers displayed two distinct genetic clusters: one represented by Arabian/Persian Gulf individuals, and the other by Sea of Oman individuals. Nevertheless, a model-based method applied to the genetic data suggested a panmictic population encompassing both seas. Hypotheses to explain the distinctiveness of phylogeographic subregions in the northeastern Arabian Peninsula rely on either (1) bottleneck events due to successive mass coral bleaching, (2) recent founder effect, (3) ecological speciation due to the large spatial gradients in physical conditions, or (4) the combination of seascape features, ocean circulation and larval traits. Neutral markers indicated a slightly structured population of A. downingi, which exclude the ecological speciation hypothesis. Future studies across a broader range of organisms are required to furnish evidence for existing hypotheses explaining a population structure observed in the study area. Though this is the most thermally tolerant acroporid species worldwide, A. downingi corals in the Arabian/Persian Gulf have undergone major mortality events over the past three decades. Therefore, the present genetic study has important implications for understanding patterns and processes of differentiation in this group, whose populations may be pushed to extinction as the Arabian/Persian Gulf warms.

With the allied invasion, the southern half of Iran became the scene of a large presence of British and American occupation forces. The negative consequences of the styling of foreign elements during all the years of war and even afterward affected these areas in various dimensions of their health. The negative consequences of the occupation of southern Iran, the health and healthcare system of this part of Iran suffered problems in various forms of shortage of medicines, equipment, and treatment staff, especially the spread of various infectious and communicable diseases. The article aims to examine the effects of World War II on the southern, southwestern, and eastern regions of Iran from 1939 to 1945 and its consequences in the spread of infectious diseases in these regions. The research with an analytical-historical method relies on the library method and is based on the study of the data of unpublished documents from the archives of the National Archives and Library Organization, medical and economic social publications, and various local and public newspapers of Iran during this period. The study of documents and publications shows that due to Allied restrictive policies and successive waves of famine and widespread malnutrition, epidemic diseases, and drug monopoly, these areas experienced a period of severe decline in public health and spread of various infectious diseases.

The population dynamics and exploitation ratios of the narrow-barred Spanish mackerel (Scomberomorus commerson, Lacépède, 1800) were investigated from August 2020 to February 2023, with data collected from three landing sites (Bushehr, Bandar Abbas, and Chabahar) of Iran waters. During the study period, only length was measured for 6504 specimens and both the length and weight were measured for 504 specimens. The mean fork length of the samples was 86 ± 20 cm, and the mean weight was 6230 ± 3742 g. The relationship between length and weight for the total samples was described by the equation W = 0.022 × CL2.76 (n = 504, R2 = 0.90, 95% C.I. for b = 2.52–2.91). The population dynamics indices for S. commerson were as follows: infinite length (Linf) = 173 cm, natural mortality (M) = 0.47 per year, growth coefficient (K) = 0.52 per year, total mortality (Z) = 1.42 ± 0.06 (95% C.I. = 1.36–1.48), fishing mortality (F) = 0.95 per year, and exploitation coefficient (E) = 0.67. The exploitation rate (U) and total stock at the beginning of the year (B0) were 0.6 and 48,333 tons, respectively. The annual average standing stock (Bt) was estimated at 30,526 tons. The exploitation ratio for maximum sustainable yield (EMSY) was 0.50, and fishing mortality at maximum sustainable yield (FMSY) was 1.5. The estimated range for maximum sustainable yield (MSY, in 1000 tons), the B/BMSY ratio, F/FMSY ratio, and saturation (S) ratio of S. commerson in the Iranian part of the Persian Gulf and the Sea of Oman was 20 (17–25), 1.55 (1.25–1.73), 0.90 (0.8–1.12), and 0.45, respectively. The stock of S. commerson is approaching overfishing in Iran waters, imposing immediate management actions to reduce catch and fishing effort.

Microbial composition across substrates in mangroves, particularly in the Middle East, remains unclear. This study characterized bacterial communities in sediment, water, Terebralia palustris snail guts, and plastic associated with Avicennia marina mangrove forests in two coastal lagoons in the Sea of Oman using 16S rDNA gene MiSeq sequencing. The genus Vibrio dominated all substrates except water. In the gut of snails, Vibrio is composed of 80–99% of all bacterial genera. The water samples showed a different pattern, with the genus Sunxiuqinia being dominant in both Sawadi (50.80%) and Qurum (49.29%) lagoons. There were significant differences in bacterial communities on different substrata, in particular plastic. Snail guts harbored the highest number of unique Operational Taxonomic Units (OTUs) in both lagoons, accounting for 30.97% OTUs in Sawadi and 28.91% OTUs in Qurum, compared to other substrates. Plastic in the polluted Sawadi lagoon with low salinity harbored distinct genera such as Vibrio, Aestuariibacter, Zunongwangia, and Jeotgalibacillus, which were absent in the Qurum lagoon with higher salinity and lower pollution. Sawadi lagoon exhibited higher species diversity in sediment and plastic substrates, while Qurum lagoon demonstrated lower species diversity. The principal component analysis (PCA) indicates that environmental factors such as salinity, pH, and nutrient levels significantly influence bacterial community composition across substrates. Variations in organic matter and potential anthropogenic influences, particularly from plastics, further shape bacterial communities. This study highlights the complex microbial communities in mangrove ecosystems, emphasizing the importance of considering multiple substrates in mangrove microbial ecology studies. The understanding of microbial dynamics and anthropogenic impacts is crucial for shaping effective conservation and management strategies in mangrove ecosystems, particularly in the face of environmental changes.

