IMPACT OF SALINITY ON THE CORTISOL, GLUCOSE, CIRCULATING IMMUNOGLOBULIN AND LYSOZYME LEVELS IN BLOOD OF TILAPIA AUREA,

OREOCHROMIS AUREUS

Mohamed Wafeek, Mohamed Abdel Salam and

Amany Abdel Aziz Gharib

Department of
Hatchery and Fish Physiology, Central Laboratory for Aquaculture Research, Agriculture Research Center, Ministry of Agriculture, Egypt.

Corresponding author email: [email protected]

Received 25/ 1/ 2012 Accepted 4/ 3/ 2012

Abstract

In this study, the effect of environmental factor (salinity) on the serum cortisol, glucose immunoglobulin M and lysozyme activities in serum tilapia, Oreochromis aurea were investigated. All treatments, fish was acclimatized in particular environmental conditions for 21 days according to each experiment. Fish reared at different salinities and pH, serum levels of IgM and lysozyme will be increased significantly with high salinity and low pH. The IgM and lysozyme concentrations were significant difference with different salinities levels from 2 up to 8ppt and ranged from 0.215±0.021 to 0.547±0.041 mg/ml and 0.502±0.014 to 0.569±0.018 µg/mg protein at 2 weeks exposure duration respectively. Serum IgM and lysozyme concentrations generally increased with increasing salinity after 2 weeks. These results suggest that the specific immune system of tilapia changes by certain factors in aquatic environment such as salinity and pH, whereas, the cortisol and glucose levels have no significant difference between the different times of the same salinity from the onset up to the end of the experiment, but there are a significant increased with increasing salinity levels.

Keywords: Environmental factor, salinity, pH, serum cortisol, glucose immunoglobulin M, lysozyme, Oreochromis auria.