These microscopic floating algae grow within the first metres deep of the ocean , which receives enough sunlight for them to carry out photosynthesis, just as plants on land do. They feed small, animal-like zooplankton, such as krill, which are then eaten by everything from sardines to manta rays and even multi-ton whales.
Trees, shrubs, grasses and other land plants are often thought of as our main source of oxygen, but phytoplankton generate as much oxygen as all of these plants combined. Without plankton, the concentration of CO2 in our atmosphere would be even higher, and its effects, like rising sea levels and shifting weather patterns, would be even stronger.
As the concentration of greenhouse gases in our atmosphere increases, so does the amount of CO2 in our oceans. WWF is collecting postal codes so we can send you news and invitations most relevant to your area.
Plankton make up 95 per cent of ocean life Whales, sharks, seals and fish might be the most conspicuous marine creatures, but they make up a very small part of the biomass in our oceans. But our increasing emissions are harming them As the concentration of greenhouse gases in our atmosphere increases, so does the amount of CO2 in our oceans. Like other plants, phytoplankton take in carbon dioxide and release oxygen.
Phytoplankton rely on nutrients found in their surroundings, such as phosphate, nitrate, and calcium, to thrive. In addition to phytoplankton and zooplankton, two even smaller kinds of plankton can be found floating in the sea. Bacterioplankton are bacteria and virioplankton are viruses. Plankton can be found in saltwater and freshwater. One way to tell if a body of water has a large plankton population is to look at its clarity. Very clear water usually has less plankton than water that is more green or brown in color.
While plankton populations are needed for thriving marine ecosystems, too many plankton in one area can create a serious environmental problem. These temporary conditions can cause high fish mortality and other damage to the marine ecosystem. Contaminated fish that are caught and served to people may also cause illness and even death. Because the aquatic food chain depends so heavily on plankton, the survival of these tiny plants and animals is essential for healthy marine ecosystems.
Climate change and rising sea temperatures pose serious risks to plankton populations. Department of the Interior Climate Science fellow whose research interests include the role of plankton in the marine food web.
The more that scientists like Corradino understand how to protect these critical marine species, the more likely it is that their research will help creatures further up the food chain survive threats such as climate change. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.
Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. Often, reservoirs receive a huge amount of nitrogen and phosphorous runoff from fertilizer use in agricultural areas, which creates the perfect conditions for diatoms to bloom in the standing water behind a dam.
Plus, thanks to human impacts like fertilizer runoff, phytoplankton have shown up in places where they have had some not so desirable effects. Phytoplankton are responsible for bringing new energy into the ocean by converting sunlight into energy and using it to grow. This is critical since all of the other organisms in the ocean are eating each other, essentially recycling the energy and carbon that phytoplankton have brought in from the sun.
Without phytoplankton bringing in new energy, the total amount of biological energy in the ocean would slowly decrease over time, collapsing entire marine populations along the way. First, they can be directly eaten , usually by slightly larger zooplankton — which in turn serve as food for even larger zooplankton and eventually fish.
In fact, zooplankton grazing on phytoplankton is an extremely important population control. When nutrients become abundant and a bloom occurs, phytoplankton populations could just keep growing until they run out of nutrients. However, zooplankton typically bloom in the following days because suddenly there is a feast of phytoplankton available for them. Thus, zooplankton typically eat enough phytoplankton to the point that their population is returned to pre-bloom numbers, and the zooplankton begin to die off as well as their feast is exhausted.
The second way that phytoplankton can contribute to the marine food chain is that they can die — either from growing old or from running out of nutrients and starving.
When this happens, they release all of the organic carbon and nutrients that their cells contained into the water, making it available for bacteria to munch on. These bacteria then grow and are themselves eaten by zooplankton, which in turn provide a food source for small fish and other creatures low in the marine food chain. The recycling of phytoplankton by bacteria is known as the microbial loop. The result, across an ocean-wide scale of phytoplankton fixing carbon dioxide, is that they have a huge impact on how carbon moves between the atmosphere and ocean.
But the story behind what happens to that carbon once phytoplankton pull it into the ocean is more complicated than simple removal from the atmosphere. This carbon dioxide is still dissolved in the ocean, which serves as something of a buffer to prevent it from being regurgitated to the atmosphere where it can contribute to climate change.
However, the ocean can only hold so much carbon dioxide before it either mixes it back into the atmosphere or begins to turn acidic.
On the other hand, not all of the carbon that phytoplankton take up from the atmosphere is returned to where it came from. Some phytoplankton cells can sink quickly to the bottom of the ocean and become buried in the seafloor without being broken down by bacteria.
This is where diatoms and coccolithophorids are particularly important. Their shells make them harder for zooplankton to graze on and relatively heavy when they die, which means they can sink faster so that bacteria have less time to break them down. In addition, the silica and calcium carbonate shells can also make it harder for bacteria to access the organic carbon inside the shells, increasing the chances that it will be buried rather than converted back to carbon dioxide.
Exactly how much organic carbon is buried versus converted back to carbon dioxide is a major question of scientific research, but a good estimate is that only two percent or less of phytoplankton carbon is buried without returning to the atmosphere.
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