فصلنامه اقیانوس شناسی
پیاپی 14 (تابستان 1392)

Submerged breakwaters are some type of effective coastal structures that are commonly being used to protect coastal area against erosion. Submerged breakwaters reduce wave energy approaching the beach by stimulating waves to break and dissipate their energy over the structure. In present study، a new approach toward numerical modeling (using the roller model) of shoreline response to a multi-purpose V-shaped submerged breakwater has been presented. The results of a series of 2DH numerical modeling tests indicate that shoreline response to multi-purpose V-shaped submerged breakwater scan varies between erosive and accretive، depending on the offshore distance to the structure. Breakwater crest level has significant impact on the magnitude of shoreline response، but not on the mode of shoreline response (i. e. erosion vs. accretion).

Due to the lack of measurements in many regions، wave characteristics are estimated using different methods. Wave climate hindcasting/forecasting is mostly conducted by numerical models or empirical methods. Until now، different empirical methods have been developed for wave hindcasting. However، with the development of high speed processors، several sophisticated numerical models have been developed for wave prediction. These models are mostly phase-averaged spectral wave models developed in three generations. In the last two decades، third generation wave models have been used widely in academic and practical projects. In this regard، Port and Maritime Organization has produced his own model، PMO Dynamic. This model has been developed as a part of first three phases of Monitoring and Modeling of Study of Iranian Coasts project. PMO Dynamic package is a software available for engineering purposes. It has several modules that have been developed for different objectives. Wave model is the module which is used for the generation and transformation of wind waves in coastal areas. In this paper، in order to test the PMO Dynamic model capabilities، it has been applied for the prediction of wave parameters in Bushehr Bay and the results have been compared with MIKE21 SW model and measured data.

Heavy metals have caused many environmental problems in aquatic ecosystems. These elements enter into the environment by natural factors، industrial activities، agriculture and urban sewages and can accumulate in aquatic organisms through the food chain. Mangroves as a food chain ring are able to adsorb heavy metals and can indicate elements concentrations in the ecosystem. In this study، to determine the concentration of heavy metals (Cu، Pb، Ni، Cd) in sediments and mangroves in Imam Khomeini Port and to investigate the mobility of these metals based on enrichment factor، nine stations were selected and samples collected from mangrove’s leaves، roots، and sediments. The samples were digested in concentrated acid and metal concentrations were determined using atomic absorption. Results showed that metal concentrations in the roots of plants were more than in the leaves and there was a significant correlation between concentrations of metals in the sediment and plant roots. Therefore، mangrove roots can be a good biomonitor for polluted sediments with heavy metals. The average of enrichment coefficients in leaves and roots of mangroves for all metals was less than 1، that shows accumulation and availability are medium in this plant.

In this study، surface sediment samples (n=20) from Bandar Abbas were chemically analyzed to determine total concentration of lead and cadmium and their sources. The sampling was performed from two stations; Terminal of Bandar Abbas and Tourist Park of Soro، located in Hormozgan province in spring 2011. Direct Aqua Regia digestion method، sequential extraction techniques and subsequently Graphite Furnace Atomic Absorption Spectrometry (GFAAS) were used to determine total concentrations of Pb and Cd in geochemical sectors of the sediments. The results demonstrated that total concentration of Pb and Cd varied from 593. 7 to 1206. 2 and from 29. 3 to 30. 5 ng g-1، respectively. The resistant fraction of total concentration was about 62. 5 and 79. 1 percent for Pb and 73. 4 and 71. 2 percent for Cd in the sediments of Terminal of Bandar Abbas and Tourist Park of Soro، respectively. It reveals that more than half of the total lead and cadmium in coastal sediments of the stations originated from natural sources. High ratio of this fraction in the sediments showed that anthropogenic sources of metal pollution in the coastal stations of the sampling areas have fewer role and elevated concentrations of the elements in this fraction is due to the higher values of them، which are occurred naturally in the earth''s crust.

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 oil pollution in the Persian Gulf is considerable. Vanadium and Nickel are by far the largest traced metal constituents of crude oil. Their presence in high concentration in marine sediments may indicate direct input from oil pollutants. Therefore، Vanadium and Nickel are two important indicators of oil pollution. In this study، concentrations of these elements as well as their ratio (V/Ni) in the rocky shore oysters (Saccostera cucullata) and in the sediments of Bushehr province coasts were determined. The sampling and analysis were performed in February 2012. Samples were collected from rocky shores of four stations; Genaveh، Bushehr، Dayer and Nyband Gulf. The samples were acid digested and analyzed for heavy metal content using an Atomic Absorption Spectrophotometer (YOUNGLIN، Model ASS 8020). The average concentrations of Ni and V in the sediment samples were varied from 22. 48 to 51. 10 μg/g dry weight and 7. 64 to 31. 53 μg/g dry weight، respectively. While their average concentrations in oyster sample were varied from 4. 22 to 10. 51 μg/g dry weight and 1. 26 to 6. 2 μg/g dry weight، respectively. The V/Ni ratios of the Persian Gulf crude oil/residues do not correlate with those of the sediments due to the alteration of the relationship between the two metals in the sediments. Based on Muller geochemical index (Igeo)، sediment quality for Ni and V is in class 0 (unpolluted).

