نشریه پژوهش های علوم و فنون دریایی
سال هفتم شماره 4 (زمستان 1391)

Urmia Lake is the second largest salt lake in the world and one scarce perennial hyper saline lake. It has wide biodiversity of halophile and halotolerant microorganisms. In this study, members of the genus Halomonas including moderate halophiles bacteria were isolated from Urmia Lake and their phenotypic and genotypic properties were studied. Samples were collected from different sites of Urmia Lake and were transferred to the laboratory under sterile condition. Then Alkaline Peptone Water (APW), Nutrient Broth (NB), Nutrient Agar (NA), MacConkey Agar (MAC) supplemented with 5% and 10% salt were used for isolations. These cultures were incubated at 35-37 ˚C for 48h and repeated cultures were performed for achievement of pure cultures. Finally 80 isolates were produced. These isolates based on morphological characteristics and phenotypic surveyswere studied. Also biochemical, characterization and salinity tolerant tests were carried out on the isolated strains.For genotypic and phylogenetic studies, 15 isolates were selected for genetic experiment based on 16S rRNA gene sequence. Therefore genomic DNA of selective bacteria was extracted and was amplified by PCR technique. The results of sequencing 16S rRNA were edited by dependent softwares and sequences similarity of these strains were analyzed on comparison with registered strains in Gen-Bank of EzTaxon database. 6 isolates belonged to Halomonas sp. that phylogenetic tree was constructed by the neighbor-joining method. From the phylogenetic viewpoint, these strains belonged to Halomonas janggokensis, Halomonas gomseomensis, Halomonas boliviensis and Halomonas andesensis species. Sequence similarities of Halomonas janggokensis and Halomonas gomseomensis were more than 99%. Sequence similarities for Halomonas boliviensis and the half of isolated Halomonas andesensis showed between 97% and 98.9%. The half of other Halomonas andesensis indicated 94.2% .

The rock lobster, Panulirus homarus Linnaeus, 1758 is an important fisheries product of south east waters of Iran. Lobster resources have decreased in recent years due to high fishing. So, stock enhancement activities based on ecological characteristics of the lobster habitats must be considered. Water and sediment samples of the lobster habitats in Ramin, at south of Chahbahar Bay were collected monthly from January to December 2000, by diving. Yearly mean water temperature was 25.56 ±2.8°C with maximum and minimum amounts in May and February, respectively. Yearly means of water salinity, dissolved oxygen, pH and turbidity were 38.77± 1.71 g/lit, 6.07 ±1.12mg/lit, 8.22 ±0.17 and 3.03 ±2.98, respectively. Yearly frequency of macrobenthos was 133 individuals/m2. Maximum and minimum frequencies of macrobenthos were observed in May and November respectively. Dominant groups of macrobentos were cephalochordata, polychaeta, nematoda, ostracoda, gastropoda, bivalves and amphipoda. Yearly mean weight and carapace length of the collected lobsters were 370.68 ±13.06 g and 71.36 ±15.85 cm, respectively. Increasing water temperature correlated significantly with macrobenthos frequency (p

Water pollution by heavy metals causes serious ecological problems in the world. Therefore, today determination of heavy metals such as Co and Cu in the environmental samples is required. Amberlite XAD-4 (polystyrene-divinylbenzene polymer) is a frequently used resin in analyses methods, thanks to its good physical and chemical properties, such as porosity, high surface area, durability and purity. In this study, Co and Cu ions were adsorbed during passage through amberlite XAD-4 resin. Also the influence of pH was studied and the best pH for this study was between 6 and 7.5 with a recovery of higher than 90%. The proposed procedure was applied for Co and Cu determination by Flame Atomic Adsorption Spectroscopy (FAAS) in natural water samples. The achieved recovery and its standard deviation, measured by standard addition technique showed that the proposed procedure had good accuracy, enrichmant factor, preconcentration factor and simplicity.

In present research biomass, frequency and distribution of macrobenthos in Gorgan Bay was studied in 8 stations in 4 seasons in 2009. Sampling was done by Van Ven Grab in 3 replicates in each station. Identified macrobenthos belonged to 13 families. The most abundant family was Ampharetidae (76%) compared to total population of macrobenthos. Balanidae (10%), Cardiidae (6%) and Nereidae (4%) had the next abundance. Maximum biomass of macrobebthos was observed in Cardiidae (45%), Balanidae (44.78%), Nereidae (5.8%) and Tubificidae (5.27%), respectively. The greatest frequency of macrobenthos was found in spring with 4110/m2 and the least was in winter with 29.25/m2. Maximum and minimum of biomass was observed in spring (33.568 g/m2) and winter (.080 g/m2) respectively.

