فصلنامه اقیانوس شناسی
پیاپی 25 (بهار 1395)

The assessment of Tsunami propagation in the sea and ocean is the primary aim of this research. Tsunami propagation is generally simulated by solitary waves. In this research, for the simulation of solitary wave propagation in fluid with free surface, an exponential basis functions meshless method is introduced. The formulation of this method is based on Lagrangian form of Navier-stokes equations for non-viscous fluids based in pressure. In this regard, the Laplace equation of pressure is solved at each time step. Then, the geometry is updated based on the Lagrangian formulation of the motion through an implicit algorithm. Considering the changes of geometry in simulation time, the introduced meshless method is efficient and very quick in calculations. The results for water surface profile before breaking are in good agreement with experimental data.

The aim of this paper was to study monsoon effects on polychaetes population structure in subtidal area based on some biodiversity indices. Sediments sampling was carried out by grab van-veen from 12 subtidal stations in three time periods (pre-monsoon, monsoon and post-monsoon). The physical and chemical parameters were also recorded. Mean density of polychaetes were recorded 1101.2 ±614.3 ind/m2 (pre-monsoon), 428.9 ±316.2 ind/m2 (monsoon) and 588.8 ±313.3 ind/m2 (post-monsoon). Shanon diversity indices were 2.08, 1.63, 1.83 respectively. The Hill indices was reversed and showed highest number in monsoon season and minimum number in pre-monsoon. These results represented non-uniform polycheates distribution during pre-monsoon. Cluster analysis of each season showed that deep stations were in separate disturbances. During the summer monsoon, variations in environmental factors and bottom distractions affected the density and diversity of polychaetes and as a stressor reduced the diversity and density during the monsoon.

Ports, as a key link in the maritime transport chain, has a basic and decisive role in the economic development of the country's transportation and global trade, and about 90 percent of imports and exports activities of countries done through ports. This study identifies factors affecting the privatization of ports with the review of previous studies and based on the opinions of experts in this field using the Delphi technique and then analysis relationships between these factors using FUZZY DEMATEL model. The results showed the importance of the studied factors such as the factor of "infrastructure of privatization that includes culturalization and awareness in the country", which shows the high importance of this factor in the privatization of ports.

In this study, for measuring the concentration of nutrients (Nitrate, Nitrite, Phosphate and Silicate) throughout the Bardestan creek and its offshore waters during March (winter) and August 2014 (summer),samplings were carried out using a fishing boat. Nine stations in creek and nine stations in its offshore waters were selected. Surface seawater samples were collected in three replications. Samples were analyzed in the laboratory by colorimetric method for 54 samples in each season. Winter mean value of nitrate, nitrite, phosphate and silicate were 95.93 ±12.77, 5.45 ±0.71, 17.02 ±1.37 and 68.18 ±8.05 µgL-1, respectively. Also, summer mean value of nitrate, nitrite, phosphate and silicate were 120.84 ±13.58, 5.67 ±1.52, 10.99 ±0.26 and 89.66±21.89 µgL-1, respectively. Statistical analysis indicated significant difference between phosphate concentration in winter and summer (P0.05). Probably the difference in nutrient concentrations is due to change of seasons. The effect of winter rainfall in nutrients loading, especially in phosphate, throughout the Bardestan creek and its offshore waters in the Persian Gulf was observed in the present study.

The present study was aimed to determine the origin and concentration compounds in eggs of four sea-bird species residue in Banifaror Island. Sampling the studied species hatch was carried out in July 2012. After analyzing, the concentrations of these ingredients, including extraction, column chromatography and gas chromatography-spectroscopic two mass were determined. The origin of the nalkane compounds were determine using diagnostic ratios. Total obtained concentrations in the sampled eggs of Tern, White cheeked tern, Bridled tern, Greated crested tern and Lesser created tern were in range of 42.93-67.28, 24.48-95.64, 25.92-39.95 and 39.49-71.86 (µg.mg-1 lipid), respectively. The concentrations of these compounds in the eggs of White cheeked and Lesser created tern were more than Greated crested and Bridled tern. Origin of the compounds was recognized as petrogenic sources. The most important involving reasons are the contaminants of oil refineries, founded in closed to Banifaror Island, presence of oil pollutants caused by oil spills in the Persian Gulf, shipping, discharge of ballast water from ships to this area. As a conclusion, the eggs of four sea-bird species can be used as biomonitoring agent for n-alkanes in the studied area.

