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High CO2 Levels in Water Can 'Dissolve' Starfish, Scientists Say

Scientists in Scotland have warned that “pulses” of carbon dioxide could have a potentially disastrous effect on marine ecosystems. 

A team of researchers from Glasgow University and Ediburgh’s Heriot-Watt University tested the effects of high levels of CO2 gas, at Loch Sween on Scotland’s west coast. 

They pumped water enriched with CO2 into chambers placed over the coralline algal ecosystem to see how the ecosystem responded to short-term exposure to the gas. 

And they found that “calcified organisms” like coralline algae were very negatively impacted — with starfish even being caused to dissolve. 

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It’s the first time scientists have tested how an entire marine ecosystem responds to CO2, with previous tests having focussed on the effect large amounts of the gas have on individual plants and animals. 

“We found that there was a rapid, community-level shift to net dissolution, meaning that within that community, the skeletons of calcifying organisms like starfish and carline algae were dissolving,” said Heidi Burdett, a Heriot-Watt University research fellow. 

“If you think of pulses of carbon dioxide being carried on the tide to a particular site, it’s like a flash flood of carbon dioxide,” she added. 

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The team monitored the ecosystem before, during, and after its exposure to CO2. 

They also found that recovery in the exposed sites was comparatively slow, raising concern about how well these ecosystems can “bounce back” from the damage.

Scientists, while acknowledging that more research is needed, said it suggested carbon dioxide from industrial sites and land run-off could cause irreparable damage if it enters the marine environment. 

These coralline algal ecosystems can be found in all the world’s coastal oceans, but are particularly common on Scotland’s west coast. 

Read more: Why You Should Probably Never Eat Seafood Again

“These beds have significant ecological and economical value,” Burdett continued. “In Scotland, they act as nurseries for important catches like scallops, cod, and pollock.” 

Burdett warned that the findings could suggest policymakers need to take marine ecosystems into account when deciding the locations of new fish farms, forestry, or carbon capture sites. 

“We should be looking at what marine ecosystems are nearby, and the potential for those ecosystems to be impacted by the new activities as a whole, rather than focusing on the impact on individual organisms,” said Burdett. 

The research comes as part of Heriot-Watt’s Year of the Sea programme, which focusses on marine research in Scotland, but also on its global campuses. 

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“We need a much greater understanding of what’s happening in our lochs, rivers, seas, and oceans,” added Burdett, whose research was published in the Marine Progress Ecology Series. 

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