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Learn More: Ocean Ecology

"Quite simply, plankton is the foundation of our existence, and all life on Earth depends upon plankton." -The GOES Foundation

Phytoplankton are tiny plants and algae that live in the upper sunlit layer of almost all water bodies on Earth. They serve as the base of the marine food web, and produce oxygen vital to life. Studying this incredibly diverse group is key to understanding the health - and future - of our ocean and life on earth.

What's New
Explore the beauty of phytoplankton
Which phytoplankton are you?
Tiny but important
Wander and drift
Microscopic photosynthetic drifters [more]
Ocean ecology and PACE [more]
Phytoplankton - it's what's for dinner [more]

FAQs

Yes, phytoplankton do have chlorophyll (light-absorbing green pigment within plants), but they also have other pigments that influence how they absorb and scatter light. These other pigments are called accessory pigments. They allow the phytoplankton to efficiently absorb more light, but of different colors (wavelengths) than if they had just chlorophyll pigment. So depending on how much of these pigments they each have, they can override the chlorophyll and actually make them a different color. Also, not only is the pigment content of the phytoplankton important, but also the size and shape. So the way that the light is scattered by the texture, size, and shape of that phytoplankton will also influence the color. So, they're not always green.

Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).
First, if you work with satellite data, you're drier, and you don't get seasick! We do need the ship-based research to ground truth the satellite data. If you think about it from an ocean scientist perspective, it's just two different tools in your tool set. We can go to sea and collect information directly that allows us to develop algorithms - mathematical relationships - that ultimately connect the ocean color measurements that we sense remotely from space with the things that we want to measure in the ocean - for instance, the number and type of phytoplankton in the seawater. But then there are days when we're stuck in front of the computer and dream about the sea, and then we go to sea and dream about being dry and stuck in front of the computer.

Satellite data show us greater coverage geographically of the ocean surface. When we're on a ship, we're only hitting this (tiny) part of the ocean, but the satellite is covering the entire ocean. So ultimately, we get a lot more information from satellites, versus just data from one portion of the ocean when we're sampling on a ship.

Dr. Ivona Cetinić, Ocean Ecologist and Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).
A Trichodesmium bloom in the Coral Sea
A Trichodesmium bloom in the Coral Sea (September 1, 2019). Credit: NASA Earth Observatory.
Yes, it has an impact not only on ocean color (because there are sediments there and it's going to affect the scattering and absorption that we see in the water column) but there have been some studies that have looked at the iron input from those Saharan dust storms into the Gulf of Mexico and the middle of the Atlantic that might actually stimulate things like Trichodesmium (a type of cyanobacterium that likes iron). So that iron that comes from the Saharan Desert will actually stimulate them to grow. So yes, it can have an impact on phytoplankton.

Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).
Karen brevis, magnified 20x
Karen brevis, magnified 20x.
There are. Trichodesmium forms little strands and group together to form colonies (1-10 mm in length). And when you're out at sea - and we've both seen this ourselves - they actually form what we call sawdust on the (ocean) surface and you can see that with the naked eye. Another dinoflagellate, Karenia braves - if there's a high enough concentration of it in a bottle - you can see the little balls swimming around. They're about the size of Alexandrium (another dinoflagellate, 0.018 - 0.045 mm) which you can almost see with the naked eye.

Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).
I grow my own monocultures (= one species only) of various types of phytoplankton in one of our labs here at Goddard. Basically, every two to three weeks, I make fresh growth mediums (dissolved vitamins, minerals, and nutrients - all they need to survive - mixed in with seawater), and I transfer the phytplankton cultures to the new medium. After a while the cells use up all the nutrients and start to die, just like in the ocean, so you have to replenish their nutrients. So every few weeks I have to put them in new seawater with nutrients. So far they haven't needed any waves to survive in stationary flasks.

There are places where you can buy starter cultures and grow them yourself. I did see an advertisement for bioluminescent phytoplankton (organisms that produce their own light). Otherwise, when scientists collect phytoplankton to make into a monoculture, they have to go out to sea and individually isolate different cells and then start growing them.

Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).
Phytoplankton and blue-green algae blooms in the Baltic Sea
Phytoplankton and blue-green algae blooms in the Baltic Sea (July 23, 2018). More frequent and massive blooms, combined with warming seas due to climate change, are making it harder for fish and other marine life to thrive in this basin. Credit: NASA Earth Observatory.
There are many studies looking at the impact of climate change on the oceans, and ultimately on ocean life. Many of them are looking at the impact climate change has on phytoplankton diversity and abundance. Scientists have seen over the last few years changes in the way that the land interacts with the ocean - increases in land-based input through rivers, and processes associated with agriculture, and so on - which we see results in more abundant blooms in the coastal ocean, especially harmful algal blooms (plankton blooms that have the capacity to cause physical injury, or other negative outcomes, when they reproduce quickly and have high concentrations in seawater).

Dr. Ivona Cetinić, Ocean Ecologist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters (15-May-19).