Assessing Carbon Stock and Sequestration of the Tropical Seagrass Meadows in Indonesia

Seagrass meadows provide critical ecosystem services for coastal areas, e.g., as nursery habitats for various fish species, help with water filtration of suspended sediment, and provide food for dugongs ( Dugong dugon ). Their role as “blue carbon” and their capacity to mitigate climate change, by means of Natural mechanism of Carbon Dioxide Removal (NCDR) from the atmosphere, has recently gained increased attention. However, available scientific methods such as guidelines and manuals to measure carbon stock and sequestration still rely heavily on field sampling activities and laboratory analyses. Despite their accuracy, neither of these methods are applicable for large-scale carbon inventories nor are they practical in areas with limited carbon-related data and laboratory resources. Thus, it is necessary to determine whether any of the seagrass-related variables (e.g., coverage, density and biomass) may be treated as a proxy that are both robust and practical to assess the capacity of seagrass to store and sequester carbon. We developed formulas, assessed their robustness, and used both the formulas and the proxy to estimate carbon stock and the sequestration potential of the seagrasses. Furthermore, this study aims to elucidate the carbon stock and sequestration potential capacity of the seagrass ecosystems in Indonesia. We used the data of seagrass- and carbon-related variables obtained from eleven study sites and developed several candidate formulas using the Robust Linear Mixed Models (rL MMs). We found that the best formulas are comprised of multiple seagrass-related variables that consistently include biomass and coverage. This suggests that a combination of biomass and coverage is the best proxy to estimate carbon stock; however, a single proxy of seagrass coverage is recommended for practical seagrass monitoring purposes by the local government. Estimations of carbon stock and sequestration subsequently follow the formulas in the present study. Here we estimated, using a single proxy of seagrass coverage, that the above- and below-ground carbon stock, and carbon sequestration capacity of seagrass ecosystems in Indonesia reached 80–314 ktC, 196–696 ktC, and 1.6–7.4 MtC/year, respectively.