Effect of temporal increment in salinity of inland saline groundwater on growth performance, survival, metabolic and osmoregulatory responses of juveniles of Labeo rohita (Hamilton, 1822)

Abstract

Conjunctive use of saline groundwater and surface water has been employed in agriculture sector as an operational strategy to preserve water. In the present study, the effect of temporal increment in salinity of inland saline groundwater (ISGW) on growth, survival, physiological, and haemato-biochemical responses of rohu (Labeo rohita) juveniles was examined. The five treatments were assigned with a temporal IGSW salinity increment for 160 days viz., T1 (0.1‰ on daily basis), T2 (0.1‰ for every two days), T3 (0.1‰ for every three days), T4 (0.1‰ for every four days), T5 (0.1‰ for every five days) with C1 (Control 1; 0.0‰) and C2 (Control 2: 4‰). No significant (p > 0.05) difference was found in growth performance between controls and T5, however, the growth rate was determined to be concealed significantly (p < 0.05) from T1 to T4. Both controls and T5 had the highest (100%) survival rates and the lowest was in T1 (5%). In all the treatments except T5, shortening the acclimatization time considerably altered growth and feed utilization in rohu. The hepatic aspartate aminotransferase, alanine aminotransferase, superoxide dismutase activity, and catalase activity in rohu significantly increased with decreasing acclimation period. The activity of Na+/K+-ATPase in gill significantly increased with decreasing acclimation period. Similar to this, with a shorter acclimatization period, serum lysozyme activity decreased significantly. The acclimation period had a substantial impact on serum biochemical and stress parameters (serum cortisol and serum glucose), and these values varied significantly between treatments. The result of the present study indicates that rohu can be successfully cultured in ISGW environments by a temporal increase in salinity level at 7.2‰ (T5) without statistically significant adverse effects on fish performance. In the present study, the temporal increment in salinity levels showed that 80 to 93% survival rates could be achieved in ISGW with salinities up to 12‰ suggesting that unutilised ISGW could be used safely for sustainable aquaculture.