Cyanobacteria forming ‘the lungs of the ocean’ are under pressure

It is the smallest and at the same time most common oxygen -producing organism on earth: Prochloroccus. The cyanobacteria occurs in 75 percent of the oceans that are lit by sunlight – the ice -covered waters therefore do not count. Especially in tropical and subtropical oceans the microbe is ramping, but the question is for how long. According to an American model study in Nature Microbiology Can the Prochloroccus-Production will decrease by more than 50 percent in the coming 75 years. And that is worrying, because the cyanobacteria is at the basis of the marine food chain.

Microscopically small plankton lives in the upper layer of oceans and, thanks to photosynthesis, ensures the production of organic carbon: an essential source of food for other underwater life. One of the protagonists is the micrometer -sized Prochloroccusthat can easily adapt to various circumstances. For that reason it is always assumed that the cyanobacteria would benefit from warming oceans and even advance towards the Poles. But apart from a few Labexperiments, there has never been really extensive research into the consequences of warming up for vegetable plankton.

Ninety research scruits

The American microbiologists wanted to change that. During ninety research cruises for ten years, they sampled 200,000 square kilometers of ocean surface and looked at, among other things, the relationship between cell division of Prochloroccus And temperature. For example, it turned out that the division in the event of warming is initially faster, until a threshold value is achieved: above 28 degrees Celsius the speeds plead and around 31 degrees Celsius the divisions go just as slow as at 19 degrees under the freezing point.

Zoom in

That doesn’t mean that Prochloroccus-Growth at those temperatures is impossible, the authors rush to say: some communities may be better adapted to the heat. But an increasing growth rate at 28 degrees Celsius or more seems very unlikely.

Based on that information, the researchers developed a computer model in which they assume a warming of 1.9 and 3.8 degrees Celsius to 2100 respectively (based on commonly used CO₂-Moet scenarios) and a decrease in food availability in the oceans. The latter would in theory in the advantage of Prochloroccus being able to work because the cyanobacteria thrive in nutrient -poor conditions.

Decrease in tropical waters

Nevertheless, the model predictions show that Prochloroccus-Between 2090 and 2100, with 17 to 51 percent will decrease in tropical waters, depending on the scenario. And even if there is an extension of the area towards the Poles at the same time, worldwide production will still fall by 10 to 37 percent. This is not only disadvantageous for the cyanobateries themselves, but also for species higher in the food chain, including fish. Because even if other plankton species will replace it, the carbon cycle will be due to a substantial decrease of Prochloroccus Change radically – with all kinds of unknown consequences.

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