Journal of Oceanography
Year:2016 | Volume:7 | Issue:26|Papers Count:11

In this study, the assumption was that the samples of Diogenes avarus are oriented to the empty shell of Gastropods based on visual information, and exposure to Pb pollutant, affects this ability. So, the orientation behavior towards the lateral and reverse sides of empty shells of four species of gastropods was studied in two groups of hermit crab, D. avarus, exposed to Pb and unexposed to Pb (Healthy) in a round environment. Healthy samples showed a significant orientation to the lateral and reverse side of Gastropod Umbonium vestiarium. While exposed samples showed the same orientation as the control group. Therefore, Pb pollutant has affected the behavior of visual orientation in samples. These observations may be due to the neurotoxin property or loss of energy by effect of detoxification and survival in conditions of stress.

In this study, spatial and temporal variability of physical and chemical factors and its effect on primary production was nvestigated in Mahshar, Zangi and the mouth of the Musa estuary creeks during a year from November 2013 to July 2014. Phytoplankton primary production was measured by the oxygen light and dark bottle technique, and High performance liquid chromatography (HPLC/UV-VIS) was used to detect and measure chlorophyll-a. The highest primary production (1.59 gc/m2/day) was obtained in April in the mouth of the Musa creek and the lowest (0.02 gc/m2/day) in October in the Zangi creek. Principal component analysis (PCA) reduced the data dimensionality from 18 environmental parameters to 4 principal components explaining about 84 % of the data variability. Comparison of primary production in three creeks in this study with other global zones showed that primary production is average.

Coral reefs are the most diverse of all marine ecosystems. Because of their environmental and scientific importance as bioaccumulator, the concentrations of Al, Cd, Ni and Pb in sediments, water and coral samples in Hengam Island were assessed using AAS. The elevated levels of heavy matels were observed in Acropora clathrata, Echinipora sp. and Sinularia sp. Calculated BAF resutls showed that all corals have a good ability to absorb Cadmium and Lead from water compared with sediments which is due to filter feeding nature of corals. The maximun and minimum concentration of heavy metal was observed in the stations 1 and 3 respectively in most studied corals. Considering water flows in the Persian Gulf, it can be concluded that station 1 is in contact with sea flows coming from Hormoz Strait, in contrast with station 3 which is located in a closed and confine area. Fossil fuels from fishing and passing boats seem to be the most important contaminating factor in Hengam Island.

Accumulated Gas Hydrates in seafloor sediments can be released in the atmosphere and the greenhouse effect of methane can exacerbate global warming. It is possible to estimate the stability of methane hydrate in the different physicochemical conditions by using physicochemical equations. In this study, by using a physicochemical equation and data of 641 points, stability of methane hydrate in different depth and locations of the Caspian Sea were calculated and potential maps of gas hydrate formation were presented. In the next stage, methane hydrate stability was measured in the different conditions in that the mean temperature of the Caspian Sea is increased 0.6 to 2oC by global warming and then the thickness changing of the methane hydrate zones was calculated. Then, based on the calculated thickness variations and geophysical evidences of gas hydrate in the Caspian Sea, released gas in the atmosphere for different scenarios were estimated. Result showed that a huge amount of methane gas, maybe around 369´1012 to 984´1012 m3, can be released in the atmosphere.

The Spatial and temporal variability of macrobenthos in the southern Caspian Sea (Chalus shore) were seasonally investigated from winter 2005 till fall 2006. Samples were taken with a Van Veen grab from depths of 7 and 20 meters along two transects, from Khate Hasht area (western part of coast) to Radio Darya area (eastern part of the coast). Totally, 5 classes of macrobenthos were identified in which the most abundant populations were Polychaeta 68.7% from abundance point of view. Density and biomass of macrobenthos in between seasons were significant (P<0.05), as the maximum density and biomass of macrobenthos were during the summer and autumn (4251.8±1419 ind/m2 and 475±243.8 g/m2), respectively while the minimum density and biomass were during the spring and winter (725.9±64.5 ind/m2 and 0.3±0.1 (ME±SE) g/m2). A significant correlation (P<0.05) between the density and biomass of macrobenthos with sand percentage and total organic atter (TOM) were found in different seasons. The maximum diversity and richness (1.60±0.29 and 1.52±0.27) were during the autumn in the depth of 20 meter of Khate Hasht area, respectively while the minimum (0.85±0.27 and 0.86±0.22) were during the spring in the same depth and area. The maximum evenness (0.91±0.05) were during the winter in the depth of 7 meter of Radio Darya area and the minimum (0.55±0.13) were during the summer in the depth of 7 meter of Khate Hasht area. According to the results of ecological indices (diversity, richness and evenness) and comparison with the proposed standards, stress and pollution in Chalus shores are moderate.

