//
you're reading...

Biogeochemistry

Ocean eddies suck carbon out of the atmosphere, thanks to plankton

Article: Omand, Melissa et al. (2015) “Eddy-driven subduction exports particulate organic carbon from the spring bloom” Science 10.1126

 

Planktonic Pumping

Phytoplankton represent one of the few ways the environment can pull carbon dioxide out of the atmosphere and store it somewhat permanently. These photosynthetic microorganisms, which mostly live near the ocean surface, take in CO2 from the atmosphere in order to grow. Being heavier than water, phytoplankton tend to sink, and if they sink deep enough, that carbon can stay down in the depths of the ocean for tens of thousands of years. This process, termed the ‘biological pump’, keeps the atmospheric CO2 concentration appreciably lower than it otherwise would be [Fig. 1].

oceanbites_cael_october_fig1

Figure 1: Diatoms are a type of large phytoplankton that often dominate blooms in many parts of the ocean. Their size and hard silicate shells cause them to sink quicker than other plankton. Image courtesy UC Berkeley.

The biological pump is generally thought to be driven by this process of plankton sinking from the surface, where there’s enough light for them to grow, into deeper waters where they eventually serve as the energy source for deep ocean communities.   Phytoplankton, however, are only slightly denser than the water they live in, and very small, so they sink very slowly compared to the total depth of the ocean. Many are too small and buoyant to sink at all. Moreover, this picture ignores the fact that the ocean moves!

 

Well, The Ocean Does Move – So What?

Recent work by scientists from Woods Hole Oceanographic Institution, the University of Washington, and the University of Maine, suggests that much of this carbon export to the deep ocean may actually be due to mixing by ocean eddies (oceanic whirlpools). This represents a paradigm shift in our understanding of how carbon is removed from the atmosphere; the turbulence of the ocean may play a major and active climate role by pushing carbon-rich water into the deep.

A crucial time to investigate the role between ocean turbulence and sinking, carbon-rich phytoplankton is during a “bloom.” Large phytoplankton blooms are generally triggered in springtime, similar to the flowering of terrestrial plants. In spring, more light is available, and weaker winds allow the surface layer of the ocean to shallow, bringing nutrients up into well-lit regions and stimulating plankton growth.

The investigators took measurements during one of these blooms in the North Atlantic using both gliders (underwater autonomous vehicles) and ‘Lagrangian floats’ which passively drift with water below the surface [Fig. 2]. The gliders and floats collected all sorts of physical, chemical, and biological data from which the authors could determine details about the carbon content of the water and how it had gotten there. They compared the data they collected with high-resolution computer simulations of ocean stirring along fronts, which included a model of phytoplankton.

oceanbites_cael_october_fig2aoceanbites_cael_october_fig2b

Figure 2: a) a Seaglider, which flies through the water and collects data. Image courtesy the Alfred Wegner Institute. b) a Lagrangian float, which follows the motion of a parcel of seawater. Image courtesy U. Washington.

 

 

How Does This Work?

Just like in weather patterns, ocean fronts occur at the boundaries of different water masses. Where a heavier (either colder or saltier) body of water meets a lighter (warmer or fresher) one, this results in a horizontal gradient, or change, in density. These fronts are often the sites of photosynthetic activity as well as stronger and more turbulent ocean activity. Eddies that spin along such fronts will swap lighter water from one region with heavier water from the other, and in the process will cause filamentary tongues of the heavier or intermediate density water to slide underneath the lighter water [Fig. 3]. This sinking of heavier filaments also pushes deeper, nutrient-rich water upwards, stimulating further plankton growth. Thus, this horizontal mixing process pushes carbon-rich surface waters downwards, in exchange for nutrient-rich, carbon-depleted waters. This process ultimately results in injections of carbon into the deep ocean.

oceanbites_october_cael_fig3

Figure 3: A computer simulation of an eddy along a front. The front starts very smooth – with warm/light water (red) on the right side and cold/heavy water (blue) on the left – then turbulence sets in and eddies form. As a result, some denser surface water (white and light blue) is sucked underneath the warmer surface water. If the surface water being pulled down by the eddy contains carbon-rich plankton communities, this will effectively remove carbon from the atmosphere. Image courtesy Dr. John Taylor, U. Cambridge.

 

 

Significance

This mixing process was found both in the observational data and in the model simulations. By combining multiple approaches, the researchers provide a compelling picture of the importance of ocean eddies for the biological pump. They found that in regions with strong currents & fronts, like the waters off the coast of East Asia, the Eastern US, and around Antarctica, subduction by eddies during spring blooms may be responsible for half of the sinking carbon. Beyond changing our ideas about what contributes to the ocean’s uptake of atmospheric carbon, these results may lead to new estimates of the deep ocean’s ability to uptake carbon. A better understanding where, how, & how fast carbon can go into the ocean’s remote depths can lead to better predictions of the global impacts of anthropogenic carbon emissions.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 1 day 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 1 month 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 1 month 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 2 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 2 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 3 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 3 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 3 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 3 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 4 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 4 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 4 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 5 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 6 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 6 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 7 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 7 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 8 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 
  • by oceanbites 8 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
  • by oceanbites 8 months ago
    Have you seen a remote working setup like this? This is a photo from one of our Oceanbites team members Anne Hartwell. “A view from inside the control can of an underwater robot we used to explore the deep parts
WP2Social Auto Publish Powered By : XYZScripts.com