Gulf Of Oman Research Articles

Radiological Risk to Human and Non-Human Biota Due to Radioactivity in Coastal Sand and Marine Sediments, Gulf of Oman.

Natural and 137Cs radioactivity in coastal marine sediment samples was measured using gamma spectrometry. Samples were collected at 16 locations from four beaches along the coastal area of Muscat City, Gulf of Oman. Radioactivity in beach sand was used to estimate the radiological risk parameters to humans, whereas the radioactivity in marine sediments was used to assess the radiological risk parameters to non-human biota, using the ERICA Tool. The average radioactivity concentrations (Bqkg−1) of 226Ra, 232Th, 40K, 210Pb and 137Cs in sediments (sand) were as follows: 16.2 (16.3), 34.5(27.8), 54.7 (45.6), 46.8 (44.9) and 0.08 (0.10), respectively. In sand samples, the estimated average indoor () and outdoor () air absorbed dose rates due to natural radioactivity were 49.26 and 27.4 and the total effective dose (; µSvy−1) ranged from 150.2 to 498.9 (average: 275.2). The measured radioactivity resulted in an excess lifetime cancer risk (ELCR) in the range of 58–203 (average: 111) in and an average gonadal dose (AGD; µGy.y−1) ranged from 97.3 to 329.5 (average: 181.1). Total dose rate per marine organism ranged from 0.035 µGy h−1 (in zooplankton) to 0.564 µGy h−1 (in phytoplankton). The results showed marine sediments as an important source of radiation exposure to biota in the aquatic environment. Regular monitoring of radioactivity levels is vital for radiation risk confinement. The results provide an important radiological risk profile parameter to which future radioactivity levels in marine environments can be compared.

Crustal and Mantle Deformation Inherited From Obduction of the Semail Ophiolite (Oman) and Continental Collision (Zagros)

AbstractA common deviation from typical subduction models occurs when thrust sheets of oceanic crust and upper‐mantle rocks are emplaced over more buoyant continental lithosphere. The archetypal example of ophiolite obduction is the Semail ophiolite in the United Arab Emirates (UAE)‐Oman orogenic belt, formed and obducted onto the Arabian continental margin during the Late Cretaceous. The Strait of Hormuz syntaxis, the northern extent of the UAE‐Oman mountains, marks the transition from ocean‐continent convergence in the Gulf of Oman to continental collision along the Zagros Mountains. Based on new seismic data from a focused recording network, we infer continental crustal and mantle deformation in the northeastern corner of the Arabian plate (including the southern Zagros and the UAE‐Oman mountains), using observations from anisotropic tomography and shear‐wave splitting (SWS) measurements. We recover a change of ∼90° (from approximately WNW to nearly NS) in the axis of fast‐anisotropic orientations in the crust from the Zagros to the UAE‐Oman mountain belt, consistent with the dominant strike of the orogenic belts. We also find evidence in our SWS parameters for localized fossil deformation in the lithospheric mantle underlying the UAE‐Oman mountain range, possibly related to stress‐induced tectonism triggered by north‐east oriented underthrusting of the proto‐Arabian continental margin beneath the overriding Semail ophiolite. Shear‐wave‐splitting anisotropy orientations along two transects across the northern Musandam peninsula, averaging 15° anticlockwise from the north, provide the first geophysical verification of previous geological evidence that suggests a NE polarity of the Late Cretaceous Oman subduction zone system.

Monthly variations of total lipids content and some biological parameters of rock oyster (Saccostrea cucullata) in the Northern coasts of the Gulf of Oman

The present study was conducted to assess the monthly variations of total lipids content and some biological parameters of rock oyster in the Northern coasts of the Gulf of Oman (Iranian coast) from October 2017 until March 2018 in relation to environm ental conditions. According to the results, the maximum and minimum lengths were recorded in December and February, respectively. The highest amounts of weight, dry and wet weight, and condition index were recorded in autumn. There was also a significant difference between the months and the regions for these parameters ( p < 0.05). The highest amount of total lipids was observed in March (3.1±1.84) with a significant difference relative to October and November and the lowest amount one was observed in October (2.15±1.6). Also, there was a significant relationship between the total lipids and the temperature. Moreover, there were higher amounts of total lipids in Saccostrea cucullata in winter compared to those in autumn. In general, one of the reasons for the differences in length, weight and total lipids at different stations over different months can mainly be explained by the reproduction season, nutritional conditions, and environmental factors such as temperature and salinity.

