Journal of Oceanography
Year:2011 | Volume:2 | Issue:7|Papers Count:15

This paper aims to identify the main factors affecting seafarers' attraction and retention as a result of an empirical survey. The main objective of this research is studying the effect of workplace environment in conjunction with the type and class of ships on seafarers' attraction and retention by focusing on containerships, bulk carriers, and tankers. In this study, different items associated with retention and attraction of seafarers are self-assessed by respondents using a 5-point Likert scale from ‘Strongly Disagree’ to ‘Strongly Agree’. The respondents are randomly selected from the seafarers of three main Iranian shipping lines, including NITC, IRISL, and BOSACO. In comparison with the two other types of ships, tankers' seafarers are most satisfied with their working condition.

At present study, leg welding joints of Super M2 Jack up are evaluated by structural analysis. By reviewing other researches, it is recognized that jack up joints were analyzed by applying simplified supports. In this research, another method is developed.At first, considering the Persian Gulf environment, jack up platform model was generated and analyzed deterministically, then critical joint by considering welding volume was modeled in finite element software and it was analyzed by applying displacements of neighbor joints (by using the results of Jack up platform analysis) as its boundary condition. By analyzing the model, it is considered that using displacements of vicinity joints around the critical joint as boundary condition has more accurate results than applying simplified support; also Super M2 jack up platform has reasonable structural strength in Persian gulf conditions. Finally, according to the truss shape of legs, changing of direction for environmental forces do not have essential effects on magnitudes of maximum stresses in legs structure, but the positions of occurrence is variable.

The Persian Gulf area has approximately two-thirds of the words oil resources and many of the marine ecosystems of its areas are seriously threatened by oil pollution. Therefore, the study on the status of pollution Persian Gulf’s is considerable. Polycyclic aromatic hydrocarbons (PAHs) are one of the major groups of chemical pollutants owing to their widespread distribution in the environment and carcinogenic and mutagenic effects on living organisms. In this study, concentrations of 14 PAHs and their sources in the seawater of boushehr province in two seasons were determined. Samples of seawater were collected from four sampling sites, namely Genaveh, Boushehr, Dayyer, and Nyband Gulf.Collected samples were immediately transferred to hexane rinsed glass jars withaluminum foil inserts and transported in dry ice to the laboratory of PGRSC and kept frozen at -20oC prior to analysis. Seawater samples were extracted using a liquid-liquid extraction (LLE). The recovery of PAHs were more than %70. The total concentrations of 14PAHs in seawater was ranged from 1.5 to 5.9 ng/l.The results showed that concentration of PAHs in surface seawater in the inter-tidal areas of Boushehr province is very low, comparing to other areas of Persian Gulf and world wide.The highest concentration was observed at Nyband station. The results of study suggested that the main sources of PAHs in coastal areas of boushehr province is a mixture of both pyrolitic and petrogenic with predominant petrogenic imputs. Three- and four-ring PAH were the most abundant compounds among the 14 PAH investigated in surface seawater samples.

The objective of current study was to investigative the population ecology of Macro benthos of Gabrik Creek protected area in Jask city (Oman Sampling was conducted from autumn 2009 to summer 2010, by Van Veen Grab with area of 0/25 m2 and depth of 10 cm in three stations in Mouth, middle and end of creek). Enviromental parametrs consist of temperature, salinity, dissolved oxygen, turbility, electrical conductivity and pH, analysis of sediment texture and organic matter contents were also measured. The results showed that Bivalves were the most abundance with a percentage of 42 and Gastropoda, the lowest abundance with 10 percentage frequency of Macrobenthos was increased from mouth to the end of creek. In this study, 53 species belonging to 31 genera of Macrobenthos were identified and counted. The Results of ecological indicators was including Shannon Weiner (0.69±0.19), Simpson (0.19±0.15) and Margalef (17.39±8.51), respectively. According to the results, the frequency and diversity were decreased in hot seasons and the most important factor that affected these fluctuations was temperature. The results showed that in Jask protected area, a total of 53 species belonging to 31 families were identified. Macrobenthos of Mangrove forests has high diversity. Organic matter contents of bottom sediments were relatively high that was probably due to the sediment grain size that was silty-clay type.

