Widespread declines in water salinity of the endorheic Tibetan Plateau lakes

Abstract

The Tibetan Plateau (TP) hosts more than one thousand lakes (>1km2) in its endorheic basins. The changing climate in recent decades has led to significant modifications in the endorheic hydrologic system. Most TP lakes experienced dramatically expanding areas, rising water levels, and increasing storage, which inevitably influenced the lake salinity. This study provides a regional-scale investigation of water salinity changes of the TP lakes (for 83 lakes with two-epoch salinity records, among the approximately 160 lakes >50km2) by synthesizing multi-source data around the 1970s and 2010s. Our results reveal lake salinity has considerably declined for most expanding lakes across the endorheic basins. The mean salinity of 62 terminal lakes dropped from 92.76g/L to 42.00g/L during the 1970s-2010s, in contrast to the slight variations (3.42g/L to 1.48g/L) of the 21 exorheic or upstream lakes. As a result, many hypersaline lakes have become polysaline or oligosaline lakes, such as Cedo Caka, Norma Co, etc. In particular, some large lakes (e.g., Siling Co, “Twin Lakes”, and Ayakkum Lake) also experienced significant drops in water salinity, with the exceptional cases for Nam Co and Qinghai Lake probably due to the relatively low ratios of increased water mass to their net storages. The widespread declining water salinities could greatly influence bacterial richness, diversity, and evenness, and affect the aquatic carbon cycle and utilization in the high-altitude endorheic lakes. More attention should be paid on understanding the saline lake ecosystem evolution and the regional carbon cycle in response to changing water salinity of the TP lakes.

Alpine Extremophytes in Evolutionary Turmoil: Complex Diversification Patterns and Demographic Responses of a Halophilic Grass in a Central Asian Biodiversity Hotspot

“…Species dependent on limited habitat resources could be more fragile to environmental disturbances and prone to genetic erosion or even extinction ( Aguilar et al 2008 ; Haddad et al 2015 ; Crooks et al 2017 ). Therefore, alpine extremophiles may particularly experience abrupt ecological responses due to their heavy reliance on distinct and dynamically changing niches ( James et al 2005 ; Song et al 2022 ; Sagwal et al 2023 ). On the other hand, effective mechanisms related to stress response regulations and primary metabolic processes under limited resources ( Eshel et al 2021 ; Guo et al 2021 ) could give the extremophiles the ability to survive adverse environmental changes projected for the future ( Uzilday and Ganie 2023 ).…”

Salinity as a key factor affecting viral activity and life strategies in alpine lakes

“…In recent decades, Tibetan lakes have undergone substantial alterations due to the increased wetting climate and glacial meltwater supply (Ke et al 2022). The expanding lake areas, rising water levels, and increased storage in most lakes have led to a significant decline in lake salinity (Song et al 2013; Luo et al 2021; Song et al 2022). Our findings highlight salinity as a pivotal factor influencing viral abundance and life strategies, suggesting that the evolving lake conditions, influenced by climate change, may instigate variations in viral activities.…”

“…Our findings highlight salinity as a pivotal factor influencing viral abundance and life strategies, suggesting that the evolving lake conditions, influenced by climate change, may instigate variations in viral activities. The decreasing salinity in Tibetan lake waters could potential transform hypersaline lakes into polysaline or oligosaline lakes (Song et al 2022), significantly impacting viral activity, life strategies, and consequently, the viral-mediated carbon cycle in Tibetan lakes.…”

Response of phytoplankton composition to environmental stressors under humidification in three alpine lakes on the Qinghai-Tibet Plateau, China

“…However, hypersaline lakes remain under-studied compared to their freshwater counterparts ( Williams et al, 1990 ; Williams, 1998 ; Williams, 2002 ; Larson and Belovsky, 2013 ). The lakes on Tibetan Plateau may undergo a decline in salinity since the balance of precipitation and evaporation was broken as reflected by the expansion of the surface water in many alpine lakes under climate change ( Song et al, 2022 ). A study by Li et al (2021) found that salinity was the dominant factor controlling phytoplankton community abundance and biomass in lake systems on the Qinghai - Tibet Plateau.…”