The job of capturing carbon crucial to sustaining life on earth is usually carried out by plants that use sunlight as energy. But light doesn’t penetrate below 656 feet of ocean, so plants can’t do this job. To survive, living cells must convert carbon dioxide into molecules that can form cellular structures or be used in metabolic processes, the scientists said.
Simple, single-celled organisms called archaea that often live in extreme conditions were thought to be responsible for much of the dark ocean’s carbon fixation. But there was evidence that archaea could not account for the total amount of carbon fixation going on there.
“Our study discovered specific types of bacteria, rather than archaea, and their likely energy sources that may be responsible for this major, unaccounted component of the dark ocean carbon cycle,” said study author Ramunas Stepanauskas of the Bigelow Laboratory Single Cell Genomics Center in the Gulf of Maine.
To get a glimpse of what was going on in the dark, the researchers looked at samples from two subtropical gyres, or systems of rotating ocean currents, in the South Atlantic and North Pacific.