Microscopic organisms in the ocean are essential for removing carbon dioxide from the atmosphere. A recent study has revealed an overlooked biological factor that could transform our understanding of this process, enhancing the accuracy of climate change forecasts.
New research led by Stanford introduces a previously unknown factor that might alter our comprehension of how oceans help mitigate climate change. Published on October 11 in Science, this study has disclosed the existence of unique mucus “parachutes” created by tiny marine organisms that significantly slow their descent. This slowing is vital for the process of drawing carbon dioxide out of the atmosphere. The findings indicate that earlier calculations of the ocean’s capability to sequester carbon may have been inflated, while also providing insights that could refine climate models and guide policymakers in their climate change mitigation efforts.
“We’ve been looking at this issue from the wrong angle,” stated senior author Manu Prakash, who is an associate professor of bioengineering and ocean studies at Stanford’s School of Engineering and Stanford Doerr School of Sustainability. “Our findings highlight the importance of basic scientific observation and studying natural processes in their authentic environments, which is essential for our climate change mitigation strategies.”
The Biological Pump
Marine snow, which consists of a combination of decaying phytoplankton, microbes, fecal matter, and other organic particles, absorbs nearly a third of all human-generated carbon dioxide from the air, transporting it to the ocean floor where it can remain for thousands of years. Although scientists have been aware of this efficient dispersal mechanism, dubbed the biological pump, the specifics of how these fragile particles descend through the ocean—average depths of 4 kilometers (2.5 miles)—has remained elusive until now.
To unlock this mystery, researchers utilized an innovative device—a rotating microscope developed in Prakash’s lab, which turns the challenge on its head. This apparatus mimics the movements of organisms, simulating vertical travel across limitless distances while adjusting variables like temperature, light, and pressure to mirror specific oceanic conditions.
For five years, Prakash and his team have utilized these specially designed microscopes aboard research vessels across all major oceans, from the Arctic region to Antarctica. During a recent mission in the Gulf of Maine, they gathered marine snow by deploying traps in the water, then swiftly examined the particles’ sinking dynamics using their rotating microscope. As marine snow is an active ecosystem, capturing these measurements at sea was crucial. The rotating microscope provided the research team with the opportunity to study marine snow in its natural habitat with unprecedented detail—something previously unattainable in distant laboratories.
The findings were surprising. They showed that marine snow sometimes forms parachute-like mucus structures that can effectively extend the time these organisms remain suspended in the upper 100 meters of the ocean. This extended stay enhances the likelihood that other microorganisms will decompose the organic carbon within the marine snow, converting it back into organic carbon accessible to other plankton—which effectively pauses the absorption of carbon dioxide from the atmosphere.
Beauty and Complexity in the smallest Details
The study exemplifies the necessity of observation-driven research to grasp how the slightest biological and physical processes function within natural ecosystems.
“Theoretical models suggest how the flow behaves around small particles, but what we witnessed at sea was strikingly different,” remarked lead author Rahul Chajwa, a postdoctoral researcher in Prakash’s lab. “We are just beginning to grasp these intricate dynamics.”
This research highlights an important point: for the past 200 years, scientists have examined life forms, including plankton, primarily in a two-dimensional space, trapped under microscope slides. In contrast, high-resolution microscopy can be incredibly challenging in the open ocean. Chajwa and Prakash stress the critical need to conduct scientific observations as close to their natural conditions as possible.
They argue that funding agencies, both public and private, should prioritize research that emphasizes observational studies in natural settings.
“Without replicating the environment where life evolved, we can’t even ask the fundamental questions about what life actually does,” Prakash asserted. “By removing biology from its natural surroundings, we lose the ability to ask relevant questions.”
Aside from its direct implications for measuring marine carbon sequestration, the study also showcases the inherent beauty of ordinary phenomena. Similar to how sugar dissolves in coffee, the process of marine snow sinking into the ocean’s depths is a complex interaction influenced by often unnoticed factors.
“We often overlook simple phenomena, but straightforward concepts can have significant impacts,” Prakash noted. “When we observe details—like the mucus tails of marine snow—we unlock new possibilities for understanding the fundamental principles of our world.”
The researchers are now working to enhance their models, integrate their findings into Earth-scale models, and share an open dataset from their six global expeditions, which will represent the largest collection of direct marine snow sedimentation observations ever compiled. They also plan to explore the elements that affect mucus production, including environmental stressors and specific bacterial species.
While this discovery challenges previous notions regarding tipping points in ocean-based carbon sequestration, Prakash and his team remain optimistic. During a recent expedition near Northern California, they identified mechanisms that could potentially accelerate carbon sequestration.
“Every time I investigate the plankton world with our tools, I gain a new insight,” Prakash remarked.
