Ocean Heating Poses Risk to Key Photosynthetic Microbes

(MENAFN) Rising ocean temperatures threaten to severely impact populations of Prochlorococcus, microscopic organisms responsible for "5% of all global photosynthesis," with their productivity potentially falling by 37% worldwide under extreme climate conditions.

New findings, published Monday in Nature Microbiology, an exclusively online journal, indicate that these minuscule marine microbes can endure water temperatures only up to 86F (30C) before their reproduction rates "crash dramatically," contrary to earlier scientific assumptions.

The University of Washington-led study discovered that these organisms reproduce most effectively in waters ranging from 66F-84F (18.8C-28.8C), but when temperatures exceed 86F, "cell division rates plummet to just one-third of optimal levels."

Climate projections suggest that within 75 years, ocean temperatures in tropical and subtropical regions will surpass this critical threshold.

Under moderate warming scenarios, Prochlorococcus productivity could decline by 17% in tropical waters and 10% globally.

In high-warming scenarios, tropical declines may reach 51%.

"Their burnout temperature is much lower than we thought," said Francois Ribalet, who led the study, which examined 800 billion cells over 150,000 miles (241,401 kilometers) during nearly 100 research cruises across a decade.

Researchers emphasized that Prochlorococcus form "the foundation of marine food webs," sustaining life from tiny sea creatures to whales across more than 75% of ocean surface waters.

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