- Seagrass meadows, of which eelgrass is a key species, are some of the most biodiverse and productive ecosystems in the ocean, and play a crucial role in sequestering carbon.
- But eelgrass is disappearing rapidly around the globe, and in Canada, questions remain about where exactly these meadows are distributed, and how effective they are at storing carbon.
- A collaborative project between marine biologists and Indigenous Mi’kmaq communities is attempting to answer these questions in eastern Canada while also restoring lost eelgrass meadows.
- The project could help with eelgrass’s long-term survival in the area, as researchers identify eelgrass populations that are more resilient to climate change, and communities work toward eelgrass conservation.
MALIKO’MIJK, Canada — Decades ago, the sea around Maliko’mijk Island was an expansive green carpet of eelgrass, the meadows so thick that members of the Pictou Landing First Nation had to cut channels through them for their boats to pass.
But on a drizzly September day, as boats carrying scientists and elders pull up to the island, which hugs the north shore of Canada’s Nova Scotia province, the seafloor beneath is brown and bare.
“It’s a very special place for my people,” says Pictou Landing Chief Ann Francis-Muise, standing on the shore. “When we were growing up, our family members would take us out spearing eels. There seems to be a huge change over the years.”
This decline isn’t only a problem for this community. Across North America, meadows of marine eelgrass (Zostera marina) are in decline due to pollution, seabed disturbance, invasive species and warming water. This has implications for biodiversity, coastal erosion and climate change, since eelgrass plays an outsize role in pulling carbon dioxide out of the atmosphere.
Even as the loss of eelgrass becomes increasingly apparent, many knowledge gaps remain, from where it’s distributed, to just how effective it is at sequestering carbon. Either way, for Indigenous communities, the consequences of eelgrass loss are clear, and on the east coast of Canada, a project that partners researchers with Mi’kmaq knowledge holders and land users is now attempting to reverse that decline — with potential benefits for communities, and for the planet.
Filling the gaps with traditional knowledge
Across the planet, seagrass meadows, of which eelgrass is a key species, are some of the most biodiverse and productive ecosystems in the ocean. In Canada, eelgrass is found on all three coasts, where it supports species ranging from salmon to geese to eels. Research indicates eelgrass may also punch far above its weight in stabilizing the climate, with some studies suggesting that, acre for acre, seagrasses sequester two times more carbon than forests, mostly by locking it into the sediments beneath them.
But both globally and in Canada, seagrasses are threatened; studies estimate that almost a third of seagrass meadows have disappeared around the world in recent decades. In Canada, some studies estimate that 31% of eelgrass beds are declining on the country’s Atlantic coast, while in places like James Bay, in northern Canada, that figure is 75%.
Yet these estimates are complicated by the fact that no comprehensive mapping of eelgrass distribution exists for the country, posing a challenge for restoration.
“We have no idea where we had eelgrass or where we’ve lost eelgrass,” says Dalhousie University research scientist Kristina Boerder, lead scientist for the Community Eelgrass Restoration Project, which she says is a first-in-Canada approach, combining community-led eelgrass restoration with a climate change focus. “So, a lot of what we’re working on is talking to people to understand what has happened in the past.”
The Community Eelgrass Restoration Project aims to fill in the gaps in the inventory of past and present eelgrass distribution around Nova Scotia, and use that inventory to guide restoration.
On the north shore of Nova Scotia, that’s meant partnering with Indigenous communities to identify where eelgrass is still growing, and where it might be coaxed into growing again. That’s why, in early September, Boerder and other researchers hauled a box containing 1,000 shoots of eelgrass, harvested from a healthy bed they’d identified with help from members of the Pictou Landing First Nation, onto the beach at Maliko’mijk.
The island is a particularly sacred site, says Trinity Nicholas from the Pictou Landing First Nation’s Indigenous Habitat Participation program, as the area has been occupied by the Mi’kmaq for thousands of years.
“Maliko’mijk is our community’s original birthplace,” Nicholas says. “Originally, we would fish and hunt around there.”
While the eelgrass meadows shelter a range of species from clams to lobsters, one of the traditional food sources that was particularly important was American eel (Anguilla rostrata) or kataq in Mi’kmaq. “[Eels] are the Mi’kmaq’s number one food source. They exist almost all year around, you can fish them, it’s like our life, pretty much,” Nicholas says. “But there are no eels anymore, because our eelgrass is depleting.”
Prompted by concerns raised by community members about eels, the Pictou Landing First Nation and the Confederacy of Mainland Mi’kmaq (which represents eight Mi’kmaq communities in Nova Scotia) have partnered with Dalhousie University researchers on the eelgrass restoration project. The goal of the project is to bring some of that habitat back, by transplanting eelgrass harvested from other sites to places like Maliko’mijk.
It’s not the only concern. Pictou Landing is also facing significant erosion, including from a devastating hurricane in 2022, where up to 3 meters (10 feet) of shoreline disappeared overnight. The community is also dealing with the consequences of serving as the dumping ground for a nearby pulp mill for decades.
Because eelgrass helps protect against erosion and storm surge by stabilizing sediment and slowing wave energy, Nicholas says bringing back eelgrass could help with the remediation of the former effluent treatment site in the nearby estuary known as A’se’k, or Boat Harbour, which will require more shoreline protection, particularly as climate change has greater impacts on the area.
Can it take the heat?
But that’s not the only climate focus of the restoration project. Researchers are beginning to study populations of eelgrass that may be more likely to withstand changing ocean conditions — and quantifying how much of a role eelgrass itself is playing in mitigating climate change.