Cochlodinium polykrikoides formed large blooms in the coastal waters of Oman from October 2008 through mid-January 2009, and satellite images from Aqua-MODIS and region-wide reports suggest that this bloom was found throughout the Arabian Gulf and Sea of Oman for more than 10 months. The unusual occurrence of this species appears to have supplanted the more regularly occurring bloom species, Noctiluca scintillans, in 2008–2009. For the first 2 weeks of the coastal Omani bloom, C. polykrikoides abundance was near monospecific proportions, with cell densities ranging from 4.6 × 10³ to 9 × 10⁶ cells L⁻¹ and very high levels of chlorophyll a (78.0 μg L⁻¹) were also recorded. The regional progression of the bloom likely began with stronger than normal upwelling along the Iranian and northern Omani coasts during the southwest monsoon in late summer, followed by discharge of unusually warm coastal plume water along the coast of Oman with the reversal of monsoonal winds in late October. The occurrence and persistence of high densities of C. polykrikoides in Oman coastal water were also significantly influenced by an elevated nutrient load and warmer than normal temperatures. Concentrations of nutrients, especially NH₄ ⁺, urea, PO₄ ³⁻, and organic nitrogen and phosphorus, were manyfold higher than observed in the year prior or since. These findings suggest that mesoscale features were important in bloom dynamics more regionally, but locally the bloom was sustained by nutrient enrichment supplemented by its mixotrophic capabilities.

Dissolved oxygen and current observations from a cabled ocean observatory in the Sea of Oman show that the annual recurrence of coastal hypoxia, defined as dissolved oxygen concentrations ≤63 μM, is associated with the seasonal cycle of local monsoon winds. The observations represent the first long-term (5+ years) continuous moored observations off the northern Omani coast. During the summer/fall southwest (SW) monsoon season (Jun-Nov), winds in the Sea of Oman generate ocean currents that result in coastal upwelling of subsurface waters with low dissolved oxygen concentrations. The source of the poorly oxygenated water is the oxygen minimum zone (OMZ) in the Arabian Sea, a layer approximately 1000-m thick within the 100 to 1200 m depth range, where dissolved oxygen values approach anoxia. During the winter monsoon season (Dec-Feb), the Sea of Oman winds are from the northwest, forcing strong and persistent southeast currents. These winds generate oceanic downwelling conditions along the coastal ocean that ventilate waters at depth. Possible impacts of the monsoon-driven seasonal hypoxia on local fisheries and implications due to climate change are also discussed in this study.

The coast of Oman is undergoing huge coastal developments in order to realize Oman Vision 2040, covering all the strategic sectors. Historical data of coastal hydrodynamic parameters is scarce, even though its importance for properly designed coastal structures is recognized. In the present study, Acoustic Doppler Current Profilers (ADCP) were deployed at eleven locations along the coast of Oman. These locations were selected based on their strategic importance for the country. The duration of the deployments were between 60 and 265 days. The measured data of the waves and currents were collected and analyzed using equipment-specific software and Excel. The significant wave heights can reach 2 m along the whole coast of Oman. The southern coast is dominated by swells. The maximum to significant wave height ratio is approximately 1.5, which is less than the value of 2 obtained using the Rayleigh distribution. The coastal currents are stronger along the southern coast than those along the northern coast. The range of current magnitude is between 0.02 m/s and 0.8 m/s. This baseline study will help the public authorities in establishing permanent hydrodynamic measurement stations along the coast of Oman. Moreover, these measurements will serve the practicing engineers in designing coastal structures along the coast of Oman.

Although several researchers have examined otoliths of marine fishes from the Persian Gulf and the Gulf of Oman, none has reported abnormalities. A recent effort to identify stocks of marine fishes of the Persian Gulf and the Gulf of Oman revealed that several species have abnormal otoliths. This is the first study reporting and describing the occurrence of abnormal otoliths from the fishes collected from the Persian Gulf and the Gulf of Oman. A total of 225 fish specimens belong to 83 species and 33 families were randomly sampled from the Persian Gulf and the Gulf of Oman. The standard lengths (SL) were measured to the nearest 0.5 mm. The otoliths were extracted, cleaned, and described following available literature. The specimens and their otoliths were deposited in the Zoological Museum at Shahid Bahonar University of Kerman (ZM-SBUK). Among the studied 83 species, we found six species having abnormal otoliths (4.8% of the studied specimens). They belong to six families; Carangidae, Chanidae, Chirocentridae, Leiognathidae, Paralichthyidae, and Sparidae. The number of specimens with abnormal otoliths only in one side (either right or left side) was six, and those with abnormal otoliths in both sides was five. The left otoliths presented more extreme changes than the right. The observed abnormalities can be classified into three types; asteriscus attached to sagittal (the most common); otoliths with a more translucent or crystalline appearance in surface or outlines; and those with an abnormality in their sulcus region. Ecologically, the Persian Gulf is an environment having various kinds of stresses such as salinity fluctuation, acidification, and the water temperature. Such stressors probably affect otolith formation during the larval stages of these fishes and are responsible for the observed abnormalities.