In the current research, tropical cyclone Haiyan (TCH) was focused and some meteorological parameters in the lower- and upper-levels of troposphere have been investigated. For this aim, five datasets including re-analysis and observational data have been used and some parameters including sea surface temperature, relative humidity, potential temperature, relative vorticity, vertical wind shear, geo-potential height, temperature and wind vector have been analyzed, based on latitude- ongitude distributions, vertical profiles and time series plots. Results indicated that all focused parameters in the lower levels of troposphere were disturbed from the beginning of TCH lifetime and also contributed in TCH intensification and weakening. owever, variation of the selected parameters at the upper part of troposphere started with a delay of about 2-3 days, they affect TCH intensification and weakening. Conclusively, it can be claimed that both lower- and upperlevels of troposphere have been changed during TCH and their positive interaction helped TCH to be intensified to category 5.

This study was carried out aiming to identify and evaluate the diversity and abundance of rounded crab larvae in Hengam Island coastal waters from winter to autumn 2011. Planktonic larvae of brachyuran crabs were sampled using 300 mm mesh net. Environmental factors such as temperature, salinity and dissolved oxygen were also measured. Seven species of brachyuran larvae were detected and the dominant species were Leptodius exaratus with 23% relative abundances. The most larval frequency of Brachyura was recorded in the summer (174.58±145.27 (Mean±SE) person per cubic meter) and the lowest in winter (8.75±9.97 (Mean±SE) person per cubic meter) respectively. The most larval frequency of Brachyura was recorded in the summer and the lowest in winter respectively. Abundance of the larvae and temperature showed a positive correlation (P<0.01) significantly using the spearman test. Shannon diversity index ranged between 0.17-1.08 that maximum was measured in the summer. In the present study larval stages f the Charybdis feriata, Pilumnus kempi, Menaethius monoceros, Menaethiops nodulosus and Xantho sp. were reported for the first time. Also, the species P. kempi and Xantho genus, that have not been reported from the Persian Gulf, was reported for the first time in this study.

In this study, the commercial seaweeds were cultivated in the Persian Gulf coastal areas. A culture system for two agarophyte and carrageenophyte seaweeds Gracilariopsis persica and Hypnea flagelliformis has been developed, using floating rope for grow-out. Correlations between RGR and environmental parameters were investigated using Pearson correlate Test. The results indicated that the highest biomass for Gp. persica (RGR=28.77±0.4% day-1) and H. flagelliformis (RGR=25.16±0.3% day-1) was obtained in February and January, respectively. In seaweed Gp. persica, positive correlation was found between RGR and O2 (r=0.558; P<0.001), and negative correlations were found between RGR and temperature (r=-0.657; P<0.001) and salinity (r=-0.607; P<0.001). In seaweed H. flagelliformis, negative correlation was found between RGR and temperature (r=-0.706; P<0.001). These results demonstrated the great potential of Gp. persica and H. flagelliformis for mariculture.

Heavy snow is one of the atmospheric hazards that sometimes occur in Gilan province. In this study, the maximum height of heavy snow location that occurred in February 2014 in Gilan province was recognized and the cause of the event was analyzed. For investigating this phenomenon, data from NCEP/NCAR (reanalysis), local synoptic stations, MODIS satellite image and WRF model were used. The results showed that the formation of a secondary high pressure center in the local scale, due to the cold advection forcing of Caucasus topography and the movement of cold air from Caucasus Mountains to the Kura plain caused to flow eastward wind cross with West-ward streams by polar high-pressure air mass which is located on the northeast of the Caspian Sea. The convergence of surface wind as the convergence band along the western shore of the Caspian Sea enters to a small range in the southern of Anzali Wetland. Cloud band is in accordance with the wind convergence zone that can be seen in the image of Terra satellite MODIS sensor and the Gilan radar precipitation intensity image. The maximum latent heat flux core on the Southern zone of the Caspian Sea as the thermodynamic forcing confirms the impact of regional factors on the spatial pattern of maximum snow depth in the East regions of Gilan.

In the present study, energy budget of dominant bivalve of the Oman Sea, Azumapecten ruschenbergerii, was evaluated at Chabahar Bay subjected to changes of temperature and food, before and after monsoon. Scope for growth (SFG) is used to indicate ecophysiological condition of animals. It is determined in studying energy budget. SFG values were calculated for seawater temperature, lower and higher temperatures, and also when pecten fed with different microalgae. Furthermore, enthalpy of its adductor muscle was calculated and subjected to statistical analysis. Averages of SFG values were negative before and positive after monsoon. SFG values were generally higher when fed with Microalgae Dunaliella sp. Moreover, despite of significant difference between SFG values before and after monsoon, enthalpies of adductor muscles (edible part) have not shown significant difference. So, this study suggests that 1) The above mentioned Microalgae has more feeding efficiency, 2) This mollusk had more excreting than absorbed energy and 3) It can be one of the best animals in aquaculture purposes and an effective factor to reduce blooming in aquatic areas.