فصلنامه اقیانوس شناسی
پیاپی 35 (پاییز 1397)

The Caspian Sea is sensitive to anthropogenic impacts as it is isolate from other seas. The environment pollutions strikingly increased in the last years. The impact of fish cage culture on the phytoplankton community was studied at the 3 stations near the cage and the 3 stations of references in the southern Caspian Sea during January and April 2013. A total of 19 phytoplankton taxa belonging to diatoms (12 species), chlorophytes (2 species), cyanophytes (2 species), and dinoflagellates (3 species) were identified at the study area. The diatoms abundance was dominated (86 % total abundance) in the study. The finding showed, the abundance of exotic species as diatoms Pseudosolenia calcar-avis and Pseudo-nitzschia seriata were dominated at beside of the fish cage culture stations as compared with the reference stations. The PCA analysis confirmed significant difference between abundance of phytoplankton at the fish cage culture stations and the reference stations. Furthermore, CCA analysis confirmed that there were strong relationship between diatoms, cyanophytes and nutrients levels (r = 0.82).
The reasons of high phytoplankton abundance and exotic species at beside of the fish cage culture stations could be related to the high nutrients concentrations due to fish nutrition and fecal. This study performed during the short periods, so the effect of fish cage culture on the Caspian Sea ecosystem should be taken into account in future studies.

Stress reduce animal’s fitness with affecting to animal’s metabolic function, the aim of this research was to study of stress controlling function of C.Umbonella in exposure to change in grain size sediments at Kangan and Assaluyeh coastline. Five sites including 11 stations were selected. Regarding to measurement of antioxidant enzymes, Soft tissue of 192 records were extracted. Higher value of CAT enzyme reported in stations at the near stress point in site 1 (49.76 ± 1.48 U mg-1 P) and site 2 (49.64 ± 7.51 U mg-1 P). unlike to values of GR and GPx enzymes, there were no significant difference (significant value 5%) in values of CAT and SOD along to the sites and stations. proposed that CAT and SOD enzymes have better efficiency during Alarm stages but GR and GPx are more effective along the Resistant stage in exposure to stress.

The shoreline is a very dynamic environment. Its situation is influenced on sea level changes, erosion and sedimentation processes, and its displacement has overshadowed human life, communications, and coastal facilities. The purpose of this study is to measure and compare the shoreline changes in the Gorganroud Delta and Sefidrouad Delta by The Digital Shoreline Analysis System (DSAS). In this study, after applying NDWI Index and high pass filtering, the shorelines extracts from the TM and OLI sensors for the years 1986, 2000, and 2015. In order to measure the shoreline changes, transects are considered at intervals of 50 meters perpendicular to the baseline. This step is done in Arc GIS software by DSAS extension.
The results show that the effect of sea level changes on displacement of shoreline is not the same in the both of studied areas. By the increase of sea level in 2000, the shoreline moved landward, while in 2015, due to the drop in sea level, shoreline moved seaward. During this 30-year period, the total rate of change are estimated in Gorganroud Delta and Sefidroud Delta 104/85 and -2/1 in meters/year respectively. With respect to these measurement, the Gorganroud Delta has shown remarkable retrogression and the Sefidroud Delta has shown little change. Also, the shoreline changes in the two above mentioned deltas indicate that the amount of sediment load transported by rivers plays an important role in controlling the shoreline.

It has become common to use a solitary wave as a model of tsunami waves. Smooth particle Hydrodynamic method (SPH) is without grid and based on the particle. This method is good for simulation of the nonlinear waves and generally free surface problems. The aim of this research is investigation the impact of non-linear slope beaches compared to that linear mode on run up solitary wave by SPH method. Also wave hydrodynamic properties are investigated in different time intervals. Comparison the experimental and analytical method are showed that present SPH method Percentage error is about 3.5 percent compared to experimental data. So it can be concluded that the presented SPH method has high accuracy to run up calculation for different Slopes. Results showed that solitary wave run up on the nonlinear slope beach is more than linear mode. Also difference in solitary wave run up value in linear and nonlinear slop increase by increasing the curvature of the slope