The present experiment was conducted to examine the effect of dietary nucleotides on complements C3 and C4 and resistance of rainbow trout fingerlings to Streptococcus iniae. A basal diet supplemented with 0 (control), 0.05, 0.1, 0.15 and 0.2 percent to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish with initial average weight of approximately 23 g. After 8 weeks of feeding trial, levels of serum complements C3 and C4 in fish fed the nucleotide-supplemented diets were significantly higher than that of the control group. Fish were challenged by an intracoelomic injection with 9x106 colony-forming units/ml S. iniae. Mortality rate was recorded for 3 weeks after bacterial challenge. The challenge experiment showed that survival increased significantly (P<0.05) in fish fed the nucleotide-supplemented diets lower than of control treatment. The results suggest that dietary nucleotides administration at 0.15 and 0.2 percent exerted positive effects on serum complements C3 and C4 and resistance against S. iniae in rainbow trout.

Length composition, growth, mortality and exploitation rate of King fish, Scomberomorus commerson, was studied in the coastal waters of Boushehr Province, Persian Gulf 2008 and 2009. In total, 5801 S. commerson were sampled at random from tree major landings in the study area. This study covered all the length classes over a one year period. Fork length ranged from 13 to 131 cm. The FiSAT software was used to estimate the growth parameters of the von Bertalanffy growth equation. The von Bertalanffy growth equation could be written as L=137.34 [1-exp (-0.35 (t+0.31))]. Growth performance index was 3.82. Mortality rates were Z=1.81 year-1, M=0.448 year-1 and F=1.36 year-1 for total, natural and fishing mortality, respectively. The exploitation rate, E was estimated to be 0.75.The annual instantaneous rate of fishing mortality (F=1.36 year-1) was considerably greater than the target (Fopt=0.22 year-1) and limit (Flimit= 0.29 year-1) biological reference points, indicating that the stock is overexploited.

To identify the diversity of sea cucumbers with the aim of assessing sea cucumbers comprehensively in various habitats and regions, specimens were collected from 15 different parts on the intertidal flats of this island, mainly from north and south coasts. Sampling was done three times (from1388 to 1389) during summer, winter and spring.After transferring the specimen to the lab, spicules were extracted from all specimens and were used for identification The identification of the samples was done by using some valid identification keys to recognize their genera.On this basis, 6 species of Holothurians from Holothuriidea family were identified as: Holothuria parva, Holothuria arenicola, Holothuria cineraceus, Holothuria hilla, Holothuria leucospilota and Holothuria pardalis.

This survey is conducted to study diets and some feeding indices of dominant and commercial Juvenile Johnius bleangerii and Pennahia macrophthalamus species in Khuzestan coastal waters. The stomach contents of 87 Johnius bleangerii and 75 Pennahia macrophthalamus individuals were analyzed and captured by shrimp trawl net every month in main fishing areas of Khuzestan province from March 2006 to December 2007. The stomach contents of 87 individuals juvenile Johnius bleangerii were analyzed out of which 26.4% were empty and 73.6% had food items and For 75 individual’s juvenile Pennahia macrophthalamus 30.6% were empty and 69.4% had food items. The results of vacuity index for juvenile Johnius bleangerii showed the highest value and lowest value of Feeding Intensity index in December and the lowest value of vacuity index and highest value of Feeding Intensity in September and August. The results of vacuity index for juvenile Pennahia macrophthalamus showed the highest value and lowest value of Feeding Intensity index in November, December and April and the lowest value of vacuity index and highest value of Feeding Intensity in September. The result showed that Crustacean, Fish, Shrimp, Brachyuran and Bryozoans are the main food sources for juvenile bleangerii Johnius and for juvenile Pennahia macrophthalamus fish, shrimp, Brachyuran and Algae are the main food sources.