Tolerance of Prenant's Schizothoracin Schizothorax prenanti to Total Dissolved Gas Supersaturated Water at Varying Temperature

Abstract

AbstractHydropower development changes the temporal and spatial distribution of water temperature and causes total dissolved gas (TDG) supersaturation downstream of dams. We conducted laboratory experiments to determine the effects of TDG supersaturation on Prenant's Schizothoracin Schizothorax prenanti at varying water temperatures. The fish were exposed to 120, 130, 135, and 140% TDG‐supersaturated water at different water temperatures within the range of 12–24°C for 96 h. Survival rate of Prenant's Schizothoracins declined with increasing TDG saturation. At 120% TDG, the final survival rate of fish was over 50% at the different temperatures. However, when the TDG level increased to 130% or above, the survival rate decreased sharply. The median survival time of fish ranged from 5.22 to 18.62 h when exposed to 130% TDG, ranged from 2.41 to 9.41 h at 135% TDG, and was less than 5 h at 140% TDG. Under 120% TDG conditions, fish survival rate was not significantly different among water temperatures (12–24°C). However, when the TDG level was 130%, the survival rate of the fish declined with increasing water temperature. In 135% and 140% TDG‐supersaturated water, the survival time of the fish was longer at 16°C than at other temperatures.