Intraseasonal Sea Level Variability in the Persian Gulf

AbstractSatellite observations are used to establish the dominant magnitudes, scales, and mechanisms of intraseasonal variability in ocean dynamic sea level (ζ) in the Persian Gulf over 2002–15. Empirical orthogonal function (EOF) analysis applied to altimetry data reveals a basinwide, single-signed intraseasonal fluctuation that contributes importantly to ζ variance in the Persian Gulf at monthly to decadal time scales. An EOF analysis of Gravity Recovery and Climate Experiment (GRACE) observations over the same period returns a similar large-scale mode of intraseasonal variability, suggesting that the basinwide intraseasonal ζ variation has a predominantly barotropic nature. A linear barotropic theory is developed to interpret the data. The theory represents Persian Gulf average ζ () in terms of local freshwater flux, barometric pressure, and wind stress forcing, as well as ζ at the boundary in the Gulf of Oman. The theory is tested using a multiple linear regression with these freshwater flux, barometric pressure, wind stress, and boundary ζ quantities as input and as output. The regression explains 70% ± 9% (95% confidence interval) of the intraseasonal variance. Numerical values of regression coefficients computed empirically from the data are consistent with theoretical expectations from first principles. Results point to a substantial nonisostatic response to surface loading. The Gulf of Oman ζ boundary condition shows lagged correlation with ζ upstream along the Indian subcontinent, Maritime Continent, and equatorial Indian Ocean, suggesting a large-scale Indian Ocean influence on intraseasonal variation mediated by coastal and equatorial waves and hinting at potential predictability. This study highlights the value of GRACE for understanding sea level in an understudied marginal sea.

WITHDRAWN: Sea Cucumbers of the Arabian Peninsula and Iran - a review of historical and current research trends

Sea cucumbers are benthic marine invertebrates with immense ecological and commercial value. Processed sea cucumbers known as "Beche-de-mer" are a delicacy in southeast Asian countries with an ever-increasing demand depleting wild stocks on a global scale. Aquaculture techniques are well developed for commercially important species (eg. Holothuria scabra) to aid in conservation and trade. In the Arabian Peninsula and Iran, where the major land mass is surrounded by marginal seas (Arabian/Persian Gulf, Gulf of Oman, Arabian Sea, Gulf of Aden, and Red Sea), studies on sea cucumbers are rather limited and its economic value is underestimated. Historical and current research trends indicate impoverished diversity (82 species) due to environmental extremes. Artisanal fisheries exist for the sea cucumbers of Iran, Oman, and Saudi Arabia, with Yemen and United Arab Emirates (UAE) playing a key role in collection and export to Asian countries. Stock assessment and data on export indicates depletion of natural stocks in Saudi Arabia and Oman. Aquaculture trials of high value species (H. scabra) were successful in Saudi Arabia, Oman and Iran with prospects for further expansion. Research on ecotoxicological properties and bioactive substances conducted in Iran demonstrates an immense research potential. Molecular phylogeny, biology, use in bioremediation, and characterisation of bioactive compounds were identified as potential gaps in research. Expanding aquaculture operations could revive exports and recuperate damaged stocks through sea ranching. Furthermore, regional cooperation, networking, training, and capacity building could help fill the gaps in sea cucumber research, which will aid in its effective conservation and management.

Multi-peaked directional wave spectra based on extensive field measurement data in the Gulf of Oman

Multi-peaked directional wave spectra have been estimated by the well-known maximum likelihood method and modeled by applying a numerical optimization approach that uses a gradient OQNLP algorithm. The research is based on field measurement data from a 210-km-long area at the northern coasts of the Gulf of Oman. This modeling approach allows the fitting of various spectral models. Accordingly, three directional spectrum models with combinations of frequency and directional spreading functions have been evaluated and proper models for directional waves have been presented. On the other hand, the introduced optimization algorithm is modified by adding a constraint to zeroth-order spectral moment (m0) value to improve the fitting accuracy in the frequency spectrum. It has been shown that selecting the appropriate model for each of the frequency and directional functions can significantly improve the performance of both. Among the evaluated directional models, the accuracy of the results based on both JONSWAP Sech2 and Gamma Sech2 models was about 25% better in the frequency domain and about 10% better in the full directional domain than JONSWAP Cos2s model. Besides, in most of the observed swell components, because of their wide spectrums with low peak values, the use of the Gamma frequency model performs better than the JONSWAP model.

