you're reading...


Deep Breathing Underwater

Atamanchuk, D., Koelling, J., Send, U., Wallace, D. Rapid transfer of oxygen to the deep ocean mediated by bubbles. Nat. Geosci. (2020). https://doi.org/10.1038/s41561-020-0532-2


The Labrador Sea is one of the lungs of the ocean, breathing in oxygen that supports underwater life across the planet.  A new study finds that climate models drastically underestimate how much oxygen it absorbs—and reveals that the deep ocean is even more vulnerable to climate change than thought.

Birds-eye view of the Labrador Sea. Source: Lauren Dauphin, NASA Earth Observatory


Ocean Lungs and Arteries

With every breath you take, you can thank the ocean.  Marine plants such as phytoplankton, algal plankton, and kelp produce up to 70% of the oxygen in the atmosphere.  They also absorb vast quantities of carbon dioxide, slowing the buildup of this greenhouse gas in the atmosphere and—at least temporarily—reducing the impacts of climate change.

One of the ocean’s lungs is the Labrador Sea.  This sea, which comprises the left arm of the North Atlantic Ocean, is one of the few places where the deep ocean exchanges gases directly with the atmosphere.  Here, oxygen-rich water at the surface becomes so dense that it can sink up to two kilometers, where powerful currents transport it around the globe.  This system of arteries allows oxygen breathed in by the Labrador Sea to support sea life up to thousands of kilometers away.


The Case of the Missing Oxygen

The ocean exchanges oxygen and carbon dioxide with the atmosphere. Source: VITALS

Dissolved oxygen concentrations in the ocean are controlled by biological processes and the exchange of gases between the sea’s surface and the air above it.  Over the past fifty years, the ocean’s inventory of oxygen has decreased by 2%.  Only about 15% of this deoxygenation can be attributed to ocean warming, which decreases the amount of gas it can hold—the same reason why your warm soda tastes flat.  This begs the question of where on earth (or rather, in the ocean) the remaining oxygen is disappearing to.

To tackle such a tricky question, scientists turn to climate models.  Such models allow us to pare down the complexity of nature and simulate important processes.  Scientists construct models based on the laws and equations of physics, chemistry, and biology (i.e., lots and lots of math).  For processes we don’t yet understand well, scientists rely on “parameterizations”, which are approximations of each process.  Parameterizations are one of the main sources of uncertainty in climate models.

However, our climate models are unable to account for the missing oxygen.  In some regions—particularly high-latitude seas such as the Labrador Sea—model predictions of how much oxygen the ocean absorbs are much lower than observed.  Theories abounded for why this might be the case.  In this study, the scientists suspected that the parameterization of gas exchange was missing a key component.

Deployment of the SeaCycler in May 2016 in the central Labrador Sea. Source: Kat Fupsova


Enter the SeaCycler

To test their hunch, researchers from Dalhousie University (Nova Scotia) and the Scripps Institution of Oceanography (California) teamed up to develop a novel sensor system called the SeaCycler.  Costing $1 million, it is the only platform of its kind in the world.  In May 2016, the scientists deployed the SeaCycler at the bottom of the Labrador Sea, 150 meters underwater.  The platform contained an instrument float, which measured key parameters such as oxygen and carbon dioxide as it ascended to the surface every twenty hours.  Meanwhile, a separate communication float transmitted data to a satellite.  Over the course of its yearlong deployment, the SeaCycler made millions of measurements as it quietly listened to the sea breathe.

The SeaCycler’s results were astonishing.  Its data revealed that the Labrador Sea is absorbing 10 times more oxygen than estimated by previous climate models.  Furthermore, two-thirds of this oxygen is absorbed during just 40 days in winter.  The scientists explained this phenomenon as a seasonal “trap door”, which opens during winter when intense storms inject air bubbles into the sea—sort of like a large-scale SodaStream.  Previous gas exchange parameterizations hadn’t included this bubble-injection mechanism, explaining their large underestimations.


Asthma Attack

These findings highlight the vulnerability of ocean ecosystems to climate change.  As human-induced ocean warming causes our ice sheets to melt, more and more fresh water is being added to the Labrador Sea.  Because this water is less dense than seawater, the surface water won’t sink as much as it normally does—and as lead author Dariia Atamanchuk states, the ocean’s “breathing becomes shallower”.  This spells trouble for fish and other creatures that require oxygen to survive in the deep sea, and could also impact ocean nutrient cycles and marine habitats.  In turn, we would feel the impacts on our fisheries and coastal economies.

While alarming, we don’t have to worry that the ocean’s lungs will fail tomorrow—it takes hundreds of years for water formed in the Labrador Sea meander throughout the ocean basins.  Still, as Atamanchuck states, “It is important that we get all these processes right and to predict what will happen in the future with the deep-sea ecosystems.”

Climate change threatens ocean ecosystems. Source: Carbon Brief


Breathe In, Breathe Out

There are two morals to the SeaCycler story.  First, obtaining long-term measurements is imperative to understanding the complex ocean—scientists were only able to capture the trap-door effect through vigilant monitoring of the Labrador Sea over a year.  Second, we need innovative ocean sensors to act as our eyes and ears in the ocean, particularly in harsh regions like the northern seas.  No ship-based mission could have come close to the amount of data collected by the SeaCycler.

Based on the success of the first mission, the team is already hard at work refurbishing the SeaCycler and building a second platform.  Armed with even more sensors, these platforms will be redeployed in the Labrador Sea this September.  The scientists’ ultimate goal is to establish a permanent underwater observatory there so we can monitor the ocean’s health, one breath at a time.  ■



No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 8 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 9 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com