- Scientists discover currents in the Arctic Chukchi sea that significantly speed up the sinking of CO2-carrying phytoplankton
- Research also shows that phytoplankton blooms can be 10 times denser in the darker waters below thick sea ice than in the open water
- These findings could have implications for both the Arctic carbon cycle and marine ecosystems
Stanford University researchers have found that water currents in an Arctic sea significantly accelerate the sinking of CO2-carrying phytoplankton, potentially influencing how much carbon is stored on the seafloor as this part of the planet warms up.
While conducting research at the Chukchi Sea, scientists found that a convergence of currents pushes phytoplankton from under the surface ice to the seafloor at four times the usual speed.
In two newly published papers led by researchers in the lab of Stanford biological oceanographer Kevin Arrigo, the research team presents these findings and explains that blooms of phytoplankton, which need sun to grow, can be 10 times denser in the darker waters below thick sea ice than out in the open water.
Phytoplankton are plant-like organisms that absorb atmospheric CO2 through photosynthesis. When these organisms sink to the ocean floor, some of that captured carbon can ultimately become stored in marine sediments.
The findings from this research could have implications for both the Arctic carbon cycle and marine ecosystems, as phytoplankton also forms part of the basis of marine food chains. These insights can help scientists understand how ocean carbon storage and marine food webs may shift with climate change.
Observations on phytoplankton sinking
In the published papers, the researchers explain that typically, phytoplankton in this region was found to sink with a speed of roughly half a meter per day after blooms peaked.
Through field work done in the Arctic Chukchi sea, the team noticed that locations in which cold water flowing from beneath the ice met warmer opposing currents, the phytoplankton sank downward to the seafloor at four times the usual speed.
This faster sinking may deliver more organic material to organisms living at the bottom of the sea while potentially reducing the food available to species feeding near the surface.
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While this accelerated phytoplankton sinking may contribute to increased CO2 uptake and storage in Arctic sediments, this is yet to be confirmed with research, as factors such as melting ice could create layers of warmer freshwater that prevent nutrient-rich deeper waters from reaching phytoplankton.
Nonetheless, the research provides valuable findings on relatively small-scale ocean currents and the impact they can have on CO2 transport – an aspect that should be considered when estimating the ocean’s role in the global carbon cycle.
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