Quantifying Blue Carbon

RESEARCH PROPOSAL: Quantifying Blue Carbon: Kelp Contribution to Carbon Sequestration in Marine Sediments

Project Summary

Even with Paris carbon emission-reduction commitments the world is facing a mean 3.5°C temperature rise. The promotion of kelp-derived blue carbon sequestration is emerging as an exciting opportunity to mitigate climate change.  Kelp beds are the dominant primary producers in the coastal zone, with global production of 28.3 tonnes CO2eq ha-1yr–1. High-level estimates suggest approximately 11% of carbon fixed by kelp is sequestered near-permanently (100s-1000s of years) in deep (>1,000m) marine sediments. We propose to test this hypothesis with direct data measurement in the New Zealand context, where rich kelp beds and adjacent deep submarine canyons provide a unique ability to produce kelp biomass that can be exported to the deep sea.

This research will support New Zealand’s transition into a low-emission economy by providing data required to include kelp-sequestered carbon into the country’s carbon budget and potentially inclusion in carbon markets. This will incentivise the protection of natural kelp beds and the development of kelp aquaculture, not only for its nutritional, pharmaceutical, mussel co-culture, agricultural, energy and bioremediation opportunities, but also for biological carbon capture and storage. We will quantify the accumulation of kelp-derived carbon in deep-sea environments (continental shelf, slope, and submarine canyons) in the vicinity of natural kelp beds. This will be achieved using a range techniques; stable isotope biomarkers as well as environmental DNA (eDNA) and the highly sensitive droplet digital PCR (ddPCR) method, combined with radiocarbon dating and data on sediment flows and accumulation rates. By determining carbon concentrations, age and biological source along the length of these cores, we will establish for the first time, a relationship between coastal kelp-biomass and the quantity and longevity of kelp-derived carbon sequestration in offshore benthic sediments.

(Bayley, Marengo, Baker, & Pelembe, 2017)