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Aims: Histopathological study is one of the most appropriate ways to evaluate the effects of contaminants in aquatic organisms. The aim of this study was to evaluate the histopathological changes and histopathological alternation index (HAI) in liver tissue of Pomadasys kaakan and Lutjanus johnii in the Oman Sea.
Materials & Methods: In this study, 18 number Pomadasys kaakan and Lutjanus johnii were captured from there stations Ramin, Konarak and Haft Tir by gillnet in winter 2016. In order to study the type and severity of tissue lesions, liver tissue of both fish species were performed fixation stages in Bowen's solution, tissue processing in tissue processing device, paraffin impression, tissue sections 4-5 microns thickness with microtome, stained with hematoxylin and eosin.
Findings: Tissue lesions observed in fish livers included hepatocyte vacuolization, enlargement of sinusoid, adipose cell accumulation, blood congestion, nuclear pyknosis, hemorrhage and necrosis. Tissue lesions observed in the liver of both fish species were higher in Haft-Tir station and lower in Ramin station than in other stations. Histopathological alternation index in liver tissue of both fish species were higher in Haft-tire station than in the other two stations.
Conclusion: Due to the high traffic of the Haf-Tir dock and its close proximity to other docks in the area, the accumulation of pollutants at this station is more and to cause more severe tissue lesions in fish.
 

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Primary production is a key indicator in the evalution of aquatic ecosystems that can directly affect carbon sequestration. Due to climate change and environmental dynamics, this component has changed spatially and temporally in different ecosystems. Therefore, to understand and monitor these changes, the most important influential parameters include; sea surface temperature, chlorophyll-a and algal bloom on this component and their changes were analyzed based on the time series. Images related to Chl-a, SST and NPP from January 2003 to December 2018 were used by MODIS sensor and VGPM model to estimate NPP in the study area. Aftar pre-processing and extracting the time series algorithm, the trend of variation was determined using the mann-kendall and theil-sen procedure. Then, using enhancing false color composite, algal blooms in the Persian Gulf and the sea of Oman were identified and the amount of chl-a concentration in the algal bloom area and outside the area was determined.  The results of trend analysis with theil-sen procedure showed that the rate of change for chl-a is decreasing in all regions except the fifth region. The highest amount was observed in the fifth region (-0.19), which corresponded to the rate of NPP. The results also show that the highest amount of NPP in the first region in March and the lowest in June and July (540 and 690 gC/m²/day), which corresponds to the amount of chl-a concentration. Despite the apparent correlation, there is no cause-and-effect relationship between SST and chl-a as well as chl-a and NPP. In this way, factors other than chl-a can be considered for algal bloom and NPP.

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Aims: The aim of this study was to investigate the rate of changes in liver enzymes in the plasma of Epinephelus stoliczkae under the exposure of different concentrations of potassium dichromate during 21days in vitro.
Materials & Methods:200 pieces of Epinephelus stoliczkae with average total length 29.6±2.2cm and average total weight389.5±92.4g were caught from the Oman Sea. Three treatments of 3.6, 7.31 and 14.6mg/L chromium(three replications and one control) were selected to sub-lethal toxicity test. The fish were exposed to chromium for 21 days and at 0.5, 1, 7, 14 and 21 days after the start of the experiment to measure the levels of liver enzymes aspartate aminotransferase(AST), alanine aminotransferase(ALT) and alkaline Phosphatase(ALP), blood was obtained from tail stems of fish. The amount of enzymes was measured using photometric method and values ​​were expressed inU/L.
Results: The highest and lowest levels of liver enzymes in Epinephelus stoliczkae were: aspartate aminotransferase=198.16±6.21-298±10.28, alanine aminotransferase=38±2.56-81±2.19, alkanin phosphatase=118±4.21-177±2.7U/L.Over time, the amount of liver enzymes in different treatments increased compared to the control group and showed a statistically significant difference(P<0.05).For all three liver enzymes, the highest amount was recorded in the third treatment and 21 day and the lowest in the first treatment and time of 0.5 days.
Conclusion:In this experiment,liver enzymes increased in response to an increase of chromium concentration and duration of exposure, which could be due to damage the liver cells and release of liver enzymes into the plasma.In general, liver enzymes can be used as biomarkers of pollution in natural environments.
 