The purpose of this study is to investigate interpolation methods for estimating and rehabilitating climate data. Due to the fact that two factors of rainfall and temperature are known as the most effective parameters in many applied decisions and in many studies of land physics, agriculture, hydrology, etc., climatic data are used. But climatic data are not always available at all intervals, or researchers need weather data to predict climatic conditions. In these cases, different interpolation methods are used. Therefore, in this research, existing methods for interpolation of climatic data in Ramsar, Babolsar and Bandar Anzali cities were evaluated. The results of the research indicate that the Neville and Spline interpolations provide a more accurate approximation for all studied cities. Other findings of the study are that temperature interpolation for the months of the summer season is less than the winter. There was also no significant difference between interpolations for different cities

In the present study, the Aden Gulf water masses have been Detected using a concentration passive tracer with the MITgcm model. The modeling domain in the range 0.5-30°N, 44-77°E includes the Persian Gulf, the Arabian Sea, and the Gulf of Aden. The initial data is appropriate to the model and modeling has been runed for 20 years. Comparing the results of the model with the measured data shows a good agreement. The results of modeling indicate that there are three water masses up to 900 meters deep (modeled depth) in the Gulf of Aden, which is well suited to previous researchs. The Aden Gulf surface water mass is to the depth of 100-200 meters with a maximum salinity of 37 psu and density of 1023-1024 , The water mass of the Aden Gulf's intermediate layers with a salinity of 35.9 to 36.9 psu and density of 1024-1026 at a depth of 100-600m and water mass of the ​​Red Sea with salinity of 35.9-36.9 psu and density 1026-1027.5 located at depths of 400-900 meters and below. The horizontal density gradient due to salinity changes between the Red Sea salty water and the low salty water of the Gulf of Aden leads to the creation of baroclinic instability. The difference in salinity between these two water masses due to turbulent mixing Causes Entrainment, which is minimized in the summer, the causing of Red Sea hot and salty water will be distributed more than winter. The calculation of the density ratio represents the establishment of a thermohaline convective regime between the Gulf of Aden water masses.The results of the release of passive tracer with a concentration of 100% in the Gulf of Aden from surface to depth also confirm the existence of three water masses. The surface plume spread to the length of the 46 after 270 days under the influence surface currents of the Gulf of Aden. The output of plume at depths of 200 and 400 meters in two northern and southern channels extended to 47 after 270 days in the Gulf of Aden. The critical width of the Red Sea flow for separation from the coastal boundary is calculated by calculating the radius of Rossby deformation for the winter of 30.25 km and 50.4 km in the winter.

The objective of the present work was to investigate the removal of cadmium by red algae Gracilaria as biomass. The effects of independent variable on biosorption of cadmium ion on the red algae Gracilaria as biomass were evaluated. The experimental data were analyzed via two custom isotherm models, i.e., Langmuir and Freundlich. The design of the experimental was developed for evaluate cooperating effects of pH, contact time, temperature, biomass dosage and initial metal concentration. The Box-Behnken model in response surface modeling was used for the optimization of the experimental data in Minitab software. The five parameters were fitted into second order polynomial equation and a mathematical function was developed. Statistical significance of coefficients in the second order polynomial equation are evaluated by t-test and p-value. The modified equation can be used for prediction of biosorption in any conditions.

The present study was aimed to investigate the histological structure of male gonad as an important organ of the reproduction and survival in the blue swimming crab Portunus segnis in Persian Gulf. In this regard, 20 blue swimming crab caught from the coasts of Hendijan in Khuzestan Province from September to June,2016. After anesthesia and morphological examination, samples were examined using common histological method. Based on the results, testis was surrounded by connective tissue.The connective tissue lamellae are divided testicular parenchyma into a number of specific lobules. Testis lobules have a Germinal Zone and a Transformation Zone. Vas deferens has three anterior, medial and posterior portions. The three portions surrounded externally by connective tissue and internally by cuboidal and culomnar epithelium. Spermatophores are observed in all three portions of vas deferens.