Climate Change Altering Earth's Oceanic Food Chain

Climate change is having an impact on organisms across the globe. Yet it may also be affecting our oceans in a big way through the alteration of tiny bacteria. Scientists have discovered that changing conditions could be weeding out select strains for survival, which could be altering the entire oceanic food chain.

There are both winners and losers when it comes to climate change. Some creatures thrive in the new conditions while others slowly disappear from ecosystems. In the case of the oceanic food chain, though, it turns out that nitrogen-fixing cyanobacteria may be less diverse in the future.

"This may have all kinds of ramifications for changes in ocean food chains and productivity, even potentially for resources we harvest from the ocean such as fisheries production," said David Hutchins, professor at the USC Dornsife College of Letters, in a news release.

In order to conduct this study, the researchers studied two major groups of nitrogen-fixing cyanobacteria. More specifically, they examined Trichodesmium, which forms large floating colonies big enough to see with the naked eye in the open ocean, and Crocosphaera, which is also abundant but is a single-celled microscopic organism.

What did they find? While previous research showed that these two types of cyanobacteria should be some of the biggest "winners" of climate change, it turns out that these studies only examined one or two strains of the organism. Surprisingly, the scientists discovering that some strains actually don't thrive in conditions that will be present in a future "greenhouse" Earth.

"It's not that climate change will wipe out all nitrogen fixers; we've shown that there's redundancy in nature's system," said Hutchins in a news release. "Rather, increasing atmospheric carbon dioxide changes specifically which nitrogen fixers are likely to thrive. And we're not entirely certain how that will change the ocean of tomorrow."

The findings have huge implications for the future of the world's oceans. These small organisms make up the base of the oceanic food chain. A change in their composition could, in turn, alter which species are present higher up the food chain.

The findings are published in the journal Nature Geoscience.