Heavy metal concentrations in gill and liver tissues of Rutilus kutum and Chelon aurata in the coast of Babolsar, southern Caspian Sea

Heavy metal accumulation in the aquatic ecosystems is a main concern which threats human health. In this study two commercial fish species, Rutilus kutum and Chelon aurata were selected for assessing heavy metal (Cd, Pb, Zn) concentrations in gill and liver tissues at Babolsar’s coast, the southern Caspian Sea, Iran. Babolsar is one of the important fishery stations in the southern Caspian Sea. The results showed that liver tissue of C. aurata significantly accumulated higher concentration of Cd, Pb and Zn compared to that of R. kutum, but these results were not significant for gill tissue. Liver tissue accumulated higher concentration of Cd and Pb compared to gill tissue in C. aurata, but these results were not significant for R. kutum. It is concluded that the liver tissue of C. aurata has higher potential to accumulate heavy metal pollution compared to liver tissue of R. kutu

Ovarian development of Caspian roach, Rutilus caspicus, in southern Caspian Sea: A histological and ultrastructural study

The histology and ultrastructure of the ovarian maturation process in Caspian roach, Rutilus caspicus, was studied. A total 170 female specimens were collected from the Gharasoo River, Bandar Turkmen, the southern Caspian Sea to evaluate its maturation cycle. Based on the results, its ovarian follicle’s development could classified into six stages by distinct characteristics. Minimum and maximum diameter of oocytes were recorded in the chromatin-nucleolus and maturation stages as 56.34±3.74 and 918.83±14.82 µm, respectively. The zona radiata was observed from the cortical alveoli stage and its maximum diameter measured in the secondary vitellogenesis stage as 93.11±23.0 µm. Gonadosomatic index (GSI) reached to its peak in mid-March and its sharp drop in the late April showed its spawning period from late March or early April till the end of April. A positive correlation was found between the GSI and HSI in the vitellogenesis stage. The results also revealed Caspian roach as iteroparous synchronous spawner

Physico-biological modeling of seasonal changes of plankton community in south of Hormoz strait

Planktons are floating microscopic organisms that are confirmed as the primary producers and initial transporters of carbon to the higher levels of food webs. Moreover, planktons have an special importance and status in the habitat of aquatic ecosystems and therefore, their population dynamic assessment is essential in the study of these ecosystems. An extensive range of physical factors viz. nutrients, light, temperature and osmotic stresses influence the growth rate and population of phytoplankton. In the present study, the seasonal dispersion of planktonic populations was modeled in the Strait of Hormuz in 1998, using coupled one- dimensional model (GOTM/NPZD). The results of water column modeling in the summer exhibited the presence of very powerful thermocline and halocline layering in the water column, which maintain till the end of autumn and resulted in hindrance of the water column mix. The model output is indicative of the phytoplankton bloom in the spring followed by zooplankton bloom with a short delay. The zooplankton population bloom peak was at the end of spring. In winter, due to water mixing, temperature and salinity were homogenous in the water column and there were no observed changes in plankton population in studying area According to model output

Seasonal variations of diversity and abundance of the benthic Annelida in coastal sediments of the southern Caspian Sea (Mazandaran-Sari)

In order to investigate seasonal variation of diversity and abundance of Annelida, seasonal sediment sampling was performed on 10 stations with depths of 1, 5, 10 and 20 meters in the coastal area of Sari, Iran in 2015-2016. The results led to the identification of 8 genera and species of Annelida belonging to four families of Polychaeta and two families of Oligochaeta. The highest average annual abundance belonged to Streblospio gynobranchiata and the lowest average belonged to Prenereis sp.  The average frequency of the Annelida was significantly and positively correlated with the percentage of the sand and the total amount of organic matter in sediments. The Shannon-Wiener and Margalef Indices showed that, the Annelida had the highest diversity in summer and the lowest species diversity in winter. The Simpson Heterogeneity Index showed the highest amount in the estuary on winter, and heterogeneity showed reduction with increasing the depth. The value of the brillouin index was increased along with the increase of the depth of the stations. The results of this research indicated that the diversity of Polychaeta and Oligochaeta in the study area is reduced compared to previous studies, while the prevalence of dominant species showed a significant increase

In vitro antibacterial activity of Scenedesmus obtusus (Meyen, 1829) extract

The aim of this study was to assay the antibacterial activity of Scenedesmus obtusus on some pathogenic bacteria. Microalgae S. obtusus were obtained from Algae Bank of Iran, and the methanol, ethyl acetate, chloroform and n-hexane extract of the microalgae were prepared using the maceration method. Bacterial strains were cultured in a solid culture medium, and antibacterial activity of the the different extracts of S. obtusus, were investigated using well diffusion method, and the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), against Staphylococcus aureus, Streptococcus agalactiae as gram-positive bacteria and Escherichia coli and Klebsiella pneumonia as gram-negatives. According to the results, methanolic and ethyl acetate extracts of S. obtusus, showed growth inhibitory effects against all examined bacteria at concentrations of 200, 300 and 400 mg/ml. The chloroform extract was effective only against S. aureus and E. coli, but n-hexane extract had no effect against any of the bacteria. The highest inhibitory effect of S. obtusus extract was observed on methanolic extract against E. coli (16 mm), while the least inhibitory effect belonged to ethyl acetate extract against S. aureus (6.8 mm). The results also showed that the extract of S. obtusus contains antibacterial compounds, and the solvent which used for microalgae extraction significantly affected the antibacterial potential of the extract