تأثير النقل المفاجئ والتدريجي لمياه البحر على المحتوي المائي لبعض أنسجة سمكة البلطي الأخضر zillii Tilapia المجمعة من المياه العذبة

Abstract

Effects of abrupt and gradual transfer to sea water on Euryhaline freshwater Tilapia zillii were studied. Survival rates at different salinity medias were recorded. Tilapia zillii was able to tolerate modest salinity concentrations up to 27g/l upon sudden exposure. However, full strength sea water (36.00 g/l salinity) appeared lethal. But, gradual transfer to such salinity (36.00 g/l salinity) was useful in raising the survival rate in such concentration to 100%. Selected tissues , including gills, liver and muscles of Tilapia zillii exhibited reduction in water contents record following abrupt transfer of fish to all hypertonic media. In the gradual transfer, the non-significant differences in tissue water between different experimental groups, lead to the conclusion that Tilapia zillii has well-adapted to the new-habitat by activating water-regulatory compensation (Homeostasis).