The Living Carbon Pumps of the World's Oceans: Algal Blooms Attacked by Viruses

Understanding Earth's carbon cycle is a huge part of better understanding climate change. Now, scientists have taken a closer look at the world's global carbon pumps by examining the ocean's phytoplankton.

When scientists refer to the Earth's carbon "pumps," they're talking about global carbon fixation. Organisms and processes can take carbon out of the planet's atmosphere and then "fix" it. Phytoplankton is just one of the species that accomplishes this goal.

Although phytoplankton are tiny, they can be seen from space in the massive blooms that they create, which can reach thousands of kilometers in area. These blooms have the tendency to grow quickly and then disappear suddenly. Intrigued by this, the scientists wanted to find out exactly how much carbon a bloom can fix, and what happens to that carbon when the bloom disappears.

In order to better understand these miniscule organisms, the researchers combined satellite data with field measurements. This allowed them to measure the effect of viruses on phytoplankton blooms on large, open ocean areas. First, the scientists identified a special subset of ocean patches in which currents did not affect the blooms, so that they could just observe biological effects. Then, they traced the bloom's entire life cycle.

So what did they find? The scientists estimated that an algal patch around 1,000 sq km can fix around 24,000 tons of organic carbon. That's equivalent to a similar area of rainforest. Viral infection can quickly wipe out an entire bloom, which means that the ability to observe and measure this process from space may greatly contribute to understanding and quantifying the turnover of carbon cycle and its sensitivity to environmental stress conditions, including marine viruses. In other words, viruses can greatly affect the carbon cycle since they can cause the bloom to die in a short period of time.

The findings reveal that phytoplankton, and viruses, have a huge role to play in the world's carbon cycle. This, in turn, may tell scientists a bit more about how carbon is trapped and then released again, which could have implications for climate change models.