Global fleet of underwater robots reveals the phytoplankton hidden beneath the sea surface

What is it about?

Photosynthetic microbes called phytoplankton are responsible for sustaining most of ocean life. Commonly, space satellites are used to monitor these organisms, however, satellites miss out on phytoplankton growing below the sea surface where they are out of the satellite's view. We used data collected by a global fleet of underwater robots to detect these phytoplankton otherwise "hidden" beneath the sea surface. With these robots, we estimate the global biomass of ocean phytoplankton to 343 million metric tonnes, which is roughly equivalent to the weight of 250 million elephants. We find that at least half of the ocean's phytoplankton are too deep for satellites to detect them. We also show how seasonal cycles in phytoplankton biomass are often wrong when satellite observations of chlorophyll-a are used as a stand-in for biomass.

Featured Image

Photo by NOAA on Unsplash

Photo by NOAA on Unsplash

Why is it important?

We show that these underwater robots enable more reliable monitoring of Earth’s phytoplankton, which have implications for the survival of larger organisms like zooplankton, fish, and whales. Having these types of robots to track ocean phytoplankton is urgently needed to understand the impacts of climate change or potential geo-engineering projects implemented in the future.

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