Seabed carbon storage overlooked in marine protected area planning

Using marine protected areas (MPAs) to preserve natural carbon storage in key areas of the seafloor could be an additional strategy to help limit climate change, according to a new study led by the University of Victoria. 

To date, interest in natural carbon storage within the ocean, often referred to as “blue carbon,” has typically focused on mangrove forests, salt marshes and seagrass meadows. A new study in FACETS, led by UVic postdoctoral fellow Graham Epstein, argues that seabed sediments may hold greater potential for carbon storage and should also be considered for protection. 

“The soils on the ocean floor may seem empty and unimportant, but they actually contain a unique, diverse and often fragile group of species, and they are vital to marine ecosystems,” says Epstein, who is also a member of Blue Carbon Canada, a UVic-led national research coalition that is evaluating the current and future capacity of natural carbon storage across Canada’s marine habitats. “Seafloor sediments are the final point in the marine carbon cycle, and since they cover the majority of the ocean floor, they make up one of the planet's largest stores of carbon, dwarfing mangroves, seagrass meadows and salt marshes.”

The new study estimates that Canada’s current MPA network encompasses just 11 per cent of the carbon contained in the seafloor down to depths of 2,500 metres, and only around 13 per cent of the carbon hotspots. Working closely with Julia Baum—UVic special advisor in climate and an expert in marine ecology and conservation—Epstein and partners at Oceans North and Fisheries and Oceans Canada found that Canada’s current proposed expansion to MPAs would provide protection to an additional nine per cent of the total seafloor carbon and six per cent of the carbon hotspots.

MPAs were initially created to conserve and recover declining, depleted, rare or fragile species or habitats, but there is growing interest in their ability to provide climate mitigation benefits. Canada’s marine governing body has stated that climate change mitigation is an aim of their MPA network development, but no MPA has yet been designated explicitly considering the protection of carbon storage. Canada has currently designated 15.5 per cent of its seas as MPAs and has joined international commitments to designate 25 per cent by 2025 and 30 per cent by 2030.   

“It is becoming increasingly apparent that industrial marine activities, such as bottom fishing, deep sea mining, marine energy development processes, oil and gas extraction and marine construction can disrupt the carbon found in seabed sediments,” says Susanna Fuller, vice president of conservation and projects at Oceans North. “Protecting important areas of seabed sediment will help to ensure that the carbon stays buried, rather than re-entering the carbon cycle and contributing to climate change.” 

Epstein has also identified and ranked 274 priority areas for future research and potential future spatial protection. These areas were ranked based on the estimated amount of carbon, the potential vulnerability of the carbon, and the ecological and biological significance of the area. In British Columbia, the highest priority areas included the Queen Charlotte Strait and northern Salish Sea, as well as many of the fjords and inlets on the west coast of Vancouver Island and mainland BC. In the Atlantic, highest priority areas include Placentia, Passamaquoddy, Mahone, Trinity bay, as well as parts of the Laurentian Channel and Scotian Shelf.

This research was funded by the Natural Sciences and Engineering Research Council (NSERC), MITACS, Oceans North through an NSERC Alliance grant, Blue Carbon Canada.  

UVic ranked second in Canada and fifth globally for climate action (SDG 13) in 2024. Beyond research initiatives and scholarship focused on climate action, UVic also offers hands-on climate-inspired education including an undergraduate climate science degree, graduate-level coastal climate solutions leaders program and Transformative Climate Action Certificate program. Learn more.

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