“Peak reduction and trough filling”: A promising strategy for restoring a degraded coastal lagoon from ecological imbalance to stability through integrated biomanipulation

As anthropogenic pressures intensify, aquatic ecosystems experience biodiversity loss and trophic imbalances that compromise their stability and resilience. Biomanipulation offers a promising avenue for ecological restoration, but its long-term effectiveness remains understudied. Using Yundang Lagoon as a case study, this research employed Ecopath with Ecosim modeling and a “peak reduction and trough filling” strategy to explore trophic structure and ecosystem function. Ten biomanipulation scenarios were tested through Ecosim simulations and trophic level spectrum analyses. In 2008, ecosystem maturity was relatively low, with persistent imbalances characterized by most energy flow being confined to lower trophic levels and a transfer efficiency of only 3.93 %. A comprehensive biomanipulation approach that reduces high-biomass functional groups and supplements low-biomass groups produced the greatest increases in transfer efficiency, which rose to 10.99 % after three rounds of intervention. Gains in the ecosystem's energy transfer efficiency typically peak in the third year following each intervention, and although the rate of improvement diminishes over time, the lagoon continues to progress toward a more mature and stable state. These findings can inspire ongoing management efforts in Yundang Lagoon and underscore the potential of repeated, targeted biomanipulation for restoring similarly degraded coastal lagoon ecosystems.