Climate Change Threatens Cyanobacteria
One of the world’s most common organisms is threatened by rising sea temperatures. The amount of the most common type of cyanobacteria (prochlorococcus) is at risk of being halved unless climate change is slowed down.
Text: Arvid Wiclander Mellgren
A new study shows that cyanobacteria decline sharply when the surface temperature exceeds 28 degrees Celsius. According to climate forecasts, large areas of the ocean are at risk of becoming continuously warmer than this in the future. The new study predicts that, in a worst-case scenario, the species could be halved in number by 2100.
As the species is the most common type of cyanobacteria, it is important for the food chain. Monika Quinones Winder, professor of marine ecology at Stockholm University, explains:
“This bacterium dominates in the tropical and subtropical parts of the ocean. It plays a very important role in producing energy, i.e. food for other species,” she tells Deep Sea Reporter.
Cyanobacteria are also important for oxygen levels in the ocean and atmosphere. They are the most common photosynthetic organisms on Earth. “You could say that cyanobacteria are tiny plants.
“They account for one-fifth of the Earth’s oxygen production”, says the professor.
Monika Quines Winder believes that other species will be able to at least partially replace the bacterium’s role as an oxygen producer, but Prochlorococcus’ role as an energy producer in the food chain is even more important.
Irrevocable threshold
One of the researchers behind the study published in the journal Nature, marine biologist François Ribalet, is concerned about the consequences this could have.
“We are crossing a threshold that may be irreversible. I don’t want to be dramatic, but that’s what our data tells us,” he told SVT Nyheter.
The study provides an estimate of the future, but cannot say for sure exactly how things will turn out. In the best-case scenario, the researchers hope that the bacteria will be able to adapt to some extent and cope with higher temperatures. In that case, the species could decline by only 17 percent, instead of being halved in number.
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