//
you're reading...

Biodiversity

Phytoplankton: Small cells with a big impact

Citation: Kulk, G., et. al., 2020. Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades. Remote Sensing 12, 826. https://doi.org/10.3390/rs12050826

The power of phytoplankton

Phytoplankton make up less than 1% of the photosynthetically active biomass on Earth, yet they are responsible for half of the total global net primary production. Primary production is the rate at which phytoplankton remove carbon dioxide from the atmosphere and convert this carbon dioxide into sugar. This process is called photosynthesis. Lucky for us humans, oxygen is produced from photosynthesis so we get our oxygen from the ocean! Pretty neat.

An example of a phytoplankton community in the ocean. Cells come in many different shapes and sizes! Photo credit: Richard Kirby, Smithsonian

Primary production in the ocean is one of the largest fluxes of carbon on the planet. Therefore, measuring primary production (PP) is of great interest to the scientific community. Production rates are affected by physical parameters in the water such as temperature, light and nutrients. Phytoplankton need light for photosynthesis and nutrients for various cellular processes. The ocean has already experienced environmental change, such as increases in sea surface temperature, sea ice melt and enhanced precipitation. These physical changes will affect nutrient concentrations in the sun-lit layer of the ocean, where phytoplankton thrive. Therefore, it is important to monitor how physical changes affect primary production rates.

Global net primary productivity across the ocean basins. Image credit: earthobservatory.nasa.gov

Primary production is measured in different ways. Scientists can either collect direct measurements from water sampling or they can use satellite-based methods. Wonder how we can use satellites to look ay microscopic organisms from space? Well, all phytoplankton use a pigment known as chlorophyll-a to help them harvest energy from the sun during photosynthesis. Wavelengths of chlorophyll-a can be picked up by satellites in space and are used to get an estimate of global phytoplankton biomass. In this study scientists used a database of chlorophyll-a concentrations and surface light measurements in the ocean to establish global primary production and its changes over the last two decades.

How did they do it?

The scientists obtained monthly surface chlorophyll a concentrations from 1998 to 2018 from the European Space Agency Ocean Color Climate Change Initiative project and separated into different oceanic regions. For the primary production model, the authors used a model that can separate chlorophyll-a wavelengths from other light that is reflected off the ocean surface and they were able to look at how chlorophyll-a changed with depth. This model incorporates changes in photosynthesis as a function of light. The scientists retrieved photosynthesis-irradiance curve parameters from a global database. A photosynthesis-irradiance curve is a graphical representation of the relationship between photosynthesis and available sunlight. Since photosynthesis requires light, there is a positive relationship between these two variables; however, the exact relationship and thus parameters, depends on physical properties such as temperature and nutrients. Parameters for the photosynthetic-irradiance curve change based on location in the ocean so the scientists turned to a database to incorporate different parameters in their model. The database covers 53 provinces and represents about 97% of the world’s oceans. So by combining measurements and parameters from the database, the scientists were able to understand how various photosynthetic parameters affected the sensitivity of primary production over two decades from 1998 to 2018.

What did they find?

Using the models they created with photosynthesis versus light parameters, the scientists found that summer was the most productive (11.6-12.9 gigatons of carbon over three months). For comparison purposes, the Amazon rainforest fixes 86 gigatons of carbon per year. On more regional scales, the Pacific Ocean had the highest production and general trends in production rates across all regions varied considerably between 1998 and 2018. There was a large variability in global production on an annual scale where production increased during some years (1998-2003), was stable during others (2003-2011), and decreased at other times (2011-2015). The variations in global primary production were associated with trends in the El Niño-Southern Oscillation and Atlantic Multidecadal Oscillation climatic events. These climatic events work on larger scales and affect wind patterns and currents. Changes in wind and currents can affect nutrient conditions and thereby affect phytoplankton growth and production rates.

Satellite image of a phytoplankton bloom in the Southern Ocean. Image credit: NASA

What is the point of this?

Phytoplankton production rates are difficult to measure directly and can vary significantly between methods. Since phytoplankton production is a key process in global carbon cycling, it is important to understand the environmental parameters that affect the ability of phytoplankton to take in carbon dioxide from the atmosphere. This study is the first to combine high-quality, multi-sensor ocean color observations over two decades to examine the magnitude and variability in marine primary production on a global scale. The model developed in this study led to a more accurate assessment of global annual primary production and its trends over the past 20 years. Modeling these production rates using high resolution models is a good approach to estimate how rates will change under continued global environmental change.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 3 weeks 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 1 month 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 3 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 3 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 3 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 3 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 4 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 4 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 5 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 5 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 5 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 5 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 6 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 6 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 7 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 7 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 8 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 9 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 9 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 9 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
WP2Social Auto Publish Powered By : XYZScripts.com