OSU study: Parasitic arsenic cycle shows impact of warmer oceans

A newly discovered parasitic cycle, in which ocean bacteria keep phytoplankton on an energy-sapping treadmill of nutrient detoxification, may offer a preview of what further ocean warming will bring, Oregon State University researchers say.

The research, conducted by OSU scientists in the Sargasso Sea near Bermuda, also may explain how the bacteria, SAR11, came to be so prolific.

In large bodies of water, plankton are the collection of organisms unable to swim against the current.

Phytoplankton refers to the autotrophic, or self-feeding, components of the community – the ones that can produce, often via photosynthesis, organic compounds like fats, proteins and carbohydrates from substances in their environment.

Already, in many of the vast, warm regions of the ocean, phytoplankton must deal with the challenge of discriminating between phosphate, a scarce nutrient essential for cell growth, and arsenate, which is chemically similar but toxic.

“Many phytoplankton, including the most common phytoplankton type in warm oceans, Prochlorococcus, detoxify arsenate by adding methyl groups,” explains Kimberly Halsey, a microbiology researcher at Oregon State University and a co-author on the study.

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