//
you're reading...

Climate Change

The Meltdown: Protists in the time of disappearing Sea Ice in the Arctic Ocean

Original Research Article:

Hardge, K., Peeken, I., Neuhaus, S., Lange, B.A., Stock, A., Stoeck, T., Weinisch, L., and Metfies, K. (2017). The importance of sea ice for exchange of habitat-specific protist communities in the Central Arctic Ocean. Journal of Marine Systems 165, 124–138. Doi: 10.1016/j.jmarsys.2016.10.004

See, Ice!

Werner Herzog once famously noted, “Civilization is like a thin layer of ice upon a deep ocean of chaos and darkness”. As we know, that thin layer of ice he refers to is not simply a figure of speech, but a real part of our ecosystem, found in both the Arctic and Antarctic polar oceans. Named sea ice, it is frozen ocean water, covering over 3-7% of the planet’s surface depending on the season (it melts in the summer and grows during winter months) (Fig 1a). Sea ice is a critical component of our planet because it maintains the cool temperature of the poles, influences ocean circulation and plays a crucial role in the structure of polar ecosystems. Figures collected from the National Snow and Ice Data Center indicate a 13.4% decline in minimum Arctic sea ice since the 1980’s and 90’s (Fig 1b), increasing the likelihood that the polar biosphere could disappear by 2020.

(a) (left) Maximum Arctic sea ice occurs in Feb/March due to freezing (right) Minimum is in September (b) The Arctic sea ice maximum and minimum (shown) levels have been decreasing for nearly 30 years. Image courtesy Earth Observatory, NASA.

(a) (left) Maximum Arctic sea ice occurs in Feb/March due to freezing (right) Minimum is in September (b) The Arctic sea ice maximum and minimum (shown) levels have been decreasing for nearly 30 years. Image courtesy Earth Observatory, NASA.

I, protist

The Arctic marine community consists of a vast range of life forms, but it would not function without the presence of a group of single-celled organisms collectively called protists (not considered plant, fungus or animal), which range from unicellular algae, protozoa (microorganisms with hair or whip-like projections), and phytoplankton (photosynthetic organisms that live suspended in water). Protists that live under sea ice are one of the primary energy sources for all organisms higher up on the food chain in the marine ecosystem, and assist in pulling CO2 from the atmosphere, thereby reducing CO2’s presence as a greenhouse gas. Since protists are specifically adapted to the environmental conditions of the Arctic, decreasing sea ice initiated by climate change poses a serious threat to protist, and all ocean diversity. It is therefore vital to assess current trends and predict future changes in protist communities in Arctic ecosystems.

The quest

Kristin Hardge and her colleagues from the Helmholtz Centre for Polar and Marine Research and other institutes decided to investigate these essential, yet understudied microorganisms in the Central Arctic Ocean during the summer of 2012 (the year with record low minimum sea ice). They aimed to answer the following three questions:

(1) Do different habitats in the ice-covered Arctic Ocean shelter specific kinds of protists?

(2) Do protists that live in all types of habitats have preferences for which types of habitats they call “home”?

(3) Can melting of sea ice cause protists from one habitat to shift to another?

How and where they looked beneath the surface

Collection

The team collected water samples from seven ice stations in August and September (Fig 2), taken from four types of Arctic Ocean habitats: Sea ice (ICE), melt pond water (MW) (pools of open water that form on the surface of sea ice during warmer months), under-ice water (UIW), and deep-chlorophyll maximum water (region under water with maximum concentration of chlorophyll) (DCM).

Analysis

DNA extracted from the water samples was processed, and the sequences generated were used to classify the different types of protists found within each habitat. Stations with many protists in common were called `high-exchange’ stations (Ice 3, 7, 8, and 9) and those with very few protists in common were `low-exchange’ stations (Ice 1, 5 and 6).

What did they find?

Question 1: Do habitats in the Central Arctic Ocean harbor specific, and highly adapted protist communities?

Answer: Yes! Composition of protist communities associated with water column differed considerably from sea ice. Samples from the water column mainly had communities of dinoflagellates and Protalveolata, while those found in sea ice were mainly characterized by diatoms (the most common type of phytoplankton), Cercozoa and golden algae (Fig 2). Sea ice also had the greatest diversity and abundance of unique protists, highlighting sea ice as an important hotspot for protist biodiversity.

Unique protist communities in (top) under-ice water and deep-chlorophyll maximum water and (below) sea ice and melt pond water. Image courtesy: Diatoms (Wikimedia Commons), cercozoa (Flickr), golden algae (Wikimedia Commons), dinoflagellates (Flickr), protalveolata (Nathan Calkins – Calkins, Gary N. ( 1901 ) Marine Protozoa from Woods Hole , Bulletin of the United States Fish Commission, vol.21, Washington, DC : Government Printing Office)

Question 2: Are ubiquitously found protists still partial to a certain habitat?

Answer: Indeed! Although some protists were found in all four habitats, they often showed distinct preferences. The authors suggest that their ubiquitous presence is driven by changes in the environment (such as sea ice melting), as opposed to improved adaptability to various habitats.

Question 3: Does melting of sea ice lead to exchange of protists from habitat to habitat?

Answer: Yes, but with a twist. The researchers studied protist exchange at two time points: August (melting of sea ice) and end of September (onset of freezing). Protists had the highest movement between UIW and DCM during both time points, and this occurred during melting and freezing periods. However, while sea-ice melt reduced the percentage of overall movement of protists from one habitat to another, sea ice formation increased the overall movement, and increased protist diversity.

Significance

Earth’s climate is undergoing a seismic shift, especially in the Arctic Ocean. Sea ice acts as safeguard for thousands of marine micro- and macro-organisms, and climate change threatens the continuing existence of this vast ecosystem. Protists are a key piece of this network, and as a consequence of decreasing sea ice, their natural habitat is vanishing. This study provides an insight into protist endangerment due to climate change, its disturbing direct effect on the rest of the marine food chain and biogeochemical cycles, and the indirect, but potent effect their loss will have on us, the terrestrial species.

 

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 23 hours 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 week 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 weeks 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 3 weeks 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 1 month 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 2 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 2 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 2 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 2 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 3 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 3 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 4 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 4 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 5 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 5 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 6 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 6 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 7 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 7 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
  • by oceanbites 8 months ago
    Today is the day of  #shutdownacademia  and  #shutdownstem  and many of us at the Oceanbites team are taking the day to plan solid actions for how we can make our organization and the institutions we work at a better place
WP2Social Auto Publish Powered By : XYZScripts.com