Carbon sequestration in Ecuadorian mangroves (2012)

Undergraduates: Amanda DelVecchia, Ovik Banerjee, Juan de Dios Morales

Faculty Advisor: John Bruno
Department: Environmental Science

---

Mangroves are thought to be highly efficient carbon sinks due to their ability to accrete organic matter. However, few estimates of long-term storage potential exist, limiting the assessment of these ecosystems in global carbon accounting. We measured depth profiles of soil organic carbon content in 72 cores collected from six sites (three natural and three restored) surrounding Muisne, Ecuador. Samples up to 1m deep were analyzed for organic matter content using loss-on-ignition; values were converted to organic carbon content using an accepted ratio of 1.72 (g/g). Results suggest that average soil carbon density is 0.046 ± 0.009 g?cm^(-3) (3.7 ± 2.0% carbon content by dry mass) at approximately 1m deep in natural sites, and 0.038 ± 0.011 g?cm^(-3) (5.3 ± 1.5%) in restored sites. These findings are concordant with those previously measured using shorter (0.5m) cores and indicate that organic carbon buried below 0.5m may be refractory, providing evidence of carbon sequestration in mangroves on the Pacific coast of South America. Pb-210 and peak Cs-137 levels are being used to estimate sediment accretion rates and burial fluxes, which will allow us to calculate long-term carbon sequestration rates that are crucial for evaluating mangrove conservation as a climate change mitigation strategy.