This study conducted for estimation of length and weight frequency, CPUE (catch per unit effort) and species composition caught by sardine’s Purse seine net in coastline of Jask within nine months in 2012. Random sampling was done 10-day per month by Fiberglass fishing boats. The results exhibited 75% of total catch were target species (Sardines) and Goldstripe ponyfish (Leiognathus daura) with 6.6% of total catch had maximum yield among the bycatch species. Maximum and minimum length frequency during May and January were calculated 16 and 12.1 (cm) respectively. Furthermore, Mean of total length was 14 (cm). Mean of weight, maximum and minimum weight frequency at July and January were 23, 29 and 15 (g) respectively. CPUE was calculated 136.1 kg /haul with 4.4 times shooting per day, catching catch per day.

The aim of this study was the survey of the surface microtriches of Dollfusiella spinulifera reported for the first time from the Persian Gulf. After isolating cestodes from five specimens of Himantura sp., first, the worms were stained for identification, of which, the best specimens were selected, unmounted in Xylene and after destaining finally dried in hexamethyldisilazane and examined with scanning electron microscopy. The results showed that except for the apex and distal bothrial surface, which are covered with papilliform filitriches and acicular filitriches, respectively, other surfaces were adorned with palmate spinitriches and filitriches (papilliform filitriches or acicular filitriches). In addition, the pattern of the surface microtriches was compared between Iranian population of this species from the Persian Gulf and the Australian specimens. The comparison revealed the difference in the microthrix pattern of these two conspecific allopatric populations.

Steady and unsteady experimental and numerical simulations are carried out in this paper to investigate saltwater intrusion mechanism into unconfined coastal aquifer. Laboratory results are compared to dispersive SEAWAT model to assess the applicability of numerical simulation. The dispersive SEAWAT model predicts salinities reasonably well comparing with sand-tank observation but it over predicts salt wedge toe position. Time reaching to steady state was almost equal in both physical and numerical modeling. In order to compare the mixing zone thickness, 5% and 95% salinity contours were also compared against laboratory data. The numerical results indicated partially wide mixing zone that is not observed in the experiments. Longitudinal dispersivity has been calibrated in the model to minimize the mixing zone thickness. Flow velocity components are also computed in this study by simple Darcy’s law and the freshwater and saltwater streamlines are depicted to visualize the flow adjacent the salt wedge and to observe the freshwater/saltwater movement toward exit point.

In the present research work, origination and modification of the zona radiata (ZR) around the rainbow trout oocytes and in the zygotes were studied for every stage of ovarian growth and its relationship with the habitat and spawning location. In early to mid-December, premature ovaries were separated from the matured fishes. One week later, the mature oocytes and sperm were caught with the massaging and pressing of the fish abdominal area and some mature oocytes were fertilized. Study of the histologic sections demonstrated that the ZR is appeared as a non-striated, amorphous and acellular area outside the oolemma of the oocyte during cortical alveolar stage. The number of canals and structural complexity of ZR were culminated at the vitellogenic stage. In mature oocytes, ZR became bilayer (ZRi, ZRe) and its structural complexity was reduced. This reduction continued in afterfertilization oocytes (zygotes) that could show a change in its role from nutritional type to protectoral one. It was appeared that jelly layer (ZRe) of rainbow trout eggs was simpler and thinner when compared to other fish eggs. The results achieved was logical because of spawning behavior of trout which lays oocytes in dogged spawning pits, therefore there was not any need for adhesion of oocytes on spawning substratum in order of protection.

This study was carrid out to determine the effect of feeding frequency on growth and biochemical factors of rearing juvenile ship sturgeon (Acipenser nudiventris). A 135 juvenile Acipenser nudiventris (85.57 ±3.95 gr. average initial weight) were stocked in 9 fiberglass tanks by volume 500 lit (fifteen fish per tank in each treatment) and reared in open system. Fish were fed 3% body Weight per day by institue commercial diet once at 8:00 am and two times at 8:00 am and 20:00 and three times at 8:00 , 15:00 and 23:00 in eight weeks, respectively. Biometry were carried out in 28 days interval. The fish wieght and length were recorded. Temprature and dissolve oxygen in water of each tanks was recorded daily. At the end of the rearing periods, any significant differences between the feed efficiancy ratio (FCR), Specific growth rate (SGR), Weight gain (WG) and condition factor (CF) (P>0.05) were not observed, but the result showed albumin increase in treatment 3 and a Cholesterol increase in treatment 1 (P0.05). The result showed that growth factors of Acipenser nudiventris were independent of feeding frequency.