This study revealed that the dissolved oxygen level، biogenic content، bioturbation and particles size control the distribution of total organic carbon (TOC) in the surfacial sediments of Northern part of the Persian Gulf (from Strait of Hormoz to Khowr-e-Mussa). 525 surface sediment samples taken between 10 and 100 m water depth with Van Veen Grab were analyzed for biogenic content (bioturbating organisms)، TOC (Rock-Eval Pyrolysis)، mineralogy and particles size. Bed sediments are composed of terrigenous (quartz، feldspar، rock fragment and clay minerals) and chemical-biochemical (bivalve، gastropod، ostracod، bryozoa، planktonic and benthic foraminifera، echinoderm spine and fish notochord) particles. Based on these studies، muddy sediments، total organic carbon (0. 03 to 1. 48 wt%) and planktonic foraminifera (such as cyclomina and globorotalides) are increased and dissolved oxygen level (5 to 6. 2 ppm) is decreased in deeper parts of eastern and middle sections of studied area than coastal area which indicates high potential for organic matter preservation in muddy sediments of the Persian Gulf with lower dissolved oxygen level and lower bioturbation (decrease in benthic content).

The aim of this study was to find the relations between macro-benthos dominant orders and environmental parameters using mono and multivariate analysis in the southern part of the Caspian Sea in 2009-2010. 160 samples were collected in four seasons and in eight transects perpendicular to the coast from depths of 5، 10، 20، 50 and 100 meters. Results of the current study showed that Polychaeta had the highest abundance compared to other main orders (Oligochaeta and Crustacea). Results also indicated that CCA test was more compatible with ecological evidences compared to mono and other multivarite anaylysis (PCA). The CCA results showed that Polychaeta was in inverse relationship with TOM and siltclay، while the Oligochaeta was directly related to sediments characteristics (TOM) and in inverse relationship with environmental parameter (DO%). The dominance of deposit feeder group of Polychaeta (Streblospio genus from Spionidae) indicates high level of organic matter in sediment and trophic status of ecosystem.

Anionic detergents have the highest consumption among the detergents and are one of the pollutants of aquatic systems. In the present study، the effects of these detergents on hematological parameters of Hypophthalmichthys molitrix were investigated. For this purpose، three treatments containing anionic detergent concentrations of 0. 5، 1 and 1. 5 ppm and also one control treatment (no detergent) was considered. The fish were exposed to this material for two weeks. Blood samples from the caudal fin vein (with a 2 cc syringe) were taken. Blood samples were used to determine hematocrit، hemoglobin، red and white blood cell count and MCV، MCH and MCHC indices. According to the result، the values obtained by measuring the levels of hematocrit، hemoglobin and white blood cell count decreased significantly compared to the control treatment (P<0. 05). But the number of red blood cells، unlike other blood parameters in the control treatment was lower than the other treatments (P<0. 05) and the highest amount was observed in the 0. 5 ppm treatment (P<0. 05). The highest and lowest levels of MCV and MCH indices were measured in control and 0. 5 ppm treatment، respectively (P<0. 05). The MCHC index did not show significant differences among the treatments (P>0. 05). In general، it seems that even low concentrations of anionic detergents can make important changes in hematological parameters، hematopoiesis processes، and even non-specific immune system of silver carp. Therefore، the high consumption of detergents and their entrance into the aquatic systems can lead to failures in reproduction and breeding of this commercial species.

Sponges are important components of the Persian Gulf animal communities. In this research، ecological characterization of the marine sponge، family: Haliclonidae (Haliclona simulans and Haliclona oculata) on Artificial Reefs (ARs) of Bahrakan in Northwest of the Persian Gulf was studied. Seasonal variations in biomass and productivity in two species of sponges were estimated. The sampling was carried out (from May 2009 to February 2010) by using SCUBA diving at 12m depth by throwing quadrate (0. 25×0. 25) randomly. 4 sites (A، B، C and D) were selected for sampling، one site were placed on old artificial reef (D) and three others on new artificial reef (A، B and C). Sponge production in ARs was studied over one year period. In both species، biomass peaks were found in February and March (Winter). The minimal production during the period of study was recorded in warm seasons. The average production for H. simulans and H. oculata was: 7. 01 gAFDMm-2yr-1، yielding P/B ratio of 0. 88 and 7. 39 gAFDMm-2yr-1، yielding P/B ratio of 0. 30، respectively. Chemical and physical factors (temperate، salinity and DO) of water in each season were measured and their relationships with biomass of sponges were compared. The results of relation between physicochemical properties of water and sponges biomass showed that the increase in salinity during cold seasons corresponded with increased biomass of vice versa.

This study was carried out on the community variations of zooplankton in different depths (5-100m) at 8 stations in 2008. Samples were collected through a zooplankton net (100 μm mesh) by R/V Gilan vessel. The most abundant zooplankton and its biomass were in depth of 5m in all seasons، but abundance decreased from coastal area towards deeper area as 74% (Spring and Summer)، 57% (Autumn) and 70% (Winter) of zooplankton community were in depths of 5 and 10m. The Copepoda constituted the main community in different depths and seasons during the year. This group was distributed with the abundance of 164 ind/m3 in depth of 100m in spring to 11289 ind/m3 in depth of 5m in summer during the year. The Rotatoria community increased in winter and it formed 48% of zooplankton abundance and 74% of its biomass. Its abundance decreased in spring and summer، but it increased during fall again.