Developing a toolset to evaluate carbon sequestration in New Brunswick mudflats

Mudflats are a globally common intertidal ecosystem, typically located seaward of salt marshes and beaches. They are dubbed a “secret garden” because of their high primary production (capture of CO2), due to the activity of a biofilm of microscopic algae responding to high sunlight and nutrient availability. This productivity, associated with sediment deposition, has potential to result in much long-term carbon storage.

New Brunswick is notable in that its coastlines (Bay of Fundy, southern Gulf of St. Lawrence) are mostly sedimentary. The carbon sequestering potential of the New Brunswick coastlines is thus particularly high; much work is currently occurring to quantify this for salt marshes, but almost nothing has been done for mudflats.

Our team will develop a toolset to evaluate carbon sequestration in large provincial mudflats. The toolset consists of four components: (i) processing 1-m long sediment cores, representing decadal-century scale deposition, to quantify the amount of carbon stored in mudflat sediments, (ii) developing satellite remote sensing methods for mudflats to measure microalgal biofilm biomass, the biotic driver of CO2 uptake in mudflats (ground-truthed with field measurements); (iii) mapping CO2 gas exchange between the mudflat surface and atmosphere using eddy covariance technology, and subsequently modelling the relationship between CO2 fluxes and remotely sensed mudflat microalgal biomass, to be able to estimate CO2 uptake on a large spatial scale;  and (iv) determining underlying drivers with detailed study of gas flux at the mudflat-air interface, photophysiology, identification of microbial species and activity (using environmental DNA and RNA) to best construct the model for CO2 uptake in (iii), and to examine processes subsequently leading to carbon storage in sediments.

Once developed, this toolset will be invaluable to assess the role of one of New Brunswick’s most common coastal ecosystems as a nature-based climate solution, and in providing carbon removal from the atmosphere.