Atrak River region, northeast Iran is a quaternary tectonically active region. There are many geologic structures that they are formed by the collision of the Arabian and Eurasian plates. This area has extended from n...Atrak River region, northeast Iran is a quaternary tectonically active region. There are many geologic structures that they are formed by the collision of the Arabian and Eurasian plates. This area has extended from north east Iran to the of kope dagh zone. The study area is Atrak river basin and it has been divided to 56 Sub-basin for calculation of 6 geomorphic indices. Finally, this region was classified in 4 relative tectonic activity classes.展开更多
The study area has located on Atrak river basin in the Iran-Turkmenistan border zone that is the greatest river on the southeastern margin of Caspian Sea. The study area was divided into 56 sub-basins and then T facto...The study area has located on Atrak river basin in the Iran-Turkmenistan border zone that is the greatest river on the southeastern margin of Caspian Sea. The study area was divided into 56 sub-basins and then T factors were calculated for all streams of the Atrak river. T factor is a geomorphic index for tilting identification by active tectonics. Our results show that, there are low, moderate and high relative tectonic activities levels. Low relative tectonic activities level has been found in sub-basins No. 1, 2, 3, 4, 10, 23, 25, 41 and 51, moderate relative tectonic activities level has been found in sub-basins No. 5, 6, 7, 8, 13, 14, 17, 18, 19, 20, 21, 24, 28, 29, 30, 31, 32, 34, 35, 39, 40, 42, 43, 46, 47,48, 49, 50, 52, 53, 55 and 56 and high relative tectonic activities level has been found in sub-basins No. 9, 11, 12, 15, 16, 22, 26, 27, 33, 36, 37, 38, 44, 45 and 54. Also, most part of the study area has got moderate tectonic activity that it is compatible with its tectonic setting on the Kopetdagh belt in Iran. It is shows that some sub-basins on the western parts of study area that river has got west-east trending, are more active. But, some sub-basins on the eastern parts of study area that river has got northwest-southeast trending, are less active. It means that migration direction of the most streams are toward north and south and the major faults and folds in the western parts of study area caused river tilting be perpendicular to structural trend. This variation along the most important river on the northeastern part of Iran was analyzed for the first time in this research.展开更多
Within the wide distribution of Lenkoran in Iran, populations of the species inhabit variety of habitats. The authors hypothesized that each river may contribute to habitat-specific variation in life history of the fi...Within the wide distribution of Lenkoran in Iran, populations of the species inhabit variety of habitats. The authors hypothesized that each river may contribute to habitat-specific variation in life history of the fish. To test this, a total of 378 specimens of Capoeta capoeta gracilis caught in the Atrak river （northern Iran） from Dec. 2007 to Nov. 2008 were examined for life history attributes. The population has a 5-year life cycle. Weight-length relationship （WLR） was estimated as W = 0.0127TL28981 for males, W = 0.0083TL3998 for females and W = 0.0084TL3942 for the population, being allometric negative for males and positive for females and the population. The VBGF fit to back-calculated size at age data were： Lt = 22.11 （1-e-0.19（t＋135））, Lt = 25.37 （1-e-0.18（t＋125）） and Lt = 24.92 （1-e-018（1＋122）） for males, females and sexes combined respectively. Sex ratio was significant from the parity, females dominated. The reproductive season, evaluated from GSI, extended from Apr. to July, with the highest peak in May for males and in Apr. for females. The absolute fecundity ranged between 458-5,743 eggs with a mean of 1,375.06 eggs. Fecundity relative to total weight fluctuated from 14.90 to 132.58, with a mean value of 48.79 eggs·g-1. The diameter of oocytes ranged from 0.53 to 2.40 mm with a mean value of 1.46. The life history patterns of C. c. gracilis in the considered population imply that the many population characteristics of this species in the river differ markedly from those of other rivers of its range distribution in northern Iran. Probably, respond to environmental characteristics to improve fitness locally is the more suitable choice for differentiated life history strategies of the species in the river.展开更多
文摘Atrak River region, northeast Iran is a quaternary tectonically active region. There are many geologic structures that they are formed by the collision of the Arabian and Eurasian plates. This area has extended from north east Iran to the of kope dagh zone. The study area is Atrak river basin and it has been divided to 56 Sub-basin for calculation of 6 geomorphic indices. Finally, this region was classified in 4 relative tectonic activity classes.
文摘The study area has located on Atrak river basin in the Iran-Turkmenistan border zone that is the greatest river on the southeastern margin of Caspian Sea. The study area was divided into 56 sub-basins and then T factors were calculated for all streams of the Atrak river. T factor is a geomorphic index for tilting identification by active tectonics. Our results show that, there are low, moderate and high relative tectonic activities levels. Low relative tectonic activities level has been found in sub-basins No. 1, 2, 3, 4, 10, 23, 25, 41 and 51, moderate relative tectonic activities level has been found in sub-basins No. 5, 6, 7, 8, 13, 14, 17, 18, 19, 20, 21, 24, 28, 29, 30, 31, 32, 34, 35, 39, 40, 42, 43, 46, 47,48, 49, 50, 52, 53, 55 and 56 and high relative tectonic activities level has been found in sub-basins No. 9, 11, 12, 15, 16, 22, 26, 27, 33, 36, 37, 38, 44, 45 and 54. Also, most part of the study area has got moderate tectonic activity that it is compatible with its tectonic setting on the Kopetdagh belt in Iran. It is shows that some sub-basins on the western parts of study area that river has got west-east trending, are more active. But, some sub-basins on the eastern parts of study area that river has got northwest-southeast trending, are less active. It means that migration direction of the most streams are toward north and south and the major faults and folds in the western parts of study area caused river tilting be perpendicular to structural trend. This variation along the most important river on the northeastern part of Iran was analyzed for the first time in this research.
文摘Within the wide distribution of Lenkoran in Iran, populations of the species inhabit variety of habitats. The authors hypothesized that each river may contribute to habitat-specific variation in life history of the fish. To test this, a total of 378 specimens of Capoeta capoeta gracilis caught in the Atrak river （northern Iran） from Dec. 2007 to Nov. 2008 were examined for life history attributes. The population has a 5-year life cycle. Weight-length relationship （WLR） was estimated as W = 0.0127TL28981 for males, W = 0.0083TL3998 for females and W = 0.0084TL3942 for the population, being allometric negative for males and positive for females and the population. The VBGF fit to back-calculated size at age data were： Lt = 22.11 （1-e-0.19（t＋135））, Lt = 25.37 （1-e-0.18（t＋125）） and Lt = 24.92 （1-e-018（1＋122）） for males, females and sexes combined respectively. Sex ratio was significant from the parity, females dominated. The reproductive season, evaluated from GSI, extended from Apr. to July, with the highest peak in May for males and in Apr. for females. The absolute fecundity ranged between 458-5,743 eggs with a mean of 1,375.06 eggs. Fecundity relative to total weight fluctuated from 14.90 to 132.58, with a mean value of 48.79 eggs·g-1. The diameter of oocytes ranged from 0.53 to 2.40 mm with a mean value of 1.46. The life history patterns of C. c. gracilis in the considered population imply that the many population characteristics of this species in the river differ markedly from those of other rivers of its range distribution in northern Iran. Probably, respond to environmental characteristics to improve fitness locally is the more suitable choice for differentiated life history strategies of the species in the river.
