A group of researchers analyzed ocean floor samples (and their DNA) from worldwide. They found that nearly two-thirds of the lifeforms represented by the DNA are undiscovered creatures. According to their recent study, diverse and unknown plankton are sequestering carbon dioxide (CO2) along the ocean floor, mainly in the deep sediment and “hotspots” near Earth’s poles.
These mysterious plankton are part of the biological carbon pump (BCP). This vital planetary system takes carbon from the atmosphere and moves it to the ocean floor, where it is trapped for potentially millions of years. Through this BCP (also called a marine carbon pump), plankton and other critters absorb CO2 at the ocean’s upper levels and eventually carry it in their bodily tissues to the seafloor—typically because they have died and sank.
The new study, published on Feb 4, 2022, in the journal Science Advances, found that in addition to dead, sunken plankton on the seafloor, there is plenty of living, undiscovered organisms. The researchers are from the University of Geneva, CNRS (the French national center for scientific research), Genoscope and IFREMER in France, the Bjerknes Center for Climate Research in Norway, and the Norwegian Research Center.
Colomban de Vargas, a researcher at CNRS, said:
For the first time, we can understand which members of plankton communities are contributing most to the biological pump, arguably the most fundamental ecosystem process in the oceans.
The team developed a database from over 400 deep ocean sediments samples collected from 2010 to 2016. Then, they compared those samples to roughly 1,300 other previously acquired samples. “This provides the first unified vision of the full ocean eukaryotic biodiversity, from the surface to the deep-ocean sediment, allowing marine ecological questions to be addressed for the first time at a global scale and across the three-dimensional space of the ocean, representing a major step towards ‘One Ocean ecology,’” the team explained.
The sediment samples revealed the existence of diverse plankton that help with sequestration. In addition, the team confirmed that polar regions are carbon sequestration hotspots and that the plankton DNA in the seafloor sediments can reveal the strength of the BCP.
Previously, scientists have estimated that our ocean absorbs approximately 40% of the CO2 humans produce. These findings highlight how significant the seafloor ecosystem is to this natural process.
Andrew J. Gooday, researcher and Emeritus Fellow at the National Oceanography Center, Southampton, concluded:
Our study further demonstrates that deep-sea biodiversity research is of paramount importance. Huge numbers of unknown organisms inhabit ocean-floor sediments and must play a fundamental role in ecological and biogeochemical processes.
A better knowledge of this rich diversity is crucial if we are to protect these vast, relatively pristine ecosystems from the impacts of possible future human incursions and understand the effects on it of climate change.
However, our oceans do absorb more than just CO2. In two somewhat related studies, we reported on just how much heat the oceans may be absorbing and how an overabundance of CO2 has caused mass toxic algae growth. An international team of researchers had calculated that the oceans collectively absorb heat at a rate of 5 atom bombs per second. In the Canary Islands, another group found that toxic algae blooms happen when CO2 in the water reaches high levels.
Therefore, while one positive may be that a large mass of CO2 is sunk into our oceans, two negatives may be how quickly they are heating up and the overall marine life which could be lost prior to the CO2 sinking. As tends to be the case with ecosystems, a delicate balance is often required to ensure a harmonious environment.
So, can deep-sea plankton save the planet? Maybe not single-handedly, but they can reduce ocean acidification (which causes toxic algae blooms) and mitigate climate change by drastically reducing atmospheric CO2 levels.
Other fascinating deep-sea creatures include the ultra-black fish that absorbs 99.5% of light and eyeless shrimp that have a light-sensing organ on their backs, which allow them to detect low levels of illumination.