Feasibility study of a hybrid grid‐tied photovoltaic‐wave system on the shores of Persian Gulf

AbstractThe application of hybrid renewable energy systems (HRES) has been gaining ground in the recent years due to low‐carbon policies of nations and increasing energy demand. However, marine energy sources such as waves have remained untapped notwithstanding their significant potential particularly in Iran. Iran has significant wave and energy resources, which can be exploited to overcome the energy crisis in the country. In this regard, this research examines the feasibility of a 15 kW hybrid wave‐photovoltaic system in three ports of Iran namely Chabahar, Bushehr and Bandar Abbas on the shores of Persian Gulf and Oman Gulf using MATLAB/Simulink. Oscillating water column converters are deployed to harvest the wave energy. The findings indicated that the maximum energy production occurs in April for Chabahar and Bandar Abbas, and in July for Bushehr, while the minimum is in December for all the locations under study. The annual energy generation reaches 524, 506 and 520 kWh in Chabahar, Bandar Abbas and Bushehr, respectively. The levelized cost of electricity was estimated at 128 $/kWh for Bandar Abbas, 125 $/kWh for Bushehr and 124 $/kWh for Chabahar, indicating that Chabahar is the optimal location for the installation of the proposed system.

Dynamics of Dipsastraea pallida-symbiont association following bleaching events across the northern Persian Gulf and Gulf of Oman

Reef-building corals are in obligate symbiosis with dinoflagellates of the family Symbiodiniaceae. The partnership, however, is prone to breakdown as a result of thermal stress, which leads to coral bleaching. According to the Adaptive Bleaching Hypothesis, corals’ recovery from bleaching is profoundly influenced by forming stable associations with thermotolerant algal strains during bleaching. Consequently, the knowledge of the diversity of host-symbiont associations during this period is substantial. Since the extent of symbiont shuffling varies among different host taxa, we investigated the diversity of dominant Symbiodiniaceae in association with the scleractinian coral Dipsastraea pallida before and after massive bleaching events of 2017 in the Persian Gulf and 2018 in the Gulf of Oman. We observed a flexible association between D. pallida and five lineages of Symbiodiniaceae (i.e., ITS2-types A1.4, C3, C39, D1a, D5) with a clear regional pattern. However, the pattern of these associations was changed following bleaching events, with the complete replacement of Cladocopium-C39 by Durusdinium-D1a in the Gulf of Oman, and increased proportion of Durusdinium-D1a and disappearance of Symbiodinium-A1.4 in the northeastern Persian Gulf. In the westernmost Persian Gulf, on the other hand, a stable D. pallida-Cladocopium-C3 partnership was observed. These findings convey the potential of D. pallida to shift the prevalence of its symbiont communities within a population in response to bleaching, which may reflect symbiont shuffling and/or differential mortality and partly explain the predominance of Dipsastraea corals in the Persian Gulf and Gulf of Oman.

Stock differentiation of the greater lizardfish Saurida tumbil (Teleostei: Synodontidae) collected along the western coast of the Arabian Gulf and Sea of Oman using meristic characters.

Meristic variation among stocks of greater lizardfish Saurida tumbil through the western coasts of the Arabian Gulf and Sea of Oman was examined using meristic characters. Statistical analysis of meristic traits proposed that there is constrained migration of populations of greater lizardfish along the western coast of the Arabian Gulf and Sea of Oman. Overlapping of the two samples from the northern part of the Arabian Gulf (Iraq-Kuwait waters), three samples from the middle region of the Arabian Gulf (Bahrain-Qatar-Saudi Arabia) and two samples from the southern part of the Arabian Gulf/Sea of Oman (United Arab Emirates-Sultanate of Oman) suggested that there are three self-recruiting populations in the studied area. Inspection of the role of each meristic trait variable to Canonical discriminant analysis showed that changes among samples appeared to be linked with the pattern of distribution of water temperature and configuration of current in both the Arabian Gulf and Sea of Oman areas.

