Blue Carbon, carbon that is stored in aquatic ecosystems, has been identified as an essential component of the global carbon cycle with the power to reduce inequities amongst nations through valuation of carbon sequestration in a global Blue Carbon economy. Foundational works discussing Blue Carbon include only three component ecosystems of Blue Carbon, namely mangroves, seagrasses, and salt marshes. Kelp is however capable of very high rates of primary production, with past work recording kelp fixing above 3000 g of carbon per square meter per year. Recent work by Filbee-Dexter and Wernberg (2020) estimated the carbon content of kelp forests in the Australian Great Southern Reef alone to be roughly equivalent to 3% of global Blue Carbon. Kelp forests have additionally been shown to sequester much of the carbon they fix through debris exports to deeper waters.
Comprehensive and accurate Blue Carbon estimates must therefore include kelp forests. Further study is however needed regarding how to include kelp forests into Blue Carbon budgets. Space-based remote sensing, for example multispectral imagery publicly available through the Landsat and Sentinel programs, provides the high quality, periodic data needed to effectively study kelp at a large scale. Considering that past research into Blue Carbon has had an outsized focus on the Global North (e.g., seagrasses, though distributed throughout both hemispheres and all inhabited continents, have been most heavily studied in the Mediterranean and North Atlantic), relying on open data sources that provide planetary coverage, such as those mentioned above, to develop a kelp detection workflow would avoid reinforcing pre-existing geographic biases. If successful, using satellite imagery to map and monitor kelp forests could thus create a global, standardized inventory methodology upon which conservation policies and a
robust Blue Carbon economy could be based.
This proposed doctoral research aims to supply the scientific knowledge required to develop and assess a system using earth observation data to map and monitor kelp forests and their biophysical properties, specifically in Australian waters, to enable their inclusion in Carbon Accounting Systems and a Blue Carbon economy. There are four proposed objectives:
- Evaluate the utility of space-based Earth Observation (EO) in monitoring kelp forests at the regional to national scale, considering ecosystem characteristics that
may affect monitoring success (eg canopy density, water depth, species composition);
- Develop an Earth Observation system for mapping and monitoring kelp forest extent and biomass in Australian waters;
- Quantify the sources and values of uncertainties present throughout kelp extent and biomass mapping processes in the project; and
- Produce a national-scale kelp inventory using publicly available satellite imagery and estimate Australia’s kelp carbon stock and sequestration values with their associated uncertainties.
This work will thus produce not only scientific knowledge and a reproducible methodology, but also a data product that can be used in management and policy decisions, addressing a significant Australian and global knowledge gap.
Professor Stuart Phinn, the University of Queensland
Gillian Rowan, the University of Queensland