An unintended ecological benefit from human intervention: The enhancement of carbon storage in seagrass meadows

Human interventions have had unintended consequences for the diverse functions of various ecosystems. Hydrological interventions have the potential to alter vegetated habitats in coastal nearshore ecosystems, but little is known about the impacts on organic carbon (C-org) sequestration, which plays an important role in climate change mitigation. We examined the effects of past human interventions through artificial inlet opening in a lagoonal seagrass meadow. The sediment profiles of geological and biogeochemical characteristics were measured to obtain the historical changes in the lagoon environment and C-org accumulation rates. Isotopic and elemental signatures and diatom assemblages showed that the interventions increased the duration of seawater exchanges and the extent of the seagrass meadow. C-org accumulation rates increased more than 1.9-fold after the intervention, resulting in additional C-org storage in the seagrass meadow during last 64 years. Synthesis and applications. Artificial opening of tidal inlet can potentially provide unintended ecological benefits, such as increased carbon sequestration in seagrass meadows. Hydrological interventions could be undertaken intentionally as a potential active intervention to sequester carbon, as well as control flood risk and provide other benefits to people in estuarine systems. Our results illustrate that physical factors such as improving salinity conditions and mineral particle supply have an impact on the feasibility of hydrological interventions for enhancing carbon sequestration. We propose that biogeochemical-physical coupled approach will help stakeholders to evaluate the ecological and social risks and synergies of implementing hydrological interventions.

Automated summary

Human interventions in ecosystems, such as artificial inlet opening in seagrass meadows, have shown to have unintended consequences on carbon sequestration. This study found that interventions led to a significant increase in C-org accumulation rates, resulting in additional carbon storage in the meadow over the past 64 years. The findings suggest that hydrological interventions could potentially be used for active carbon sequestration and to provide ecological and social benefits in estuarine systems.