Oceans have grown more acidic as rising levels of carbon dioxide have filled the Earth’s air, prompting a trio of San Francisco State University researchers to investigate whether marine plankton will continue to produce much of the globe’s oxygen as its wet world grows more hostile.
Massive blooms of microscopic phytoplankton are sometimes visible from space. Unlike other types of tiny, fast-growing plankton, phytoplankton grow using energy from the sun.
Phytoplankton feed ocean ecosystems, fighting global warming by turning carbon dioxide into protective shells that are eaten by other creatures or sink to the sea floor.
“They’re bringing the carbon dioxide down into the deeper water,” San Francisco State University biology professor Ed Carpenter said, “so they’re helping to slow global warming.”
Like plants, phytoplankton release oxygen into the air, and they produce half of the world’s breathable oxygen, Carpenter said.
But the world’s air is becoming so saturated with carbon dioxide that oceans have grown increasingly acidic since the Industrial Revolution, Carpenter said. Ocean acidity could rise by the end of the century because of rising carbon dioxide levels in the atmosphere, said Carpenter, who added that increasingly acidic water can burn through carbon shells that protect marine creatures.
To see whether plankton can survive and thrive in increasingly acidic water, Carpenter and two other researchers secured $1.2 million from the U.S. National Science Foundation to conduct long- and short-term experiments in the coming years.
One set of the short-term experiments will compare plankton growth in conditions that simulate today’s ocean conditions with conditions that simulate those expected by 2100, said SF State biology professor Jonathon Stillman, who is working with Carpenter on the project at a laboratory in Tiburon.
Long-term experiments, on the other hand, will monitor clouds of rapidly multiplying phytoplankton as it evolves in acidifying water over 700 generations, according to Stillman. That will test whether plankton evolve defenses against the changing ocean conditions expected in the coming 93 years.
“If there’s going to be an adaptive response,” Stillman said, “we should see it by the end of two years.”
The research team began preparing for the experiments last summer, according to Stillman.