Potential Impact of a Large-Scale Cascade Reservoir on the Spawning Conditions of Critical Species in the Yangtze River, China

Abstract

Dam building and reservoir operations alter the downstream hydrological regime, and as a result, affect the health of the river aquatic ecosystem, particularly for large-scale cascade reservoirs. This study investigated the impact of the Gezhouba Reservoir (GR) and the Three Gorges Reservoir (TGR) on the spawning conditions of two critical taxa, i.e., the endemic four major carps and the endangered Chinese sturgeon in the Yangtze River. We analyzed the flow, sediment, and thermal regime in these two taxa spawning seasons and compared their features between the predam and postdam periods. Our results revealed that the GR and the TGR had altered the frequency distributions of flow, sediment, and water temperature to different degrees, with the impact by the GR on the carps and Chinese sturgeon ranked as water temperature > flow, sediment > water temperature > flow, and the effect of the TGR on these two taxa were ordered as flow > water temperature, sediment > flow > water temperature. For the GR, the satisfying degree of the suitable flow and water temperature of the carps increased, whilst the suitable flow, sediment, and water temperature for the Chinese sturgeon decreased. These changes in TGR showed a significant ascending (descending) trend in the suitable flow (water temperature) for the carps, and a clear decreasing trend in the flow, sediment, and temperature for Chinese sturgeon. Both the TGR and the GR had negative impacts on the spawning of these two taxa in terms of the rising/falling flow characteristics.

Roles of dam and climate change in thermal regime alteration of a large river

“…It is revealed that the impact of climate change has been underestimated in previous studies due to neglecting the meteorological heterogeneity over the catchment (Cai et al 2018, Tao et al 2020, which indicates that the reliance relationships should be used with caution in such large river-reservoir systems. More than one dam is usually constructed on a large river, and their cumulative effects on the downstream RWT and ecosystem have attracted extensive attention (Petesse and Petrere 2012, Cheng et al 2015, Yu et al 2019. This study elaborates the dominance of CDs in the thermal lag upstream of the TGR, and finds that the impact of CDs is rather weak downstream of the TGR, which is in general agreement with the finding of He et al (2020).…”

Impact and prospects of water conservation on fish habitat and advances of ecobiology operation in Yangtze River, China: A review

“…As a result, the low temperature water discharged from the bottom negatively affects the oviposition signal of water-sensitive fish, and ultimately affect the number and quality of oviposition (Caissie, 2006;Ellis and Jones, 2013). Published articles indicate that the water temperature in winter and early spring is highly related to the gonad development of breeding population (Jury, 2012;Yu et al, 2019), reported a significant descending trend for FMCC and CS after TGR operation. Fig.…”

“…Low temperature, cumulative temperature, and relative temperature difference might delay gonad development of fish and spawning of Chinese sturgeon and Four Major Chinese Carp (Yu et al, 2019). Dam construction has also altered the sediment regimes and influenced river geomorphology, morphology, ecosystem health, and stability (Chang et al, 2017; River Basin are now listed in the China Species Red List which is classified into five threatened categories (Wang and Xie, 2009).…”