Concentrations of heavy metals, namely, cadmium, copper, zinc, lead, and chromium were measured in the muscle tissue of Scomberoides commersonnianus and Cynoglossus arel from the northern waters of the Oman Sea. Human health risk assessment for Iranian child and adult consumers were also evaluated. The mean concentration of zinc and copper were lower than international standards of maximum permissible limits (MPL). The estimated daily and weekly intakes (EDI and EWI) of all metals were lower than permissible tolerable daily intake (PTDI). The permissible frequency of fish consumption (CRmm) of S. commersonnianus and C. arel showed that they are safe for both children and adults even at a high meal frequency (>16 meals/month). Target hazard quotient (THQ) and risk index (HI) values were higher than 1 for Cu in adults, Cu and Zn in children with consumption rate of 7 times per week. Therefore, consumption of these spices of Oman Sea more than 7 times per week can threaten the health of consumers.

For the first time, this study explored the dominant features of Marine HeatWaves (MHWs) in the Persian Gulf and Oman Sea (1982–2020). The spatial extent of MHWs has nearly doubled in the last 24 years. Since 1997, the average number of MHW days in the central parts of the Persian Gulf has increased about 19 times compared to the period 1982–1997. The average number of the detected MHW events has increased by about three times. Simultaneously with the increase in MHWs frequency trend, the trend in the average number of MHW days has also increased. Since 1997, the average number of MHW days in the study area has almost increased by 10 times. The mean duration of the detected MHWs ranged from 5 to10 days. On average, in a major part of the Persian Gulf, about 1–2 MHW events occur annually.

Selected blood biochemical parameters (Glutathione S transferase: GST; Alanine aminotransferase: ALT; Aspartate aminotransferase: AST; Lactate dehydrogenase: LD and glucose) and polycyclic aromatic hydrocarbons (PAHs) were measured in blood samples from 18 green sea turtles (Chelonia mydas) from the Iranian coastline on the northern shore of the Sea of Oman. Mean total PAH concentration in the blood samples was 17.802 ± 1.006 ng/gdw. The study found no significant correlation between blood biochemical parameters and PAHs (p > 0.01), however significant correlations were found between total PAHs and GST activity (p < 0.01). The GST activity measured in this study was useful as a first investigation into the biological effects of PAH pollution as well as in determining the bioavailability of pollution. The results suggest that PAHs might be a factor influencing a reduction in green sea turtle egg fertilization and hatching success. Further study is needed concerning the effects of PAHs and other pollutants on green sea turtles, and specifically on the potential impact on the fetal development of green sea turtles.

This study aimed to investigate the concentration of Cd, Ni, Cr, Pb and As in the tissues of Otolithes ruber and surface sediments in the Oman Sea. Trace element concentrations were analyzed by flame atomic absorption spectrophotometer (FAAS) for ecological and health risk assessment. The results showed a significant difference in trace element concentrations of the liver, muscle and sediments between different stations (p < 0.05). Potential ecological risk index (PER) indicated very high risk for Cd at all stations. Estimated daily intake (EDI) for consumption of Otolithes ruber for Cr, Pb and As was lower than tolerable daily intake (TDI). The mean target hazard quotient (THQ) of Cd and Ni were higher than 1 at all stations. Target cancer risk (TR) for Ni and As were higher than the acceptable value range at all stations. Accordingly, the risk of cancer due to the long-term consumption of this fish can be concerned.

Water and sediment samples were collected from northern coast of Oman Sea covering from Goatr to Hormoz canyon seaport. Water and sediment quality assessment for naturally or anthropogenic radionuclides at Oman Sea as a main strategic golf for trade and transit, is an important issue. Correspondence analysis (CA) by R-mode analysis represents that sigma(T)-temperature-conductivity-O2 parameters are well-correlated with 226Ra, 232Th and 40K. Accordingly Q-mode analysis revealed an indicator samples of ST13W for different radionuclides, ST03W for O2, and simultaneously ST34W-ST21W-ST08W-ST04W for sigma(T) parameters. The CA results overlapped with factor and cluster analysis results that explained 85.8% of total variance of water samples. Descriptive analysis of sediments indicates more significant variation than water samples. The 232Th and 226Ra generally showing that ST13D to ST25D sediments that restricted to Pi Bashk coastline are concentrated from 137Cs and 40K. By comparison with reference-values from Iran and other parts of the world, they are acceptable with respect to environmental and radioisotope hazards.

