Modeling and Mapping Blue Carbon Storage in Delaware Coastal Marshes

2022 Mid-Atlantic Ocean Forum On-Demand Presentation by Delaware Geological Survey Associate Scientist Daniel Warner.

ABSTRACT: Understanding the spatial patterns of organic carbon storage in coastal marsh ecosystems is key to assessing potential climate change feedbacks as these ecosystems experience shifting hydrologic regimes. Using a set of sediment core data from Blackbird and St. Jones marshes in Delaware, a team at the Delaware Geological Survey evaluated different statistical models for “upscaling” point observations of organic carbon content across the entire marsh platform. Models were compared based on their predictive performance and relative dependence on different input variables. We found that a simple multiple linear regression performed similarly to more complex machine learning approaches and was easy to interpret. We also found that all methods provided a greater predictive performance than a simple mean. We estimated that Blackbird and St. Jones marshes store roughly 70 and 79 gigagrams of organic carbon in the upper 30 cm of their marsh platform, with near-channel areas having the highest levels of carbon storage. We recommend future research focuses on deeper carbon storage in these coastal ecosystems and that care is taken to preserve these near-channel areas from erosion.