اثر شوري هاي مختلف بر ميزان املاح، فشار اسمزي، آب بافت بدن، سلولهاي كلرايد آبششي و درصد تلفات بچه ماهي سفيد (Rutilus frisii kutum Kamensky 1901)

Effect of different salinity on ions, osmolarity, water concentration of body tissue, gill chloride cells and mortality percentage of juveniles of Caspian roach

Changes of ions (Na", CI", K+), osmolarity and water concentration of body tissue, size and number of gill chloride cells as well as mortality percentage of the juveniles Caspian roaches in weight groups of 0.2, 0.5 & lg water saliny stress were studied. The salinities tested were 0 (fesh water), 7, 12.5 & 16g/lit and the assessments were completed 0, 12, 24, 48 & 72 hours after exposure. Results showed that ions and osmolarity of juveniles weighting 0.2 & 0.5g in salinities of 0 up to 12.5g/lit increased significantly during the first 12 hours (P<0.03). These values then showed downward trend to the values recorded for fresh water. Water concentration of body tissue reached the minimum mean value in 12 hours (P<0.05) in salinity of 12.5 g/lit and then showed upward trend to the value obtained for freshwater. Ions ana osmolarity of body tissue of the juveniles increased and water concentration of body tissue decreased significant after the first 12 hours of transferring into salinity of 16g/lit (P<0.05). Weight changes in juveniles of lg in salinities of 0 up to 16g/lit was similar to juveniles of 0.2 & 0.5g in salinities of 0 up to 12.5g/lit and the maximum mean values of ions and osmolarity and the minimum value of water concentration body tissue in 16g/lit salinity in hour 12 (P<0.05). Size and number of gill chloride cells of juveniles weighting 0.2 & 0.5g in salinities of 0 up to 12.5g/lit increased significantly during the first 12 hours of exposure (P<0.05) and reached the maximum mean values in 12.5g/lit salinity 12 & 24 hours after exposure, respectively (P<0.05) and showed invisible changes up to the end of the test. Size and number of choride cells of the juveniles increased after the first 12 hours of transferring into salinity of 16g/lit (P0.05). Changes of the indices in juveniles weighting lg in salinities of u up to 16g/lit was similar to juveniles of 0.2 & 0.5g kept in salinities of 0 up to 12.5g/lit and the maximum values was in 12 and 24 hours after exposure, respectively (P<0.05). Ions and osmolarity of body tissue and size and number of chloride cells increased significantly with increase of salinity and weight and water salinity and water concentration of body tissue decreased significantly with increase in water salinity and increased in fish weight (P<0.05). Juveniles weighting 0.2 up to 1 g showed no mortality in salinities of 0 & 7g/lit during the test. Mortality of the juveniles weighting 0.2, 0.5 and 1 g/lit increased during the first 12 hours and became constant to the end of the test. Mortality of juveniles weighting 0.2 & 0.5g in salinity of 16g/lit was similar to that of the juveniles weighting 0.2 & 0.5f in salinity of 12.5g/fit. Mortality of the juveniles increased significantly with increase of salinity and decreased with increase of weight (P<0.05).