Acclimatization of fish to the higher calcium levels in the water environment

Abstract

It is established that calcium concentration changes (variations) in the water environment significantly influence its intake and distribution in tissues and organs of hydrobionts. The decrease in calcium concentration in water from 100 to 60 mg.L-1 significantly reduces its content in fish liver. In the gills glandular apparatus of fish acclimated to the environment with lower calcium level (in comparison with control one), its concentration on the first day of the acclimation period slightly exceeded the initial level, thus testifying to its possible excretion of endogenous calcium by gills. The increase of calcium excretion through the renal and digestive systems in fish acclimates to the higher water level, and specific changes in phosphates excretion dynamics accompany oral intake. Long keeping fish in water with 100 mg.L-1 calcium is accompanied by the increase of total phosphorus in urine (by 2 – 2.5 times), and its day excretion increases by 1.9 – 2.4 times. During fish acclimation to higher calcium levels in the water environment, the excretion of total phosphorus with faecal matter increases. The increase of calcium in the water environment to 100 mg.L-1 leads to a temporary increase in total phosphorus excretion with faecal issues. The rise in cation concentration to 200 mg.L-1  increases significantly during long-time fish stay in such an environment.