How viruses shape the oceans
Anewly discovered type of virus could play an important role in the ocean’s ability to take planet-warming carbon out of the atmosphere. The tiny plants and animals that live in the sea, called plankton, take carbon out of the air just like trees and plants on land. The newly discovered viruses, which infect plankton and change their function, could play a vital role in this process.
Marine plankton draw carbon dioxide gas out of the atmosphere at the sea surface and lock it away by falling to the deep sea floor when they die. Natural systems that take carbon out of the air and store it are called carbon sinks. The ocean is one of the planet’s most effective carbon sinks, partly because of plankton. Viruses can affect this process by infecting plankton and changing how they work.
Viruses are tiny biological machines that share some similarities with living things but some scientists say they are too basic to truly be considered alive. They contain complex molecules like other lifeforms but they can only reproduce by infecting other living things like animals, plants and even bacteria (see panel). An international team of scientists collected thousands of samples of plankton in seawater from places all over the world. They found signs of infection from thousands of viruses, including many that they’d never seen before.
One group of new viruses was found in places all over the planet. These have been named the after the sailing ship Tara, which was used by the scientists to take the samples.
The team has found that 11 of the viruses they discovered affect how much carbon the plankton take out of the atmosphere. It’s estimated that about one third of all carbon emissions from human activity gets locked up by plankton, so understanding this process better could help us respond to climate change. Overall, the scientists discovered 5,500 new species of virus, suggesting they are more important to ocean ecosystems than previously thought.
How viruses work
Viruses hijack living creatures in order to create copies of themselves. This can affect the behaviour of the host creature and its DNA (the chemical that tells living things how to grow and develop). Every living creature contains microscopic “factories” where its DNA instructions are used to produce various chemicals. A virus works by smuggling its code into a living thing’s DNA, so that the factory produces copies of the virus instead. For example, the coronavirus pandemic was caused by a virus that gets inside human cells (the microscopic units that make up the body) and uses them to reproduce, before breaking out and spreading through the air.