They’re small, but they’re mighty. From producing oxygen we breathe to soaking up carbon we emit to feeding fish we eat, tiny phytoplankton are a crucial part of ocean ecosystems and essential to life as we know it on Earth. To give us a new view of these extraordinary aquatic organisms, NASA is launching a satellite in early 2024.
Instruments on the PACE (short for
Plankton, Aerosol, Cloud, and ocean Ecosystem) satellite will peer down at the
ocean and collect data on the colors of light reflecting off it, telling us
where different types of phytoplankton are thriving.
The Ocean Color Instrument on PACE will be
able to observe more than 100 different wavelengths, and is the first scientific
satellite to do so daily on a global scale. This "hyperspectral"
instrument will make it possible to identify phytoplankton by species for the
first time from space.
Ivona Cetinić, the Science Lead for Ocean Biogeochemistry for PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) describes the weird, wonderful and important world of phytoplankton and why it's important for the PACE mission to study these tiny creatures. Credits: NASA's Goddard Space Flight Center
This video can be downloaded for free at NASA's
Scientific Visualization Studio.
Phytoplankton and Photosynthesis
Phytoplankton are tiny organisms
that float on the surface of the ocean and other water bodies. Like land-based
plants, phytoplankton use photosynthesis to absorb sunlight and carbon dioxide
and generate oxygen and carbohydrates, which are carbon-filled sugars. These
sugars make phytoplankton the center of the ocean food web: They nourish larger
animals – from zooplankton to shellfish to finfish – that are then eaten by
even larger fish and marine mammals. The creation of those sugars from sunlight
is called primary production.
Even though phytoplankton make up
less than 1% of the total biomass on Earth that can photosynthesize, they
deliver about 45% of global primary production. Without phytoplankton, most
oceanic food webs would collapse, which would be devastating for both marine
life and humans who rely on fish for food.
The tiny organisms provide more
than just nutrients. Through photosynthesis, phytoplankton create oxygen that
is released into the ocean and atmosphere. In fact, since they began
photosynthesizing over 3 billion years ago – more than two billion years before
land plants and trees – phytoplankton have made about 50% of all the oxygen
that has been produced on Earth.
Photosynthesis gives them a key
role in the global carbon cycle as well, as they soak up carbon dioxide from
the atmosphere. What phytoplankton do with that carbon depends on the species.
“Like plants on land, phytoplankton
are highly diverse,” said Ivona Cetinić, a biological oceanographer in the
Ocean Ecology Lab at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Each of these diverse species has different characteristics that allow them to
take on different jobs in Earth’s carbon systems, she said.
Phytoplankton like Emiliana
huxleyi incorporate carbon into their shell-like outer coating. When
they die, the shells sink and sequester the carbon in the ocean depths. Other
phytoplankton species fit a certain niche for picky eaters like oysters, which
only eat phytoplankton of a certain size. Still other species of phytoplankton
may capture carbon through photosynthesis, where it then remains on the ocean
surface until the organisms decompose, releasing the carbon back into the
atmosphere as carbon dioxide.
“I hope that PACE, once it gives us a view of ocean phytoplankton diversity, can tell us so much more about global carbon flow in oceans, now and in the future,” Cetinić said.
“Without phytoplankton, we may not be able to breathe or eat sushi,” said Aimee Neeley, a NASA Goddard oceanographer. Large green blooms of phytoplankton swirl in the dark water around Gotland, a Swedish island in the Baltic Sea. Credits: USGS/NASA/Landsat 7
Phytoplankton in the Cold
Even in colder waters at higher
latitudes, phytoplankton are crucial to ocean life. In polar regions,
phytoplankton blooms – when the organisms grow and multiply in vast numbers
visible from space – can follow the cycle of sea ice melt.
When sea ice cover recedes,
sunlight can reach the surface of the ocean and the phytoplankton that float on
it, allowing them to photosynthesize and thrive after a long period of being
covered. This produces fuel for other species. Polar species from clams and
krill all the way up to walruses and whales rely on these timely blooms for
their food sources.
“An alteration of the timing of the
blooms impacts the entire ecosystem,” said Aimee Neeley, a biological
oceanographer at NASA Goddard.
As the timing and extent of sea ice
retreat changes in a warming climate, PACE will be able to track changes to the
timing of blooms, providing insights into the wider impacts to the ecosystem.
Identifying Harmful Phytoplankton
Not all phytoplankton are
beneficial for ecosystems. Some species can produce toxins that are dangerous
for humans or other marine species. These harmful algal blooms can disrupt
ecosystems as well as daily life for people near coasts, lakes, and rivers.
Blooms of cyanobacteria, for example, can spoil drinking water and recreational
water use with the toxins they generate.
Scientists have been using some
satellite data to track and monitor these blooms and the conditions that cause
them. PACE should make it easier to decipher these species and conditions,
allowing people to develop ways to mitigate the impacts and prevent future
blooms.
“Not all phytoplankton create
harmful algal blooms, so if we can use the satellite data to better separate
harmful from non-harmful blooms, that would be helpful for water managers and
scientists that are trying to understand phytoplankton communities in a
region,” said Bridget Seegers, an oceanographer at NASA Goddard.
PACE will not be the first
satellite to let us see phytoplankton from space. The mission is a successor to
missions like Terra, Aqua, Landsat, and SeaWiFS (the Sea-viewing Wide
Field-of-view Sensor), which have gathered data on phytoplankton since the
1990s. PACE, which is being assembled at and managed by engineers at NASA
Goddard, will significantly expand our ability to distinguish and track
phytoplankton every day, all over the planet.
“Hopefully, the hyperspectral nature of the Ocean Color Instrument will allow us to better tease apart the phytoplankton types from each other and from non-phytoplankton particles,” Neeley said. “To me, the opportunities for research will be endless.”
By Erica McNamee
NASA's Goddard Space Flight Center, Greenbelt, Md.
Source: NASA Wants to Identify Phytoplankton Species from Space. Here’s Why. | NASA
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