MONTREAL Beneath the seals and belugas gracefully gliding through Quebec's Saguenay fjord lies a hidden realm of small creatures burrowing into the sea floor mud, which scientists believe play a pivotal role in combating climate change. Earlier this month, researchers from the United Kingdom and Université Laval dedicated several days to the turbid waters of the fjord, sampling from depths of 200 meters as they sought to uncover the life thriving in the sediment.
Dr. Adam Porter, a post-doctoral research fellow at the University of Exeter, described the sea's surface as often appearing an "impenetrable blue." He noted that the sea floor, too, can seem barren at first glance. "When you look at the sea floor, it can often look like there’s not much going on," he stated during a video interview. "But there’s this whole world of life under the mud, and that is playing a really important role in keeping the planet healthy."
This research is part of the Convex Seascape Survey, a collaborative effort aimed at understanding how the sea floor regulates climate by sequestering carbon and the essential functions that small mud-dwelling creatures serve in maintaining ecological balance. Porter humorously referred to the study with its unofficial title: "Trying to make mud sexy."
Rebecca Howman, a PhD student at Université Laval, explained the complexities of gathering approximately 60 sea floor samples, which were challenged by the fluctuating tides, waves, and currents of the Saguenay fjord. "You have to literally take a chunk of the floor off the ground," she noted, highlighting the challenges posed by the fjord's considerable depth. The scientists utilized a "big claw" from their research vessel to scoop samples, which were subsequently transferred to aquariums for study and experimentation.
Despite the messy and muddy process, Howman found the challenges rewarding and enjoyable. Once the samples were extracted from the fjord, they were transported to laboratories in Chicoutimi, Quebec, for further analysis. To monitor the movements of tiny organisms, some barely visible to the naked eye, the researchers sprinkled fluorescent sand atop the mud.
The findings revealed a thriving micro-ecosystem within the sediment, filled with various species such as worms, brittle stars, and bivalves like mussels. Howman noted that while mud may appear lifeless, it is actually home to an astonishing array of life. These small creatures, likened by her to "little ocean gardeners," are integral to maintaining the health of the sea floor and, by extension, the entire marine ecosystem. "The way that they move the sediment changes the entire structure of the ecosystem," she explained, emphasizing their role in modifying nutrient fluxes and oxygenating the sediment.
Additionally, these organisms contribute to carbon storage in the sea floor by consuming or trapping organic matter that falls into their environment, a function that could be vital in addressing the impacts of climate change. Porter highlighted the ocean's floor as "one of the largest carbon stores on Earth," surpassing even the carbon storage capabilities of rainforests.
The concern, according to Porter, is that disturbances to the sea floor from activities like trawling, dredging, or mining could potentially release carbon, undermining global efforts to reduce terrestrial carbon emissions. He expressed hope that the five-year Convex Seascape Survey, conducted in various countries worldwide, will enable researchers to pinpoint important carbon sequestration areas on the sea floor, ultimately influencing policymaking to safeguard these regions. Many nations, including Canada, have committed to protecting 30 percent of the world's land and oceans by 2030, which encompasses the sea floor.
This initiative underscores the significance of preserving marine ecosystems and recognizing their contributions to climate resilience.
