Diatom buoyancy reveals secrets of ocean's biological carbon pump
Aquatic microorganisms help oxygenate the Earth's atmosphere. They also transfer photosynthetically fixed carbon from the ocean surface to ocean depths through a sinking mechanism. This mechanism, known as the biological carbon pump, is responsible for most of the ocean's uptake of CO2 arising from human activities. The DIASIN (Integrative eco-mechanics of diatom sinking: Cellular physiology, complex advection and the biological carbon pump) project investigated how the process works. It employed state-of-the-art techniques to understand how diatoms, a common form of phytoplankton, control their buoyancy in response to environmental signals. Researchers combined fluid mechanics, video microscopy, flow cytometry microfluidics, mathematical analysis and computational tools with biochemistry and cell biology techniques. Moreover, a bottom-up approach was used to investigate phenomena at the level of the single organism, before scaling it up to the population and community levels. By integrating both living and physical analyses, scientists were able to better understand the role of buoyancy control in diatoms. Results showed that active buoyancy control significantly improved the probability of cells remaining suspended high up in the water column. This had important implications for phytoplankton ecology and the size structure of the phytoplankton community. DIASIN advanced scientific understanding of the ocean's biological pump and its response to global changes in the environment. This was achieved by understanding the role of the transport of phytoplankton in the environment and its consequences for biogeochemical cycles in the ocean.
Keywords
Diatom, ocean, biological carbon pump, phytoplankton, DIASIN, buoyancy control
