A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO₂

Abstract

Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO2). The carbon (C) sequestered in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds, and salt marshes, has been termed “blue carbon”. Although their global area is one to two orders of magnitude smaller than that of terrestrial forests, the contribution of vegetated coastal habitats per unit area to long‐term C sequestration is much greater, in part because of their efficiency in trapping suspended matter and associated organic C during tidal inundation. Despite the value of mangrove forests, seagrass beds, and salt marshes in sequestering C, and the other goods and services they provide, these systems are being lost at critical rates and action is urgently needed to prevent further degradation and loss. Recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration; however, it is necessary to improve scientific understanding of the underlying mechanisms that control C sequestration in these ecosystems. Here, we identify key areas of uncertainty and specific actions needed to address them.

Using integrated, ecosystem-level management to address intensifying ocean acidification and hypoxia in the California Current large marine ecosystem

“…Considerable interest now centers on the potential for submerged aquatic vegetation (e.g., seagrasses, kelp) to improve local OAH conditions in the near term, and to sequester carbon in the longer term (Mcleod et al, 2011). Although this potential is an area of active investigation, a scientific consensus does not yet exist on the general efficacy of such approaches.…”

Effects of different management regimes on mangrove ecosystem services in Java, Indonesia

“…Mangrove ecosystems sequester carbon within living biomass both aboveground (leaves, stems, roots, branches) and belowground (roots), within non-living biomass (litter and deadwood), and as organic matter within their sediments (Mcleod et al 2011, Alongi 2012. Carbon sequestration in biomass typically takes several decennia at the most, whereas carbon sequestration in sediments is more a matter of millennia (Mcleod et al 2011). Therefore, management impacts that clear vegetation and expose mangrove soils will result in immediate emission of carbon that has been sequestered over generations and more.…”

“…Donato et al 2011), due to the large amount of carbon that accumulates in mangrove soils via other ways than through mangrove growth, i.e. via external sources (Mcleod et al 2011). Soil accumulation in mangrove soils varies widely, and the precise process is further described in Alongi (2012), among others.…”

Eco-certification of Farmed Seafood: Will it Make a Difference?

“…Thus, even if extensive production systems are less demanding when it comes to external input such as feed and fertilizers, the land area appropriated for a given production volume is considerably larger than in intensive aquaculture operations (Lewis et al 2003). Conversion of ecologically valuable ecosystems such as mangroves influences the supply of a range of ecosystem services, and the economic value of unconverted land can be higher than areas modified to aquaculture (Millennium Ecosystem Assessment 2005; Mcleod et al 2011). If smallscale aquaculture farmers are not targeted by eco-certification, the environmental impacts from such systems will not be reduced.…”