علوم زیستی دریا
Halimeh Bameri; Mehran Loghmani; Gilan Attaran Fariman
Abstract
Polychaetes are important in determining the environmental status of seabed and their role in the food chain. Sampling of sediments in three areas of Beris, Ramin and Pasabandar was performed at 10 stations in the north of the Makoran Sea by Garb van-veen during three periods of pre-monsoon, monsoon, ...
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Polychaetes are important in determining the environmental status of seabed and their role in the food chain. Sampling of sediments in three areas of Beris, Ramin and Pasabandar was performed at 10 stations in the north of the Makoran Sea by Garb van-veen during three periods of pre-monsoon, monsoon, and post-monsoon winter with recordings of chemical physical parameters from November to March 2016. In the study identified 18 families of polychaetes communities it was found that the highest density in Monson period and in Post-Monsoon with 4364.67 ± 570 ind/m2 and the lowest density in Post-Manson period in Roman region with 225.33 ± 89 ind/m2. In the pasaBandar area, the highest percentages belonged to the families Spionidae, Maldanidae and Cirratulidae, and to the families of Nephtydae, Phyllodocidae and Cirratulidae and to the Ramin family's Orbiniidae, Maldanidae and Cirratulidae. One-way ANOVA showed significant differences between stations and time periods (P <0.05). The highest densities of the polychaetes were estimated in terms of the period of Monsoon> Pre-Monsoon> Post-Monsoon period, respectively. Results of correlation between polychaete density and environmental factors of grain size sediment and TOM in pre-monsoon period showed a positive and significant correlation. There was no positive and significant correlation with environmental factors in monsoon period (P <0.05), but there was a significant positive correlation with grain size in post-monsoon period (p<0.05). The results showed that winter monsoon causes significant changes in the populations of the studied areas and the increase in density in monsoon can be due to the change of the currents direction and consequent increase of nutrient load in the area.
علوم زیستی دریا
Noormohammad Safaei; Mehran Loghmani; Parvin Sadeghi
Abstract
The Makoran Sea is been influencing by the summer and winter monsoon currents, and this phenomenon is a natural stressor for species inhabiting the aquatic ecosystem, including bivalve molluscs. In the current study, the effect of winter monsoon on the sub-tidal bivalve densities of the northern coast ...
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The Makoran Sea is been influencing by the summer and winter monsoon currents, and this phenomenon is a natural stressor for species inhabiting the aquatic ecosystem, including bivalve molluscs. In the current study, the effect of winter monsoon on the sub-tidal bivalve densities of the northern coast of Makoran were evaluated. Sampling of sediments were conducted from three regions of Ramin (3 stations), Beris (3 stations) and Pasabandar. Physical chemical parameters of transparency, salinity, acidity, temperature, organic matter, and grain size of each station were also obtained to investigate their relationship with density, which among the factors, only temperature, were significantly lower in the monsoon and pre-monsoon periods. In this study, 10 species of bivalves were identified, according to which Donax scalpellum with 13.37% had the highest and Trisidos tortuosa with 3.98% had the least frequency. The population of bivalves was calculated after Monsoon, with a frequency of 46.17% (mean 713 ±23.14 m2), pre-Manson, with 27% (mean of 413 ± 25.12 m2) and Monsoon, with 26% abundance. (413±13.34 m2). The pasabandar was (including stations 7, 8, 9 and 10), with an average density of 63±28.2 persons / m2 having the highest density in comparison to Beris (43±17.7) and Ramin (44±19.37). There was a significant difference between the stations. There was no significant positive correlation between silt and sand and temperature with density but no significant relationship between other environmental factors and organic matter with density. In general, it can be said that various factors are considered as parameters controlling the abundance and expansion of bivalve communities of different study areas and stations in the northern coastal waters of Makoran, including It is possible to name the factors of temperature, particle size and type of substrate, organic matter and nutrients, monsoon flows that have the most influence on the density of bivalve organisms.