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Scientists: Microbial Biodiversity Ten Times Higher Than Previous Estimates

Coral Reef Study Reveals Surprising Findings

The schooner Tara.  ©Yohann Cordelle/Wikimedia CC BY 3.0
The schooner Tara. ©Yohann Cordelle/Wikimedia (CC BY 3.0)

An ambitious, two-year study of coral ecosystems known as the Tara Pacific expedition was recently completed, offering a new look at the biodiversity of coral reefs and a reference point for studying the biology of coral reefs during the modern period of the Anthropocene. The study’s findings were published in June 2023 in Nature Communications.

The project’s extensive sampling and research were conducted aboard the Tara, a schooner after which the expedition was named. While at sea, the team sampled the coral ecosystems of thirty-two islands in the Pacific Ocean and ocean surface waters at 249 locations. This resulted in the collection of nearly 58,000 samples, using “various approaches.”

As reported by, a team of seventy scientists from eight nations were involved in the study with the project’s scientific coordinator, Dr. Christian Voolstra, professor of genetics of adaptation in aquatic systems at the University of Konstanz. The team reported a surprising conclusion from their findings: “We have been completely underestimating the global microbial biodiversity,” says Dr. Voolstra. Indeed, the current estimate of planetary microbial biodiversity—of around five million bacteria—is underestimated by nearly a factor of ten, he says. In other words, the planet may have ten times more biodiversity than previously thought.

How can this be? According to the news brief, coral reefs are the most “biologically diverse marine ecosystem on Earth.” Even though they cover just 0.16% of the world's oceans, they house about “35% of known marine species.” By using a “genetic marker-based data set,” the Tara Pacific researchers discovered that “all of the globally estimated bacterial biodiversity” can be found in the microorganisms of coral reefs.


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