An updated checklist of marine gastropods of the Persian Gulf and Gulf of Oman.

Here we review and evaluate the marine gastropods of the Persian Gulf and Gulf of Oman based on published accounts. A total of 850 species belonging to 129 families have records in the Persian Gulf (585) and Gulf of Oman (648), of which 383 species occurred in both regions. We updated the taxonomy and deleted records with dubious identifications. The resultant checklist documents the currently known diversity of marine gastropods from the Persian Gulf and Gulf of Oman and provides a foundation for future studies of the biodiversity of these areas.

Spreading and Vertical Structure of the Persian Gulf and Red Sea Outflows in the Northwestern Indian Ocean

AbstractIn the Indian Ocean, salty water masses from the Persian Gulf and Red Sea are important sources of salt, heat, and nutrients. Across the Arabian Sea, these outflows impact human and biological activities, their thermohaline characteristics and shapes exhibiting important spatial and seasonal variability. The knowledge of the water masses properties is important to validate realistic simulations of the Indian Ocean. A classical approach to study these water masses is to track them on specific isopycnal levels. Nevertheless, their peaking thermohaline characteristics are not always found at a specific density but rather spread over a range. Here, we develop a detection algorithm able to capture the full vertical structure of the outflows, that we applied to a data set of about 126,000 vertical profiles. We are thus able to quantify the changes in their thermohaline signatures and in their vertical structures, characterized here by the intensity of the salinity peaks of the water masses and lateral injection of fresh and salty waters, and describe their spatial variability. Across the northwestern Indian Ocean, the salty outflows undergo several changes, diminishing their thermohaline signatures and peaks and layering. In their early stages in the narrow Gulf of Oman and Aden, the outflows present configurations indicative of diapycnal mixing. In the same regions and along the western edge of the Arabian Sea, these water masses are subject to lateral mixing. All over the Arabian Sea, salt fingering conditions are met for lower layers of the outflows.

Analysis of Ashobaa tropical cyclone-induced waves in the Northern Indian Ocean using coupled atmosphere–wave modeling

The Tropical Cyclones play a significant role in the world natural disasters. At the time of the cyclones, the atmosphere and the ocean are constantly exchanging energy. In this study, spectral and statistical analyses of the waves affected by the Cyclone Ashobaa in the northern Indian Ocean were investigated. For this purpose, a Coupled Atmosphere–Wave model as a subsystem of COAWST (Coupled Ocean–Atmosphere–Wave–Sediment Transport) was employed. In this modeling system, the Weather Research and Forecasting model (WRF) and the Simulating Waves Near-Shore model (SWAN), were used. Four monitoring points were considered to analyze the waves in the northern Indian Ocean in the offshores of Mumbai, Karachi, Chabahar and Muscat. The results of wave simulation showed that, the wave height on the northeastern offshore of the Arabian Sea is higher than the wave height on the offshore of the Gulf of Oman. As a result, the east and northeast coasts of the Arabian Sea are mostly affected than the coasts of the Gulf of Oman by the Cyclone Ashobaa-induced storm surges and swells.

Diversity of intertidal, epibiotic, and fouling barnacles (Cirripedia, Thoracica) from Gujarat, northwest India.

The present work studied the diversity of intertidal, epibiotic, and fouling barnacles in the state of Gujarat, northwest India. In total, eleven species belonging to eight genera and five families were recorded in the present study. The Arabian intertidal species Tetraclita ehsani Shahdadi, Chan & Sari, 2011 and Chthamalus barnesi Achituv & Safriel, 1980 are common in the high- and mid-intertidal rocky shores of Gujarat suggesting that the Gujarat barnacle assemblages are similar to the assemblages in the Gulf of Oman Ecoregion. The biogeographical boundary between the Gulf of Oman and Western Indian ecoregions for barnacles should probably extend southward towards the waters adjacent to Mumbai, where Indo-Pacific species of intertidal barnacles dominate. This study provides the first reports of the common widely distributed balanomorph barnacles Striatobalanus tenuis (Hoek, 1883), Tetraclitella karandei Ross, 1971, Amphibalanus reticulatus (Utinomi, 1967), and lepadid barnacle Lepas anatifera Linnaeus, 1758 in Gujarat, as well as of the chthamalid barnacle Chthamalus barnesi in India.