Respiration and oxygen consumption in aquatic invertebrates including Gammarus (Crustacea: Amphipoda) are affected by osmotic pressure and salinity. This effect was investigated in three species from ecologically different springs in Fars Province. Oxygen consumption was measured for 1 hour period in various salinities (2 - 10 ppt) using a dissolved oxygen probe. Results showed significant differences in oxygen consumption in salinities 4 - 10 ppt. Oxygen consumption in all three species increased from salinity 2 - 6 ppt, and decreased with increasing salinity to 8 - 10 ppt. It was also significantly higher in salinities of 6 - 8 ppt in G. crinicaudatus, compared to other species. Regarding salinity differences in the environments of these species, it can be said that G. crinicaudatus has more tolerance and adaptability to salinity increase compared to the other two species. The higher oxygen consumption suggests that 6 ppt salinity was critical for all the three species. These three species have probably derived from a common ancestor diverging in time after geographical isolation of its descendant populations. The difference in their physiological responses could be a reflection of adaptation pressures, particularly osmotic conditions of their environments.

Recently, the ecology of the Caspian Sea has undergone with increasing development of human activities and industrial wastewater discharges. Heavy metal compounds are undegredable pollutants and are able to accumulate in the environment. They can affect the food chain and biological individuals such as fish species. 40 and 22 samples of Rutilus frisii kutum and Liza saliens were collected in central and eastern parts of southern Caspian Sea in 2008, respectively. All samples were analyzed based on standard methods using Atomic Absorption instrument (Thermo, M5 model). Results of this study showed that the amount of Zn in fish muscle of L. saliens was maximum (415.3±196.3 µg/g. dw). The concentrations of Cu, Ni, Pb, Cd and Hg in fish muscle of L. saliens were 10.85 ±11.02, 0.41 ±0.84, 2.63 ±2.67, 0.63 ±1.07 and 1.30 ±0.16 µg/g. dw, respectively. The concentrations of Cu, Ni, Pb, Cd and Hg in fish muscle of R. frisii kutum were 0.40 ±0.46, 0.0132 ±0.007 and 1.26 ±0.75 µg/g. dw, respectively. 7 heavy metals were below the established limits of different countries. The pearson correlation analysis showed that between Zn and Hg there were a significant negative correlation indicating a decrease of Hg toxcicity with increasing Zn concentration. THQs for individual metals were lower than USEPA guidelines value of 1 in young and adults human. Thus, consumption of 6 kg R. frisii kutum and/or L. saliens per capita cannot be risky for young and adults consumers.

Hail related to summertime thunderstorms is a small-scale phenomenon, and it often has short time duration. Hail will be produced by a thunderstorm for typically a fraction of an hour, and the width of the track of hail can be as narrow as a few hundred meters. In this research, radar data were analyzed for severe thunderstorms that produced hail across Tehran, Ahvaz and East Khazar radar stations of the Iran during the 2008–2010. A dataset containing 6 reports of hail that sounding, radar and synoptic stations covering them simultaneously. There are several methods for the detection of hail using single polarizationRadar. The methods with high accuracy of detection hail occurrence and warning threshold have been selected.this method is based on criterion of the Waldvogel hail algorithm that uses the maximum altitude at which a reflectivity of 45dBZ is found in relation to the height of the freezing level. The results show that for height difference greater than 4.5 km, the probability of hail detection is 100%. This value depending on warm and cold climate can be varied up to 1 km.

Fluctuations of density and biomass of polychaetes in four stations at southern Caspian Sea was measured seasonally. Sampling was conducted in February, May, August and November 2006. Benthic samples were collected with a Van Veen Grab sampler from depths of 7 and 20 meters along two transects, from western parts of the coast to Radio Darya area at the east. In the present study, 4 species, 4 genera and 2 families of polychaetes were observed, which were dominated by Parhypania brevispinis. The average maximum density of polychaetes was 3644.2 individuals per square meter (with standard error of 872.1) during Summer in the depth of 7 meters of western transect, while a mean minimum density of 133.3 individuals per square meter (with standard error of 28.9) was observed during Winter in the depth of 7 meters in the same area. Maximum average biomass of polychaetes was 1900 mg per square meter (with standard error of 740) during Spring in the depth of 20 meter of Line 8 area, while the minimum biomass was 30 mg per square meter (standard error was 20) during Winter in the depth of 7 meter in the same area. Generally speaking, the western part of Chalus Coast had more density and biomass as compared with the eastern part.