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The Persian Gulf has a different environment for corals compared to other parts of the world. 17 coral islands and some coastal areas in the northern part of the Persian Gulf as well as Chabahar Bay in the Oman Sea are the most important coral regions of Iran. The inaccessibility of coral islands and the dispersion of research have led to inaccurate information on the number of coral reef species identified. In this research, by field study of some coral regions such as Shidvar, Farsi, Kharg, Khargo, Hindurabi and Nayband, as well as collecting studies conducted by other researchers in other coral regions, thorough information about the diversity of coral species identified in the Persian Gulf have been presented. According to studies, the number of species of coral reefs identified in the Persian Gulf waters is 96 species, which by calculating 6 species of coral reefs that are reported only from Chabahar Bay, brings the number of species identified in Iranian waters to 102 species. The identified species are from 13 families and 40 genera, among which, Merulinidae and Acroporidae each with 29 and 23 species, respectively, have the highest diversity in terms of number of species. After these two families, Poritidae with 11 species has more diversity than other families. Among the studied islands, Larak Island has the highest number of species.

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In this study, the morphometric and meristic characteristics of Psettodes erumei in two regions of Bandar Abbas and Bandar Jask were investigated. Up to30 Psettodes erumei fish were prepared from each region and after performing bioassay operations, 29 morphometric characteristics and 9 meristic characteristics were measured and counted. According to the results, the average coefficients of variation in the morphometric characteristics of right-handed and left-handed fish in Bandar Abbas region are 0.34 and 0.41, respectively, and the average coefficient of variation of meristic factors of right-handed and left-handed fish is 0.14 and 0.17. The mean coefficients of variation of morphometric factors of right-handed and left-handed fish of Bandar Jask are 0.25 and 0.24, respectively, and the mean coefficient of variation of meristic factors of right-handed and left-handed fish is 0.10 and 0.10. Also, Psettodes erumei fish had a significant difference in 25 morphometric factors and 1 meristic factor between these regions (P <0.05). The height of the anterior fin, the height of the dorsal fin, the height of the ventral fin on the dark and light surface, the length of the base of the thoracic fin on the dark and light surface and the width of the mouth are the most important morphometric factors. There was no significant difference between the parameters measured in Psettodes erumei fish in any similar area (P> 0.05). According to these results, the differences between the morphometric and meristic characteristics are more pronounced, which is itself due to different environmental conditions in these two regions.

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The DINEOF algorithm is a parameter free technique based on iterative EOF analysis that is used to calculate the missing data in a given satellite data set (without requiring any prior information). In this study, the DINEOF technique has been used to fill the gaps in chlorophyll-a data series in the Persian Gulf and Oman Sea. Level 3 data (4 km spatial resolution) of chlorophyll-a concentration obtained from MODIS sensor (2003- 2020) for the study area were used. In some of the images several gaps were found in different months of the year. Images with gap in the Persian Gulf and Oman Sea were reconstructed by rtsa.gapfill R-package and DINEOF algorithm in R software. The linear regression analysis was performed between the missing and reconstructed data, and also parameters such as RMSE, MSE, MAD and SNR were calculated to evaluate the validity and performance of the DINEOF algorithm. The maximum number of the gaps in data series were found in July. Hence, the images of July have been examined and reconstructed as the case study. The original maps of chlorophyll-a concentration showed that the maximum number of the gaps were in July 2009 and 2015. Evaluation of the results showed a high accuracy of DINEOF-reconstruction method (e.g. in July 2014, R² = 0.83, RSME = 0.34, MAD = 0.14, MSE = 0.10). The results showed that the implementation of the DINEOF algorithm (in R) to reconstruct the gaps in chlorophyll-a concentration images could serve as a rapid and efficient technique.

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  Trichiurus lepturus is one of the most important and commericial species in the Persian Gulf and Oman Sea.In order to come up with the responsible fishing pattern,there was a need to identify  reproduction characteristics. Data were collected randomly from April 2019 to February 2020 from six major artisanal fish-landing sites in Hormuzgan Province (Bandar Parsian, Bandar Kong, Qeshm Island, Bandar Abbas, Bandar Sirik and Bandar Jask). In the detection of sexual stages, the 5-stage key of sexual maturity was used at the macroscopic level. In determining the spawning season, the gonado-somatic index(GSI) was used and its comparison in different months. The lowest GSI of female fish was in September (1.2). The highest GSI of male fish was determined in December with a value of 3.1 and after that in May 2.6. Examination of the GSI and reproductive stages showed two main spawning periods in the middle of spring and late autumn. Different sexual stages were seen in all months of the year, which indicated the batch spawning strategy in T. lepturus. During different months, significant differences in the sex ratio were observed, but during the investigation and in total, no significant difference was observed between the female: male sex ratio in the expected ratio of 1:1.The length at first maturity obtained 78.7 cm total length. It is necessary to ban fishing during the spawning season in order to protect the stocks of this species.
 