In the lab, some of this work involves exposing eelgrass seeds gathered in the wild to different levels of temperature and salinity.
“They represent the conditions that we’ll find it in, 10, 20, 50 years down the road,” says Derek Tittensor, project head and head of the Future of Marine Ecosystems research lab at Dalhousie. “We’ll see how well do those seeds germinate, how well does the eelgrass grow in these warmer conditions. And from that, what we can expect in terms of the future of eelgrass.”
This is being combined with work looking at the genetic differences among eelgrasses around the province, to determine which populations of eelgrass are more likely to withstand projected conditions. This would then be used to guide decisions about which populations to restore in the future.
“That’s part of the resilience,” Tittensor says. “Can we learn in the lab and use that to inform what we do in the field?”
Crafting a better understanding of eelgrass’s climate change resilience isn’t only important for places like Maliko’mijk. Because eelgrass stores carbon in the sediment, researchers are also taking sediment cores from eelgrass meadows to understand how long the carbon in those sediments is stored. They’re applying radiocarbon dating and other tools to samples to determine the age of the carbon they contain.
Markus Kienast, oceanography professor at Dalhousie who’s contributing his expertise on sediment geochemistry to the project, says this helps determine whether the carbon that eelgrass takes out of the atmosphere only stays stored as long as the plant is alive — or if it remains locked away for millennia.
“Because then if you disturb an eelgrass bed, you’re not only disturbing the carbon that is being stored now, but also carbon that has been stored there for any amount of time, which would make disturbance all the more harmful,” he says.
Kienast says this temporal dimension is a gap in the data not only for eelgrass and other forms of blue carbon (carbon stored in marine ecosystems), but also for many carbon stock assessments. And yet it’s a critical part of any climate mitigation discussion.
“Only if we understand the time scale of storage involved will we be able to make meaningful predictions,” he says. “The key question is, how long?”
Seeding a new future
Despite the gaps, Boerder says the blue carbon dimension of the project is already the source of intense interest from government officials and industry players, in part because of the potential for the carbon credit market. Boerder says the project is also in discussion with the U.S. Environmental Protection Agency, which is interested in the potential to extend its blue carbon research and eelgrass inventory into higher latitudes, as those efforts currently stop at the border.
But for community members, the relationship between eelgrass and climate change can be an abstract one — until people can see the connection mapped out in front of them.
“When I can point to [how] this stores carbon right there, and we’re measuring it right in there, that’s something people can relate to,” Boerder says.
Collaborating with communities, especially Indigenous communities who are already focused on conservation while also greatly affected by environmental changes, not only increases awareness of the carbon sequestration potential of eelgrass, but also supports the kind of care for and pride in the ecosystem that is crucial for eelgrass’s long-term survival, Boerder says.
This is particularly true for the Pictou Landing First Nation, where eelgrass restoration represents a chance for community members to repair a relationship damaged by colonization and industrial activity.
“Our community needs to know what’s going on within conservation so we can start it in our own community,” Nicholas says. “It’s like, we can’t become victims to environmental racism again, where we have the knowledge to stop it before it even starts — and even though it’s not our fault, we’re still restoring it.”
At Maliko’mijk, elders, families and scientists wade into the water with shoots of eelgrass in their hands, stooping to plant each blade beneath the muddy water. Watching from shore, Chief Francis-Muise reflects that it’s important to support the practices that carry on traditions, and that replanting is just the beginning. The community will have to keep an eye on the transplants through the winter, she says — and come back with more plants next year.
“This is all a learning process for us also, but we’re willing to help, we’re willing to share,” she says. “We’re just trying to keep everything alive.”
Banner image: Participants in an eelgrass coring workshop gather sediment cores from an eelgrass meadow, which will be used to establish how long the carbon stored by eelgrass stays locked away. Image courtesy of Nicolas Winkler/The Community Eelgrass Restoration project.
Underwater gardeners restore seagrass meadows to keep oceans healthy
Also by this reporter:
In Canada, Indigenous communities and scientists collaborate on marine research
Related audio from Mongabay’s podcast: A discussion of Indigenous stewardship of seagrass meadows in Mexico and a conversation with a Canadian marine biologist who partners with Mi’kmaq communities to blend western science and Indigenous knowledge (‘two-eyed seeing’), listen here:
Citations:
Mcleod, E., Chmura, G. L., Bouillon, S., Salm, R., Björk, M., Duarte, C. M., … Silliman, B. R. (2011). A blueprint for blue carbon: Toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment, 9(10), 552-560. doi:10.1890/110004
Waycott, M., Duarte, C. M., Carruthers, T. J., Orth, R. J., Dennison, W. C., Olyarnik, S., … Williams, S. L. (2009). Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proceedings of the National Academy of Sciences, 106(30), 12377-12381. doi:10.1073/pnas.0905620106
Murphy, G. E., Dunic, J. C., Adamczyk, E. M., Bittick, S. J., Côté, I. M., Cristiani, J., … Wong, M. C. (2021). From coast to coast to coast: Ecology and management of seagrass ecosystems across Canada. FACETS, 6(1), 139-179. doi:10.1139/facets-2020-0020
Krause-Jensen, D., Archambault, P., Assis, J., Bartsch, I., Bischof, K., Filbee-Dexter, K., … Duarte, C. M. (2020). Imprint of climate change on Pan-Arctic marine vegetation. Frontiers in Marine Science, 7. doi:10.3389/fmars.2020.617324
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Correction: Kristina Boerder is the lead scientist, not project lead. Derek Tittensor is the project head and head of the Future of Marine Ecosystems research lab at Dalhousie. We regret the error.
