Confronting challenges of managing degraded lake ecosystems in the Anthropocene, exemplified from the Yangtze River Basin in China

Abstract

Abstract Freshwater lake ecosystems have supported livelihoods for millennia. Yet, most lakes worldwide today are suffering severe degradation in response to anthropogenic pressures. Scientists and managers are facing pressing challenges to define safe operating space for successful lake management into the future. Achieving these goals requires a clear understanding of nonlinear trajectories of ecosystems response to changes in multiple interacting drivers at multi-decadal scales. Based on a synthesis and analysis of published paleo-environmental records, this paper shows that many lakes in the Middle and Lower Yangtze River Basin (MLYB) have undergone abrupt ecological shifts during the 1950s–1980s. The causes for these significant changes were multiple accumulating drivers acting together through time including climate change, land reclamation, agricultural intensification, and industrialization. This paper also explored the potential of defining the Anthropocene baseline for proper restoration and management in the MYLB based on paleo-environmental records. That is, we reveal that a return to the pre-1900s historical condition is no longer possible for many degraded lakes due to both socioeconomic and ecological constraints. For some severely degraded lakes with high sedimentation rates, restoration to the 1970s and 1980s levels within the historical range of variability might be more realistic, though constrained by socioeconomic limitations on reducing anthropogenic drivers. Management actions can still guide other lakes with low or moderate levels of sedimentation toward their pre-1900s conditions. This analysis is the first of its kind in illustrating within the MYLB that long-term paleo-environmental records can have useful applications in identifying the restoration targets in degraded aquatic ecosystems. It also suggests a pathway for potentially improving the resilience of such social-ecological systems toward sustainability.