A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum
Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO 2 . However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and p CO 2 . Here we describe a system in which the target p CO 2 i...
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crpeerj:10.7717/peerj.2503 2024-06-02T08:12:33+00:00 A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum Sordo, Laura Santos, Rui Reis, Joao Shulika, Alona Silva, Joao Fundação para a Ciência e a Tecnologia (FCT) FCT doctoral grant 2016 http://dx.doi.org/10.7717/peerj.2503 https://peerj.com/articles/2503.pdf https://peerj.com/articles/2503.xml https://peerj.com/articles/2503.html en eng PeerJ http://creativecommons.org/licenses/by/4.0/ PeerJ volume 4, page e2503 ISSN 2167-8359 journal-article 2016 crpeerj https://doi.org/10.7717/peerj.2503 2024-05-07T14:14:07Z Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO 2 . However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and p CO 2 . Here we describe a system in which the target p CO 2 is controlled via direct analysis of p CO 2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA) that measures p CO 2 and conveys this value to a Proportional-Integral-Derivative (PID) controller. The controller commands a solenoid valve that opens and closes the CO 2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of p CO 2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum . We found that after 11 months of high CO 2 exposure, photosynthesis increased with CO 2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO 2 , such as temperature, irradiance and nutrients. Article in Journal/Newspaper Ocean acidification PeerJ Publishing PeerJ 4 e2503 |
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English |
description |
Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO 2 . However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and p CO 2 . Here we describe a system in which the target p CO 2 is controlled via direct analysis of p CO 2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA) that measures p CO 2 and conveys this value to a Proportional-Integral-Derivative (PID) controller. The controller commands a solenoid valve that opens and closes the CO 2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of p CO 2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum . We found that after 11 months of high CO 2 exposure, photosynthesis increased with CO 2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO 2 , such as temperature, irradiance and nutrients. |
author2 |
Fundação para a Ciência e a Tecnologia (FCT) FCT doctoral grant |
format |
Article in Journal/Newspaper |
author |
Sordo, Laura Santos, Rui Reis, Joao Shulika, Alona Silva, Joao |
spellingShingle |
Sordo, Laura Santos, Rui Reis, Joao Shulika, Alona Silva, Joao A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
author_facet |
Sordo, Laura Santos, Rui Reis, Joao Shulika, Alona Silva, Joao |
author_sort |
Sordo, Laura |
title |
A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
title_short |
A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
title_full |
A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
title_fullStr |
A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
title_full_unstemmed |
A direct CO 2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum |
title_sort |
direct co 2 control system for ocean acidification experiments: testing effects on the coralline red algae phymatolithon lusitanicum |
publisher |
PeerJ |
publishDate |
2016 |
url |
http://dx.doi.org/10.7717/peerj.2503 https://peerj.com/articles/2503.pdf https://peerj.com/articles/2503.xml https://peerj.com/articles/2503.html |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
PeerJ volume 4, page e2503 ISSN 2167-8359 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.7717/peerj.2503 |
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PeerJ |
container_volume |
4 |
container_start_page |
e2503 |
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1800759013529354240 |