علوم زیستی دریا
Abdolsamad Dehghan; Ahmad Savari; Tooraj Valinassab; babak Doustshenas; Parvin Sadeghi
Abstract
To study the effects of monsoon on the richness and seasonal changes in the density of crabs in the intertidal area of the southern coast of Sistan and Balouchestan province, sampling was carried out in 2013 (based on the intensity of the monsoon) in three seasons: pre-monsoon, monsoon and post-monsoon ...
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To study the effects of monsoon on the richness and seasonal changes in the density of crabs in the intertidal area of the southern coast of Sistan and Balouchestan province, sampling was carried out in 2013 (based on the intensity of the monsoon) in three seasons: pre-monsoon, monsoon and post-monsoon using quadrats (Dimensions 50x50 cm and depth 10 cm), in 5 different stations. During the research, organic matter, salinity and temperature were also measured. Altogether, in this study, 17 species belonging to 10 families and 15 genera were identified. Based on the two-way ANOVA analysis results, a significant difference in brachyuran crab density and diversity was observed between the three seasons. The lowest species richness and density between the three seasons were recorded during the monsoon due to environmental stress. On the other hand, due to the presence of favorable environmental conditions for crabs, the highest density and species richness were observed in the prior and post-monsoon seasons. The statistical comparison of density in different stations showed that due to the significant relationship between density, grain size, and other environmental conditions, Jazireh Krahang and Gowater stations have the highest amount of TOM throughout the year, the presence of mud substrate and mangrove ecosystem has the highest species richness and density. In contrast, the lowest density has been recorded at Tiss and Bris. Monsoons can affect the ecology of living organisms differently. Totally, Monsoons can cause a decrease in the density and abundance of crabs during monsoon season in the intertidal zone due to their extensive effects on environmental conditions such as the content of organic matter and substrate conditions.
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.