Ocean Acidification May Negatively Impact Diatoms in the Southern Ocean

Ocean acidification can cause a host of issues for species. Now, though, a new study shows that it can also affect tiny creatures called diatoms. Scientists have found that ocean acidification may have negative impacts on diatoms in the Southern Ocean.

"Diatoms fulfill an important role in the Earth's climate system," said Clara Hoppe, one of the researchers, in a news release. "They can absorb large quantities of carbon dioxide, which they bind before ultimately transporting part of it to the depths of the ocean. Once there, the greenhouse gas remains naturally sequestered for centuries."

Scientists have actually assumed in the past that ocean acidification would promote the growth in diatoms. They believed the addition carbon dioxide in the water would have a fertilizing effect. However, it appears that this isn't the case.

"Several times a day, the wind and currents transport diatoms in the Southern Ocean from the uppermost water layer to the layers below, and then back to the surface-which means that, in the course of a day, the diatoms experience alternating phases with more and with less light," said Hoppe.

Under these conditions, the diatoms suffer most from insufficient light when they are in the deeper water layers. This is when they grow more slowly in changing compared to constant light. However, former experiment didn't take this shifting light into account, which greatly affects diatoms' reactions to ocean acidification.

"Our findings show for the first time that our old assumptions most likely fall short of the mark," said Bjorn Rost, one of the researchers. "We now know that when the light intensity constantly changes, the effect of the ocean acidification reverses. All of a sudden, lower pH values don't increase growth, like studies using constant light show; instead, they have just the opposite effect."

The findings reveal that diatoms may be negatively impacted by ocean acidification. This, in turn, could be bad news for the entire ecosystem. Currently, the researchers hope to explore how different algae species reaction to changes in their habitat in order to see which species will benefit from ocean acidification and which will suffer.

The findings are published in the journal New Phytologist.

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