you're reading...


It’s a cold, cold winter for Arctic phytoplankton

Ever wonder what winter is like for marine organisms? What about those that rely on light for growth? In a recent study of microscopic photosynthesizers in some of the most extreme winter conditions in the Arctic, a group of scientists set out to investigate.

Randelhoff, A., Lacour, L., Marec, C., Leymarie, E., Lagunas, J., Xing, X., Darnis, G., Penkerc’h, C., Sampei, M., Fortier, L. and D’ortenzio, F., 2020. Arctic mid-winter phytoplankton growth revealed by autonomous profilers. Science Advances, 6(39), p.eabc2678.

DOI: https://doi.org/10.1126/sciadv.abc2678

Phytoplankton growing beneath sea ice (green patches beneath lighter ice). Image Credit: Andrew Thurber, taken Nov 12, 2012. CC-BY 4.0 license.

Ice, Ice, Baby

Phytoplankton are small microscopic cells that photosynthesize using light to produce energy. Sure, you may have heard of phytoplankton before, but did you know these small cells can even exist in areas with very low light? What about underneath a layer of sea ice that can reach up to 9 feet thick? The phytoplankton of the Arctic can do this, and much more.

Like us, phytoplankton need nutrients to grow. There are more nutrients in some areas of the ocean than others, including areas where waters from depth are moved to the surface or where nutrients run off into the water from ice or land. In the Arctic, nutrients are added to the water from melting ice. Because melting ice requires warmer temperatures and sunlight, much of these nutrients are added during the spring and early summer.

As nutrient additions to the water change with season, small microscopic photosynthesizers bloom in the spring and early summer. Although a majority of phytoplankton growth is expected to occur seasonally, there is very little evidence to support this pattern. Some of this lack of evidence can be attributed to difficult sampling, as waters under the sea ice are also harder to access during the colder winter months. Because of this concept of phytoplankton seasonality and lack of access to waters beneath sea ice, phytoplankton growth during winter months is rarely measured.

How to sample the Arctic

Researchers in a recent study set out to measure phytoplankton growth under the sea ice during the Arctic winter using an autonomous sampler. The sampler is known as an ARGO float and can sample based on remote instructions received from scientists. That means the float can operate autonomously and can send and receive information after surfacing. For this study, researchers programmed the float to avoid sea ice and sample water along different depths.

Image of the Argo float being deployed is shown on the right. Image Credit: Lieutenant Elizabeth Crapo, NOAA.

The float used during this study had sensors for environmental variables (temperature, salinity, etc.) and additional sensors to measure light levels and phytoplankton growth. Light levels were measured using Photosynthetically Active Radiation (PAR), or the range of wavelengths that photosynthetic organisms can use during photosynthesis. Phytoplankton growth can be measured in several ways; in this study scientists used chlorophyll a concentration (the main pigment used to absorb light in photosynthesis that all phytoplankton have) and backscatter (gives an idea of particles in the water column based off the way light reflects off of them). The Argo float combines all of these measurements with sensors that detect light reflection and absorption of different wavelengths to determine how much light was available for photosynthesis and how much phytoplankton growth occurred during winter in the Arctic.

What’s the deal with phytoplankton beneath the ice?

Researchers found phytoplankton growth as early as February under 100 % sea ice cover. These results are especially surprising because light levels were lower than the limit of detection on the sensor and below that expected for photosynthesis. However, the authors did show detectable cell growth and suggested systems and complexes used for photosynthesis need very little light for maintenance during winter.

Image of Baffin Bay where the study took place, between Canada and Greenland. Image Credit: Wikipedia, CC-BY 2.5 license.

Finally, some phytoplankton are mixotrophs and are able to produce energy from both photosynthesis (phototrophy) and by eating other organisms (heterotrophy). The capability of phytoplankton to do both is equivalent to a plant eating a small animal if they don’t get enough sunlight! Authors hypothesize heterotrophy by phytoplankton could be responsible for their survival during winter.

This study is some of the first evidence of consistent phytoplankton growth throughout winter months in the Arctic. Survival and growth of these phytoplankton play a big role in the total amount of cells accumulated during their summertime peak. Because phytoplankton survive at low levels during the winter, they might be able to quickly respond to favorable light conditions and create these characteristic large summer blooms. Phytoplankton in the Arctic play a critical role at the base of a short food web, providing food for larger copepods and eventually larger fish and mammals. As oceans warm and sea ice melts, this trend could change and impact seasonal phytoplankton growth at the base of the Arctic food web.


No comments yet.

Post a Comment


  • by oceanbites 3 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 4 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 5 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 6 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 6 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 7 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 7 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 8 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 8 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 8 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 8 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 9 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 9 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 9 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 10 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 11 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 11 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 12 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 12 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 1 year 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