SEASONAL CHANGES IN WATER QUALITY AND THEIR EFFECTS ON CORTISOL AND LIPID CONTENTS IN SERUM AND TISSUE OF GILTHEAD SEA BREAM (SPARUS AURATA) CULTURED IN EARTHEN PONDS

Mohammed Wafeek1 and Mona Hamed Ahmed2

1Fish Physiology and hatchery Department. 2Limnology Department Central Laboratory for Aquaculture Research, Agriculture Research Center, Ministry of Agriculture, Egypt.

Corresponding email: [email protected]

Received 2/ 11/ 2011 Accepted 25/ 12/ 2011

Abstract

The study was undertaken on sea bream fish to show the different water parameters (water temperature oC, dissolved oxygen mg/l, salinity ppt, pH, total ammonia, toxic ammonia, ortho phosphate, total alkalinity mg/l, and chlorophyll a. Phytoplankton org. /l and zooplankton org. /l) on some physiological measurements (glucose mg/dl, cortisol ng/ml, total protein g/dl, lipid composition in tissue and blood) and growth performance during the different seasons of culture. Water source was supplied from Manzala Lake which has a variable salinity. The main important factors in water quality were, salinity ranged from 25.5 to 36.5 ppt; temperature ranged from 16.1 to 31.1 oC, dissolved oxygen ranged from 4.1 to 7.6 mg/l and ortho phosphate from 0.11 to 0.36 mg/l from season to another. All water quality parameters in the suitable limits for growth expect water nutrients. The main important physiological factor was glucose (63.5:99.6 mg/dl) and cortisol (85.3:122.3 ng/ml). Serum cholesterol and triglycerides were recorded in different seasons and ranged from 141.2±4.6 to 120.5±3.2 mg/dl and 78.8±2.7 to 61.2±2.8 mg/dl respectively. Serum some electrolytes (sodium and potassium mmol/l) were measured. Also, hematological parameters; hemoglobin, erythrocyte count and hematocrite were recorded. The interaction between salinity and temperature affect many metabolic parameters in the tissues assessed, especially in liver and muscle, suggesting that such interaction is inducing an important metabolic cost for the animal. It was reflected on growth and some physiological parameters of Gilthead Sea bream. The fish performance is affect by poor water quality. Sea bream had low daily growth compared as fresh water fish. The growth performance of Sea bream increased during summer and autumn. So the water quality and physiological states have direct effect on Sea bream growth performance.

Keywords: water quality; Sea bream; serum; cortisol ; glucose; cholesterol; triglycerides, Hb, RBCs; PCV, growth performance, final weight and weight gain.