In the last decade, green Noctiluca scintillans with its symbiont and other dinoflagellates such as Cochlodinium polykrikoides, Prorocentrum micans and Scrippsiella trochoidea have become the dominant HABs, partially replacing the previously dominant diatoms and red Noctiluca scintillans, especially during the northeast monsoon. Fish kills in the Sea of Oman are linked to a slow seasonal decline in oxygen concentration from January to November, probably due to the decomposition of a series of algal blooms and the deep, low oxygen waters periodically impinging the Omani shelf. In the western Arabian Sea, cyclonic eddies upwell low oxygen, nutrient-rich water and the subsequent algal bloom decays and lowers the oxygen further and leads to fish kills. Warming of the surface waters by 1.2°C over the last 5 decades has increased stratification and resulted in a shoaling of the oxycline. This has increased the probability and frequency of upwelling low oxygen water and subsequent fish kills.

Marked shifts in the composition of coral assemblages are occurring at many locations, but it is unknown whether these are permanent shifts reinforced by patterns of population replenishment. This study examined the composition of juvenile coral assemblages across the United Arab Emirates (UAE). Densities of juvenile corals varied significantly among locations, but were highest where coral cover was highest. Juvenile coral assemblages within the Persian Gulf were dominated by Porites, while no Acropora were recorded. We expect therefore, continued declines in Acropora abundance, while observed dominance of Porites is likely to persist. In the Oman Sea, Pocillopora was the dominant juvenile coral, with Acropora and Stylophora also recorded. This study shows that taxonomic differences in replenishment are reinforcing temporal shifts in coral composition within the southern Persian Gulf, but not in the Oman Sea. Differences in environmental conditions and disturbance regimes likely explain the divergent responses between regions.

Oman contains diverse and abundant reef coral communities that extend along a coast that borders three environmentally distinct water bodies, with corals existing under unique and often stressful environmental conditions. In recent years Oman's reefs have undergone considerable change due to recurrent predatory starfish outbreaks, cyclone damage, harmful algal blooms, and other stressors. In this review we summarize current knowledge of the biology and status of corals in Oman, particularly in light of recent stressors and projected future threats, and examine current reef management practices. Oman's coral communities occur in marginal environmental conditions for reefs, and hence are quite vulnerable to anthropogenic effects. We recommend a focus on developing conservation-oriented coral research to guide proactive management and expansion of the number and size of designated protected areas in Oman, particularly those associated with critical coral habitat.

Determining how coral ecosystems are structured within extreme environments may provide insights into how coral reefs are impacted by future climate change. Benthic community structure was examined within the Persian Gulf, and adjacent Musandam and northern Oman regions across a 3-year period (2008–2011) in which all regions were exposed to major disturbances. Although there was evidence of temporal switching in coral composition within regions, communities predominantly reflected local environmental conditions and the disturbance history of each region. Gulf reefs showed little change in coral composition, being dominated by stress-tolerant Faviidae and Poritidae across the 3years. In comparison, Musandam and Oman coral communities were comprised of stress-sensitive Acroporidae and Pocilloporidae; Oman communities showed substantial declines in such taxa and increased cover of stress-tolerant communities. Our results suggest that coral communities may persist within an increasingly disturbed future environment, albeit in a much more structurally simple configuration.

A 3-D prognostic baroclinic hydrodynamic model of the Arabian Gulf (AG) was developed using Delft3D-FLOW. The model was forced with long-term time averaged climatological data over the computational domain and long-term salinity and temperature boundary conditions applied at its tidal open boundary. The model simulation results were thoroughly validated against measured tides from 5 stations and measured currents at 4 locations in the central and southern parts. Water salinity and temperature were validated in space and time using observations spanning over 73years from 1923 to 1996 for the AG, the Strait of Hormuz and the Gulf of Oman. The bottom flow of the AG basin at the vicinity of the Strait of Hormuz was also validated against the available measurements. Seasonal evaporation and surface density spatial distribution maps were produced and compared with available records. The developed model setup successfully generated the AG seasonal stratification and hydrographic conditions.