Skeletal lesion assessment of a Neolithic fishing community: Osteological data from Area 43 of Ra’s al Hamra 5, Oman

We assess the state of health of individuals recovered from the Neolithic fishing community of Ra’s al Hamra 5 (RH5). The archaeological site is located by the Oman gulf on the Arabian Seacoast near the suburb of Qurum; located near the Omani capital city Muscat. The graveyard dates from 3800 BCE to 3300 BCE. We recorded lesions specific to degenerative joint disease, vertebral osteoarthritis, periostitis, dental and oral defects, and cranial pitting from Area 43 of the graveyard. Lesions are scored simply as presence or absence. Intra-site (Area 43) comparison is done by age groupings (sub-adult and adult). Comparison is also made between the findings of dietary lesions, oral defects and DJD from the 77 burials from Area 43 and 182 non-Area 43 burials of the RH5 site. No differences in these lesion frequencies are found between the two parts of the RH5 graveyard. Critically, we found that most of the sub-adults in Area 43 lacked skeletal indicators of illness, suggesting acute origins for their untimely deaths. A comparison is also made with other Neolithic sites for example, a comparison with the contemporary pastoral community of Jebel al-Buhais 18 revealed no statistically significant differences in most skeletal lesion frequencies, except for DJD, antemortem tooth loss and osteoarthritis. A comparison with several Neolithic farming communities instead documented statistically higher rates of lesions compared to the RH5 fishing community. Both comparisons suggest that a fishing economic strategy provided the RH5 inhabitants with an adequate diet and less stressors than other Neolithic economic strategies.

DISTRIBUTION OF INVASIVE SPECIES <i>PROSOPIS JULIFLORA</i> (MIMOSACEAE) IN FUJAIRA (UAE)

The article analyzes the secondary area in the Emirate of Fujairah, as well as the peculiarities of seed dispersing, seed germination and early seedling development of Mesquite, or Prosopis juliflora - the alien species of Mimosaceae, which appeared on the territory of the Emirates in the twentieth century, and one of the first collected herbarium specimen is dated 1983. In the secondary area most often, the Mesquite is found in anthropogenic habitats: in gardens, as well as near roads, on waste grounds, less frequent on the streets of settlements, garden fences etc. In regions represented by herbarium collections, P. juliflora is successfully naturalized and creates stable self-sustaining populations. It has a complex of specific helio-mesomorphic features that allow it to take root successfully in relatively open moderately wet, and even dry or saline habitats and compete with native species of acacia ( Acacia tortilis, A. ehrenbergii ) and local prosopis ( P. cineraria ). Characteristics such as good germination, significant morphological, dimensional and temporal variability of premature individuals of P. juliflora , identified in this work, undoubtedly contribute to the successful naturalization of the species in the secondary range and its wide distribution throughout the Emirate. Due to the high aggressiveness of Mesquite, it is necessary to develop a method of dealing with this plant in the UAE, which will stop its uncontrolled settlement in the region. We have compiled a map of Mesquite distribution in Fujairah and surrounding areas, which clearly shows the scale of the disaster. A method for assessing invasion on a five-level scale based on reproductive success has been developed and applied. The structure of ecotopes at an early and middle stage of penetration of P. juliflora was analyzed using large wastelands (2 and 1.2 ha) in the village Mirbah and the city of Fujairah on the coast of the Gulf of Oman.

Population differentiation in the Persian Gulf and Gulf of Oman: insights from the ghost shrimp's associated copepods, Clausidium iranensis and Clausidium persiaensis

AbstractEvolution and population genetic structure of marine species across the Persian Gulf and Gulf of Oman are shaped by two complex factors: the geological history and the present pattern of marine currents. Characterizing and comparing the genetic structures of co-existing species, such as host–parasite associations, allow the discrimination of the relative importance of environmental factors and life history traits that influenced gene flow and demographic events. In this study, we compare two associated Clausidium copepod species (C. persiaensis Sepahvand & Kihara 2017 and C. iranensis Sepahvand, Kihara & Boxshall 2019) along the south coast of Iran in two geological settings. We analysed partial nucleotide sequences of the mtCOI gene using divergence estimates (FST) and haplotype networks to infer intraspecific population connectivity in the two Gulfs. The results obtained demonstrate the existence of two genetically and geographically distinct clades, corresponding to the Persian Gulf and Gulf of Oman populations. Our results also indicate high diversity, population expansion and high connectivity among populations of C. persiaensis and C. iranensis in the Persian Gulf and Gulf of Oman.

