Original ArticleMacrobenthos functional groups as indicators of ecological restoration in the northern part of China's Yellow River Delta Wetlands

- We studied the effects of freshwater releases on restoration of delta wetlands.
- Freshwater releases improved abundance, biomass, and biodiversity of macrobenthos functional groups.
- The abundance-biomass comparison curves showed strong disturbance and the macrobenthos community structure was fragile during freshwater releases.
- The restoration area had high carbon and moisture, but low salinity and grain size.

Freshwater releases to restore degraded wetlands are a globally recognized way to maintain the biodiversity and enhance the health of wetland ecosystems. To better understand the efficacy of freshwater releases in the northern part of China's Yellow River Delta Wetlands, we used macrobenthos functional groups in spring (before freshwater releases), summer (during), and autumn (after) as indicators of the ecological responses. We also created abundance-biomass comparison curves and analyzed secondary production of each trophic level to evaluate the magnitude of the disturbance of the macrobenthos community. Abundance, biomass, and biodiversity of macrobenthos functional groups generally improved after the freshwater releases. In contrast with an intertidal (reference) area, the macrobenthos community in the ecological restoration area tended to be freshwater species. In the ecological restoration area, strong and moderate ecological disturbance of the macrobenthos community was evident during and after freshwater releases because the abundance curve remained above the biomass curve. Secondary production was in the order trophic level III > II ≅ IV in the summer, which indicates fragility of the macrobenthos community. The ecological restoration area had the highest sediment total organic carbon and moisture contents, but the lowest salinity and median particle size, and these differences were statistically significant. Our results suggest that adaptive freshwater releases, including a long-term freshwater release plan that more closely emulates natural flows and increasing the efficiency of freshwater utilization, will be necessary to achieve sustainable management of the wetland's ecosystem and reduce the disturbance caused by the freshwater releases.