Land use and river-lake connectivity: Biodiversity determinants of lake ecosystems

Lake ecosystems confront escalating challenges to their stability and resilience,most intuitively leading to biodiversity loss,necessitating effective preservation strategies to safeguard aquatic environments.However,the complexity of ecological processes governing lake biodiversity under multi-stressor interactions remains an ongoing concern,primarily due to insufficient long-term bioindicator data,particularly concerning macroinvertebrate biodiversity.Here we utilize a unique,continuous,and in situ biomonitoring dataset spanning from 2011 to 2019 to investigate the spatio-temporal variation of macroinvertebrate communities.We assess the impact of four crucial environmental parameters on Lake Dongting and Lake Taihu,i.e.,water quality,hydrology,climate change,and land use.These two systems are representative of lakes with Yangtze-connected and disconnected subtropical floodplains in China.We find an alarming trend of declining taxonomic and functional diversities among macroinvertebrate communities despite improvements in water quality.Primary contributing factors to this decline include persistent anthropogenic pressures,particularly alterations in human land use around the lakes,including intensified nutrient loads and reduced habitat heterogeneity.Notably,river-lake connectivity is pivotal in shaping differential responses to multiple stressors.Our results highlight a strong correlation between biodiversity alterations and land use within a 2e5 km radius and 0.05e2.5 km from the shorelines of Lakes Dongting and Taihu,respectively.These findings highlight the importance of implementing land buffer zones with specific spatial scales to enhance taxonomic and functional diversity,securing essential ecosystem services and enhancing the resilience of crucial lake ecosystems.

Determination of water environment standards based on water quality criteria in China:Limitations and feasibilities

There is a need to formulate water environment standards（WESs） from the current water quality criteria（WQC） in China.To this end,we briefly summarize typical mechanisms applied in several countries with longer histories of developing WESs,and three limitations to formulating WESs in China were identified.After analyzing the feasibility factors including economic development,scientific support capability and environmental policies,we realized that China is still not ready for a complete change from its current nation-wide unified WES system to a local-standard-based system.Thus,we proposed a framework for transformation from WQC to WESs in China.The framework consists of three parts,including responsibilities,processes and policies.The responsibilities include research authorization,development of guidelines,and collection of information,at both national and local levels;the processes include four steps and an impact factor system to establish water quality standards;and the policies include seven specific proposals.