Restoration and stabilization of benthic communities in Lake Shihwa: Effects of a tidal power plant

초록

As restoration projects focused on rehabilitating degraded ecosystems grow in importance, evaluating their success is critical. We assessed the impact of operating a tidal power plant, established for restoration of the polluted Lake Shihwa, South Korea, on the marine environment and benthic communities. Prior to the plant's implementation, the species richness of benthic macroinvertebrates in Lake Shihwa was below 10 species per 0.1 m2, and the ecosystem was characterized by instability and high variability. However, post-implementation, stable communities with increased species richness, abundance, and biomass developed. These communities changed to resemble those of the outer sea by 2012, indicating rapid recovery. A significant increase in salinity was observed in Lake Shihwa, and recurring summer hypoxia events were eliminated. Also, chemical oxygen demand (COD) levels and sediment organic carbon contents were markedly reduced. Although no deterioration in water quality was observed in the outer sea, the benthic communities at the study sites closest to the tidal power plant experienced initial degradation and recoveries immediately after the plant began operating. Our findings show that restoring seawater circulation was vital for this ecosystem's recovery. However, since 2017, COD levels in both Lake Shihwa and the outer sea have been rising. In 2022, a significant increase in the community indices of benthic communities in Lake Shihwa was noted, and high densities of Arcuatula senhousia in Lake Shihwa suggest the effects of organic matter accumulation. These results underscore the importance of long-term monitoring and active restoration programs, including ongoing coastal conservation and management.

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