Tolerance and Avoidance Characteristics of Prenant's Schizothoracin Schizothorax prenanti to Total Dissolved Gas Supersaturated Water

Abstract

When water is allowed to spill over a hydroelectric dam, the intense aeration and pressure in the deep plunge‐pool produced by the high‐volume discharge generates water supersaturated with total dissolved gases (TDGs) in areas downstream from the dam, which can cause gas bubble disease (GBD) in fish and threaten their survival. Experiments were conducted to measure the acute lethality, intermittent exposure, horizontal avoidance, and vertical avoidance of Prenant's Schizothoracin Schizothorax prenanti related to TDG supersaturation. The fish were placed in different tanks containing TDG‐supersaturated water at a maximum water depth of 35 cm, and the resulting median lethal times (LT50) determined for the fish were 23.88, 9.66, 8.74, 8.03, 4.61, 3.48, and 2.81 h when the TDG supersaturation levels were 120, 125, 130, 135, 140, 145, and 150%, respectively. The LT50 values of the fish in continuous exposure conditions were not significantly different from the LT50 values of fish subjected to intermittent exposure (F = 2.72, df = 9,10, P = 0.07). In all of the avoidance experiments, Prenant's Schizothoracin exhibited varying degrees of horizontal escape from and strong vertical avoidance of TDG‐supersaturated water. These results provide important information that can be used in operational processes at hydropower stations in China and contribute fundamental data for the establishment of water‐related environmental standards for this and similar species. Received November 1, 2014; accepted May 8, 2015

Hatching rate of Chinese sucker ( Myxocyprinus asiaticus Bleeker) eggs exposed to total dissolved gas (TDG) supersaturation and the tolerance of juveniles to the interaction of TDG supersaturation and suspended sediment

“…The LT 50 values of these fish were all above 15 hr at 125% TDG and exceeded 9 hr at 130% TDG. Relative studies of endemic species in the Yangtze River (e.g., rock carp, prenant's schizothoracin and silver carp) have been performed through laboratory experiments (Cao et al, ; Huang et al, ; Wang et al, ). Table shows the LT 50 values of these three species and Chinese sucker at TDG supersaturation levels of 125%, 130%, 135% and 140%.…”

“…In China, fish downstream of dams die from GBD during flood discharges (Tan, Ni, Zheng, Li, & Li, ). Moreover, some laboratory experiments were carried out to assess the effect of TDG supersaturation on fish, such as rock carp ( Procypris rabaudi ), Chinese sucker, silver carp ( Hypophthalmichthys molitrix ) and prenant's schizothoracin ( Schizothorax prenanti ) (Cao, Liang, Tuo, Li, & Li, ; Chen et al, ; Huang, Li, Du, & Li, ; Wang, Li, Li, Li, & Deng, ). Liang, Li, Li, and Tuo () first investigated the relationship between hatching rate and TDG levels.…”

In situ study on the impact of total dissolved gas supersaturation on endemic fish in the Upper Yangtze River

“…The mortality of David's schizothoracin ( Schizothorax davidi ) fry did not exceed 50% when they were exposed to water with TDG supersaturation levels less than 125%, and their LT 50 reached 35 hr when they were exposed to waters with TDG supersaturation levels of 130% (Liang et al, ). The LT 50 of Prenant's schizothoracin ( Schizothorax prenanti ) with a weight less than 10 g was approximately 20 hr when exposed to water with a TDG supersaturation level of 120% (Wang, Li, et al, ). Moreover, Chinese suckers ( Myxocyprinus asiaticus ) with a weight of approximately 40 g could survive in water with a TDG supersaturation level of 125% for 43 hr (Chen et al, ).…”

“…Qu, Li, Li, Li, and Deng () found that outflow from the Three Gorges Dam caused the TDG supersaturation level to reach 143% and that only 17% of the supersaturated TDG had been released 600 km downstream of the dam. Previous studies have indicated that fish can be severely compromised when the TDG supersaturation level reaches 120% (Geist, Linley, Cullinan, & Deng, ; Huang, Li, Du, & Li, ; Smiley, Drawbridge, Okihiro, & Kaufmann, ; Wang, Li, Li, Li, & Deng, ; Wang, Liang, Tuo, Li, & Hodges, ). TDG supersaturation is associated with hydrostatic pressure, and when the TDG concentration in the water is constant, the supersaturation level will decrease with increasing water depth (Weitkamp, ).…”

“…Studies have been performed in recent years to evaluate the influence of TDG supersaturation on fish inhabiting the upper Yangtze River to address the problems caused by the construction of high dams (Chen et al, ; Huang et al, ; Wang, Li, et al, ; Wang, Liang, et al, ). However, many of these studies were conducted under controlled laboratory conditions, and few studies have been conducted in the upper Yangtze River, which is regulated by dam operations.…”