Study: CO2 causes Starfish to Dissolve

Guest essay by Eric Worrall

Dr. Heidi Burdett has published a study which claims intense CO2 shocks cause starfish and coraline algae to dissolve. The study has implications for siting carbon capture and storage facilities.

Carbon dioxide ‘pulses’ threaten Scotland’s coralline algal reefs

Scotland’s marine ecosystems may be more sensitive to carbon dioxide than previously thought, and could be damaged irreparably by the CO2 ‘pulses’ created by industrial activities, land run off or natural tidal processes.

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Dr Heidi Burdett, a research fellow at Heriot-Watt University’s Lyell Centre for Earth and Marine Science and Technology, said: “Coralline algal ecosystems can be found in all the world’s coastal oceans and are particularly common along the west coast of Scotland. Since coralline algae are highly calcified, we knew they would probably be quite sensitive to CO2.

“These beds have significant ecological and economical value: in Scotland, they act as nurseries for important catches like scallops, cod and pollock.

“We found that there was a rapid, community-level shift to net dissolution, meaning that within that community, the skeletons of calcifying organisms like star fish and coralline algae were dissolving.

“If you think of pulses of carbon dioxide being carried on the tide to a particular site, it’s like a flash flood of CO2.

“Our continued monitoring of the site directly after the CO2 exposure found recovery was comparably slow, which raises concern about the ability of these systems to ‘bounce back’ after repeated acute CO2 events.”

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“If a local authority or government agency is deciding the location of a new fish farm, forestry or carbon capture site, 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.

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Read more: https://www.hw.ac.uk/about/news/carbon-dioxide-pulses-threaten-scotland-s.htm

The abstract of the study;

Community-level sensitivity of a calcifying ecosystem to acute in situ CO2 enrichment

Heidi L. Burdett, Gabriela Perna, Lucy McKay, Gemma Broomhead, Nicholas A. Kamenos

ABSTRACT: The rate of change in ocean carbonate chemistry is a vital determinant in the magnitude of effects observed. Benthic marine ecosystems are facing an increasing risk of acute CO2 exposure that may be natural or anthropogenically derived (e.g. engineering and industrial activities). However, our understanding of how acute CO2 events impact marine life is restricted to individual organisms, with little understanding for how this manifests at the community level. Here, we investigated in situ the effect of acute CO2 enrichment on the coralline algal ecosystem—a globally ubiquitous, ecologically and economically important habitat, but one which is likely to be sensitive to CO2 enrichment due to its highly calcified reef-like structures engineered by coralline algae. Most notably, we observed a rapid community-level shift to favour net dissolution rather than net calcification. Smaller changes from net respiration to net photosynthesis were also observed. There was no effect on the net flux of DMS/DMSP (algal secondary metabolites), nor on the nutrients nitrate and phosphate. Following return to ambient CO2 levels, only a partial recovery was seen within the monitoring timeframe. This study highlights the sensitivity of biogenic carbonate marine communities to acute CO2 enrichment and raises concerns over the capacity for the system to ‘bounce back’ if subjected to repeated acute high-CO2 events.

Read more (Paywalled): http://www.int-res.com/abstracts/meps/v587/p73-80/

Sadly the study is paywalled, so we don’t get to learn how CO2 enriched the test water was. If Heidi was attempting to simulate an industrial release or maybe a volcanic eruption, the answer is likely “quite a lot”.

There are studies which suggest many calciferous organisms are highly resistant to elevated CO2. Some calciferous species have demonstrated the ability to control the acidity of their immediate environment, regardless of external influences – particularly corals which live in highly variable coastal environments.

It is interesting Heidi mentioned carbon capture sites as a possible risk to coastal ecosystems.

I’m not a fan of carbon capture. An abrupt volcanic CO2 release from Lake Nyos in 1986 killed people up to sixteen miles from the source of the release. Thankfully Lake Nyos was a sparsely inhabited region.

The amount of CO2 released in the Lake Nyos disaster was comparable to the amount of CO2 produced by a medium size coal plant in a month. There are thousands of medium size coal plants in the world, and some very big coal plants. Concentrating CO2 on a large scale is dangerous – the scale of CO2 concentration required for a serious global carbon capture effort would in my opinion ensure someone, somewhere would cut one corner too many. A Lake Nyos scale release near a major city could kill millions of people.