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Despite making up a tiny percentage of the world’s total biomass, phytoplankton are responsible for drawing down a huge share of the new CO2 produced by ecosystems and human activities

Phytoplankton, microscopic organisms living in aquatic environments, play an outsized role in global carbon fixation. Despite their small biomass compared to other forms of life on Earth, they are vital in regulating atmospheric CO2 levels.1 Their estimated global biomass is less than two gigatons of carbon (GtC), which is minuscule compared to terrestrial vegetation and marine animals.2 However, their impact on carbon fixation is immense.

Role in Carbon Fixation​

Phytoplankton play a crucial role in the global carbon cycle, fixing approximately 45-50 billion tonnes of inorganic carbon annually through photosynthesis.345 This amount is comparable to the net primary productivity of all terrestrial plants.67 Phytoplankton utilize carbon concentrating mechanisms to maintain efficient growth across a range of CO2 concentrations.8 Their productivity is influenced by various factors, including light availability, nutrient levels, and climate variability.94 Satellite-based models have been developed to estimate global primary production, incorporating parameters such as sea surface chlorophyll concentrations and temperature.9 Phytoplankton also contribute to carbon sequestration through biological and carbonate pump mechanisms, potentially storing carbon in seafloor sediments for thousands of years.10

Diverse and Abundant​

Despite their small size, phytoplankton species are incredibly diverse. Estimates suggest there may be more than 10,000 species, each contributing uniquely to the robustness of marine ecosystems.11 This diversity ensures ecological resilience and adaptability to environmental changes, further emphasizing the essential role these organisms play in ocean health and global climate regulation.1213

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Footnotes​

  1. Falkowski, P. G. (1994). The role of phytoplankton photosynthesis in global biogeochemical cycles. Photosynthesis Research, 39(3), 235-258. https://doi.org/10.1007/BF00014586 ↩

  2. Buitenhuis, E. T., Li, W. K. W., Vaulot, D., Lomas, M. W., Landry, M. R., Partensky, F., Karl, D. M., Ulloa, O., Campbell, L., Jacquet, S., Lantoine, F., Chavez, F. P., Macias, D., Gosselin, M., & McManus, G. B. (2012). Picophytoplankton biomass distribution in the global ocean. Earth System Science Data, 4, 37-46. ↩

  3. Longhurst, A., Sathyendranath, S., Platt, T., & Caverhill, C. (1995). An estimate of global primary production in the ocean from satellite radiometer data. Journal Name, Volume(Issue), Pages. [If available, provide the journal name, volume, issue, and pages.] ↩

  4. Falkowski, P. G., Barber, R. T., & Smetacek, V. (1998). Biogeochemical controls and feedbacks on ocean primary production. Science, 281(5374), 200-206. ↩ ↩2

  5. Chavez, F. P., Messié, M., & Pennington, J. T. (2011). Marine primary production in relation to climate variability and change. Annual Review of Marine Science, 3(1), 227-260. ↩

  6. Falkowski, P. G. (1994). Light utilization and photoinhibition of photosynthesis in marine phytoplankton. In Photoinhibition of Photosynthesis (pp. 407-432). BIOS Scientific Publishers. ↩

  7. Sui, N., Huang, F., & Liu, L.-N. (2020). Photosynthesis in phytoplankton: Insights from the newly discovered biological inorganic carbon pumps. Molecular Plant, 13(7), 949-951. ↩

  8. Tortell, P. D., Rau, G. H., & Morel, F. M. M. (2000). Inorganic carbon acquisition in coastal Pacific phytoplankton communities. Limnology and Oceanography, 45(7), 1485-1500. ↩

  9. Behrenfeld, M. J., & Falkowski, P. G. (1997). Photosynthetic rates derived from satellite-based chlorophyll concentration. Limnology and Oceanography, 42(1), 1-20. ↩ ↩2

  10. Firdaus, M. R., & Wijayanti, L. A. S. (2019). Fitoplankton dan siklus karbon global. Oseana, 44(2), 35-48. ↩

  11. Righetti, D., Vogt, M., Zimmermann, N. E., Guiry, M. D., & Gruber, N. (2020). PhytoBase: A global synthesis of open-ocean phytoplankton occurrences. Earth System Science Data, 12(2), 907-933. ↩

  12. Falkowski, P. G., & Raven, J. A. (2013). Aquatic photosynthesis. Princeton University Press. ↩

  13. Mann, D. G., & Vanormelingen, P. (2013). An inordinate fondness? The number, distributions, and origins of diatom species. Journal of Eukaryotic Microbiology, 60(4), 414-420. ↩