Catch Per Unit Area (CPUA) estimation and distribution pattern of pharaoh cuttlefish from North Coast of Gulf of Oman

Catch Per Unit Area (CPUA) estimation and distribution pattern of pharaoh cuttlefish from North Coast of Gulf of Oman

Observation of infragravity wave processes near the coastal cliffs of Chabahar (Gulf of Oman)

This study analyzed the characteristics of infragravity waves (hereafter IGWs) based on field observations collected near the plunging cliffs of Chabahar bay, Iran. Observations were made near Chabahar city during the summer monsoon season of 2018. The wave climate included two different durations of sea and swell predominance, with a maximum wave height reaching 2.5 m. Concurrent with the duration of the sea predominance, the ratio of IGW to swell wave height had an insensitive fluctuation against tidal variations, while this ratio had a strong negative correlation with tidal level during the high swell condition. The investigation of directional wave energy distribution revealed two correlated trends of shoreward and seaward IGWs with the wave regime.Larger values of the IGW reflection coefficients were observed during high sea wave conditions compared with high swell conditions. The IGW reflection coefficients decreased against swell energy growth with a logarithmic trend. The bound IGW energy fraction was studied using bispectral analysis. It is demonstrated that the maximum values of this parameter corresponded to high swell waves observed within low ebbs of the spring tide. The insignificant values of bound IGW energy fraction and the non-extended surf-zone revealed that most of the released IGWs originated from offshore and intermediate water depths. In addition, it was revealed that the inverse tidal trend of normalized IGW by swell height was due to bound IGW enhancement during ebb periods as a result of the nonlinear coupling of swell waves.

Stable isotope ratios (δ13C and δ15N) and heavy metal levels in macroalgae, sediment, and benthos from the northern parts of Persian Gulf and the Gulf of Oman

In this investigation, δ13C and δ15N isotope ratios and heavy metal levels were assessed in macroalgae, sediment samples, and benthic species from northern parts of the Persian Gulf and the Gulf of Oman. The highest δ15N values in algal samples (11±0.42), indicative of anthropogenic organic N inputs, were detected in the Sadaf region, whereas the lowest values (3.17 ± 0.12), indicative of anthropogenic inorganic inputs, were detected in the Parvaz region. In addition to sediment quality guidelines (SQGs), contamination factors (CF), enrichment factors (EF), contamination degree (CD), pollution load index (PLI), geo accumulation index (Igeo), and potential ecological risk index (RI) were employed to assess the anthropogenic influence on sediment quality and to describe the sensitivity of the biota to toxic heavy metals. The obtained results demonstrate that the analyzed elements (Mn, Cr, Ni, Pb, Zn, Cu, Co, and V) had no ecological risk in the sampling area.

Molecular phylogeny and taxonomy of the genus Pilumnus Leach, 1815 (Eucrustacea: Brachyura: Pilumnidae) in the Persian Gulf and Gulf of Oman

The genus Pilumnus covering a large group of bristle crabs, a typical resident of rocky, cobble and coral habitats. Taxonomy of the genus in the Persian Gulf and Gulf of Oman have always been source of disagreement among specialists due to potential taxonomic uncertainty in the genus. We used combined morphological and molecular characteristics to provide an insight into the real diversity within this genus. Partial fragment of two mitochondrial genes (COI and 16S rRNA) and one nuclear gene (H3) were used for molecular analyses. Both Bayesian and Maximum likelihood methods estimated a similar tree topology with highly supported clades. The tree showed the occurrence of two groups including the Atlantic and Indo-West Pacific species. Our result showed that there is a well consistency between morphological and molecular characteristics at interspecific level. Five species were identified from the Persian Gulf and Gulf of Oman, including P. incanus, P. longicornis, P. savignyi, P. persicus n. sp. and P. parvusi n. sp. Pilumnus persicus n. sp. is closely related to P. minutus, which has been already recorded from the region, but it is described here as a new species; according to current morphology and molecular data. Pilumnus parvusi n. sp. differed from the other congeners occurring in the Persian Gulf, whereas it is genetically presented as sister clade to the Atlantic species group.