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Tuna fishes are one of the most important and commericial tuna species in Northern of the Persian Gulf and Oman Sea. The tuna fish stocks Thunnus tonggol was assessed in Hormuzgan coastal waters using software FiSAT . Data were collected minimum 200 fish per month simple randomly from five major traditional fish-landing sites in Hormuzgan Province, from November 2021 to September 2023. The monthly individuals ranging of T. tonggol  from 21 - 108 cm fork length with mean 71.08 ± 1.23 cm.The infinity length and growth parameters (K, L∞) for T. tonggol, were computed 121.17 cm and 0.68 respectively. Growth performance index (Phi Monreo) calculated for T. tonggol , 8.9 which was in agreement with the finding of the other studies in the Indian Ocean. The results showed that this species has a high growth rate in the first 2 years of their life. The (a, b) parameters in power equation length-weight relationship for T. tonggol were (0.00002, 2.94), indicating that T. tonggol has isometric growth. Total mortality, natural mortality, fishing mortality rate and exploitation ratio (Z, M, F, E) were estimated for T. tonggol (2.89, 0.71, 2.18, 0.75). These results indicated that population of T. tonggol  is overexploited and no scope for improving production in Hormuzgan Province. Tuna fish stock are trans boundaries and its fishery management  and long term monitoring programs would be conducted in collaboration countries bordering the Persian Gulf, Oman Sea and Indian Ocean

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The use of Artificial reefs(A.Rs) are one of the methods used to rehabilitation of fish stocks. This involves studying the grain size composition of bed sediments and  Total Dissolved Solids (TDS), which are crucial components in terms of their location. For this purpose, three stations with three repetitions were selected in the eastern and western of Jask City Bay and the study was conducted in the summer and winter seasons of 2023.In the study of total suspended solids, the minimum value with the mean and standard deviation was 25.9±0.46(mg/lit)at the fourth station in the Eastern basin during winter 2023. The maximum value with the mean and deviation was 36.39±0.62( mg/lit )at the third station in the western basin during summer 2023. The analysis of sediment grain size in the stations revealed that the lowest and highest amounts of sand and silt were found in the western basin at 76.4% (third station, summer 2023) and 88.5% (second station, winter2023) respectively. Firstly, the strength of the substrate (grain size) is the most essential factor in establishing structures, which contributes to ecological and biological success. Considering the optimal range of this component stations, suggested as the suitable areas for installation of A.Rs, one area(Western of  Jask City Bay) and two area(Eastern of  Jask City Bay), respectively. 

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General attention to carbonate sandshas been begun since the early 1960 in Iran. When the first bore drilled the Persian Gulf’s bed, it drew out layers of this soil type along with sand and shell. However, the large amount of carbonates in this soil was not first diagnosed. The first knowledge of the unique behavior of this type of soil was obtained during pile driving in the construction of an oil platform in Lavan Island, Persian Gulf, in 1968. In this operation, after a number of 30 inch pipe sank into the cemented soil for about 25 feet, they suddenly had a free fall with no resistance up to depth of 50 feet. Carbonate materials and aggregates can be found in nature in different shapes. The majority of them are made of calcium carbonate or other types of carbonate with soft and loose grains that can break easily. These soils are of remarkable importance in offshore engineering. Since early 70s, a great amount of studies have globally been conducted for identifying the unique engineering characteristics of carbonate sands. Different behavioral parameters including strain-stress behavior, shear strength, internal friction angle, volumetric behavior, elastic and shear modulus, Poisson’s ratio, carbonate content, shape of carbonate grains andetc have been studied. No certain laboratory methods or field study plan have yet been provided to obtain appropriate parameters for designing foundations in carbonate soils. Despite this, performing a number of laboratory and field experiments can be helpful. Executing at least amount of experiments to determine the following matters are essential: • Material composition, especially calcium carbonate content • The origin of the materials to distinguish between skeletal and non-skeletal deposits • The properties of the gains such as angularity, porosity, and initial void ratio • Compressibility of materials (using consolidation test) • Strength parameters of the materials, especially internal friction angle • Cementation, at least quantitatively In this paper, shear behavior of four skeletal carbonate sand samples obtained from the northern coasts of Persian Gulf and Oman Sea are investigated. Regarding some parameters of samples such as particle size distribution, physical properties, microscopic images of grains, compressibility, drained triaxial shear behavior, elastic modulus and internal friction angle it was attempted to promote geotechnical knowledge and improve civil engineers understandings of carbonate soils in this part of the world. On the basis of experimental tests like one-dimensional consolidation and triaxial tests, it was determined that despite a number of similarities between the shear behavior of carbonate sands, behaviorally they depend on the grains shape and size, initial particle size distribution and void ratio, calcium carbonate content, confining stresses and applied strains. Although all specimens were selected from the southern coasts of Iran, but a large number of difference was observed between them in terms of shear behavior and strength