Climate Change May Impact Vital Ocean Chemical Cycles

Warming ocean temperatures may hamper vital ocean chemical cycles of carbon dioxide, nitrogen and phosphorus, according to a new study.

Researchers from the U.K.’s University of East Anglia showed that warming ocean temperatures impacted chemical cycles in plankton – free-floating organisms that play an important role in the ocean’s carbon cycle by removing half of the carbon dioxide in the atmosphere and storing it underwater.

“[Plankton] also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries, so it is incredibly important for food security,” lead researcher Dr. Thomas Mock said.

Based on a global ecosystem model they created to track the world’s ocean temperatures, 1.5 million plankton DNA sequences and biochemical data, the researchers found that "temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before," Mock said.

A key finding was that marine micro-algae don't produce as many ribosomes, a form of molecular protein builders, in warmer temperatures as they do in cooler temps.

"They are rich in phosphorous and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorous, increasing the demand for nitrogen in the oceans,” Brock said. "This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria, which fix atmospheric nitrogen."

While previous studies have drawn a link between plankton and global warming, this one, published in the journal Nature Climate Change, was the first to show a direct connection between warm water temperatures and chemical cycles, Mock said.

"Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity,” Mock said. “But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before."