Climate Change Could Alter Key Ocean Bacteria: Study

Climate change could put a type of oceanic bacteria into evolutionary overdrive in a way that could pose a threat to its long-term survivability and its important role in the food chain, according to a study published on Tuesday.

The research published in the journal Nature Communications focuses on trichodesmium, a cyanobacteria found in tropical and subtropical waters such as the Red Sea, the Great Barrier Reef off Australia's coast, areas around Hawaii and the Caribbean.

Trichodesmium is important to the ocean's food chain because it converts atmospheric nitrogen gas into biologically usable forms of nitrogen that other organisms, such as phytoplankton, can use. An abundant supply of nitrogen is important to support a wide variety of marine life, from algae to whales.

A team led by researchers at the University of Southern California found that trichodesmium generates more nitrogen and reproduces faster when exposed to the high levels of carbon dioxide that are expected to exist in the world's oceans in the year 2100 due to climate change, according to the university.

But even though this evolutionary adaptation may seem beneficial for certain parts of the ocean's ecology, it could harm the bacteria in the long term by leading them to gobble up all their available resources of the nutrients phosphorous and iron, the study indicated.

In a surprising discovery, the researchers found trichodesmium continues to reproduce quickly and generate a lot of nitrogen even when placed back in an environment with lower levels of carbon dioxide.

This suggests that if climate change creates an evolutionary adaptation in the bacteria, this alteration may persist even if global action is taken to reverse climate change.

The researchers said they produced their results in a laboratory and that in trichodesmium's natural environment, certain factors may mitigate the changes in the bacteria seen in the lab test.

Even so, said David Hutchins, professor of biological sciences at the University of Southern California, the evolutionary alterations that his team found in the lab when exposing trichodesmium to high levels of carbon dioxide are not a healthy development for the organism.

"The last thing you want is to be stuck with these high growth rates when there aren't enough nutrients to go around. It's a losing strategy in the struggle to survive," he said in a statement.