| Popis: |
This study has carried out on five earth ponds of Litopenaeus vannamei shrimps investigation and Mahan Siraf farm s which located at Helleh site in the Bushehr province from may 2007. main objectives’ were: (1) Measurements of quality factors in water and sediment, Planktons and benthoses, (2) quality factors’ effects on growth and survival of Litopenaeus vannamei. With respect the time of shrimp stocking and harvesting, the frequencies of water and sediment sampling were done per 10 day and once per month, respectively. both sediment sampling of the pond beds have done before and after harvesting. The measured factors in the water ponds were: pH, salinity, dissolved oxygen, transparency, temperature (Twice a day in the morning and the afternoon), chlorophyll-a, nitrate, nitrite, orthophosphate, iron, biochemical oxygen demand, TSS, TDS, Planktons. The parameters (pH, total organic matter, iron) were measured in sediment. The measurement of grain size has done in two times (before and after harvesting). Independent variables including nitrate, Ammonia, orthophosphate, iron and chlorophyll-a had significant correlations with shrimp weights as dependent variable. Nitrate showed the highest correlation with the shrimp weights (r=0.921). overall correlation of fifth most important factors with the shrimp weights, namely nitrate, orthophosphate, Ammonia, iron and chlorophyll-a was estimated to r=0.999. The results show low concentration of the essential nutrient such as phosphate and nitrate, high concentration of ammonia, undesirable’s transparency, and a great amount of clay in pond beds. On the basis of above description, required to renewing management in fertilizing, feedings, liming qualities of the bed. |
