THE EFFECTS OF AMBIENT MAGNESIUM CONCENTRATION ON THE EMBRYONIC AND PRELARVAL DEVELOPMENT OF MIRROR CARP (CYPRINUS CARPIO L., 1758)
Metin Çalta and M. Şener Ural
Faculty of Fisheries, University of Firat, 23119-Elazig, Turkey
ABSTRACT. In this study, fertilized mirror carp eggs were allowed to develop in fresh water with various magnesium concentrations (0.05, 0.2 and 2 mg l-1). The percentage of dead (eggs+prelarvae) and deformed prelarvae increased sharply to 94% at an ambient magnesium concentration of 0.05 mg l-1 compared with 22 and 10% at ambient magnesium concentrations of 0.2 mg l-1 and 2.0 mg l-1, respectively. Mirror carp require more than a 0.05 mg l-1 ambient magnesium concentration for survival and successful development during the early life stage. The whole body magnesium and calcium concentrations of the developing prelarvae were dependent on the ambient magnesium concentration. The uptake of magnesium by animals decreased and the uptake of calcium increased with decreasing ambient magnesium concentrations. However, the uptake of the sum of these two divalent ions seemed to be independent of ambient magnesium concentration. This indicates that there is competition between magnesium and calcium for uptake into developing embryos.
Key words: CYPRINUS CARPIO, MIRROR CARP, EMBRYO, HATCHING, MAGNESIUM, CALCIUM