[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-565279-105":3,"detail-sidebar-cat-1-en-105":80,"doc-detail-565279-en":126},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":73,"head_meta":75,"extra_data":77,"updated_unix":79},105,"en","biogeosciences-22-18651886-2025","Biogeosciences 22 - 1865–1886 - 2025","","A natural plankton community from oligotrophic subtropical waters of the Atlantic near Gran Canaria was exposed to varying ocean alkalinity enhancement (OAE) levels to evaluate physiological impacts for ocean carbon dioxide removal (CDR). Nine 8.3 m3 mesocosms created a total alkalinity gradient from 2400 to 4800 µmol L−1 and were run for 33 days. Phase I showed reduced photosynthetic efficiency with declines in several plankton groups without significant ROS changes; Phase II showed blooms, chlorophyll and pigment increases, and a ~20% shift in the metaproteome, while medium OAE produced more upregulation and less downregulation, overall indicating no cellular stress and no impaired fitness.",{"@graph":14,"@context":72},[15,34,55],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/template/","Template",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/template/general/","General",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/template/biogeosciences-22-18651886-2025/565279/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/biogeosciences-22-18651886-2025/565279.png","ImageObject",442,249,{"name":42,"@type":43},"supergirl","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-25","2026-10-13",true,{"@type":52,"interactionType":53,"userInteractionCount":30},"InteractionCounter",{"@type":54},"ViewAction",{"@type":56,"mainEntity":57},"FAQPage",[58,64,68],{"name":59,"@type":60,"acceptedAnswer":61},"What experimental setup was used to test ocean alkalinity enhancement (OAE)?","Question",{"text":62,"@type":63},"Nine mesocosms (8.3 m3 each) with sediment traps were used to create a gradient in total alkalinity by adding carbonates (NaHCO3 and Na2CO3). The experiment lasted 33 days.","Answer",{"name":65,"@type":60,"acceptedAnswer":66},"What changed during phase I of the OAE exposure?",{"text":67,"@type":63},"From days 5–20, photosynthetic efficiency (Fv/Fm) declined and abundances of multiple plankton groups decreased, while ROS levels showed no significant changes.",{"name":69,"@type":60,"acceptedAnswer":70},"Did OAE cause cellular stress to the studied phytoplankton community?",{"text":71,"@type":63},"Overall, the study concludes that OAE did not cause cellular stress and that physiological fitness was not impaired; nutrient limitation was suggested for observed cell-number drawdowns at times.","https://schema.org",{"og:url":32,"og:type":74,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":76,"canonical":32},"index,follow",{"doc_id":78,"site_id":7},565279,1792567971,{"code":4,"msg":81,"data":82},"success",[83,88,93,98,103,108,113,118,123],{"id":84,"doc_module":22,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},11,"Presentations",90,"presentations",{"id":89,"doc_module":22,"doc_module_name":25,"category_name":90,"show_sort_weight":91,"slug":92},12,"Resumes",80,"resumes",{"id":94,"doc_module":22,"doc_module_name":25,"category_name":95,"show_sort_weight":96,"slug":97},14,"Invoices",70,"invoices",{"id":99,"doc_module":22,"doc_module_name":25,"category_name":100,"show_sort_weight":101,"slug":102},15,"Posters",60,"posters",{"id":104,"doc_module":22,"doc_module_name":25,"category_name":105,"show_sort_weight":106,"slug":107},16,"Social Media",50,"social-media",{"id":109,"doc_module":22,"doc_module_name":25,"category_name":110,"show_sort_weight":111,"slug":112},17,"Forms",40,"forms",{"id":114,"doc_module":22,"doc_module_name":25,"category_name":115,"show_sort_weight":116,"slug":117},18,"Letters",30,"letters",{"id":119,"doc_module":22,"doc_module_name":25,"category_name":120,"show_sort_weight":121,"slug":122},21,"Paper Templates",5,"papers-templates",{"id":124,"doc_module":22,"doc_module_name":25,"category_name":29,"show_sort_weight":4,"slug":125},158,"general-158",{"code":4,"msg":81,"data":127},{"doc_id":78,"user_id":128,"nickname":42,"user_avatar":129,"doc_module":22,"category_id":124,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":30,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":135,"language":136,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":137,"faqs":138,"seo_title":139,"seo_description":12,"update_tm":140,"read_time":141},962088121634,"https://ap-avatar.wpscdn.com/davatar_9964176cb1d06d4a9deccf72a44ae3dc","Biogeosciences, 22, 1865–1886, 2025  \n[https://doi.org/10.5194/bg-22-1865-2025](https://doi.org/10.5194/bg-22-1865-2025)[ ](https://doi.org/10.5194/bg-22-1865-2025)© Author(s) 2025 . This work is distributed under the Creative Commons Attribution 4 .0 License.  \nOcean alkalinity enhancement (OAE) does not cause cellular stress in a phytoplankton community of the subtropical Atlantic Ocean  \nLibrada Ramírez 1 , Leonardo J. Pozzo-Pirotta 1 , Aja Trebec2 , Víctor Manzanares-Vázquez 1 , José L. Díez 1 , Javier Arístegui2 , Ulf Riebesell3 , Stephen D. Archer4 , and María Segovia 1  \n1Department of Ecology, Faculty of Sciences, University of Malaga, Malaga, Spain  \n2Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Las Palmas, Spain  \n3 GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany  \n4Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA Correspondence: Librada Ramírez ([librada@uma.es](librada@uma.es))  \nReceived: 21 March 2024 – Discussion started: 2 April 2024  \nRevised: 5 January 2025 – Accepted: 10 January 2025 – Published: 16 April 2025  \nAbstract. A natural plankton community from oligotrophic subtropical waters of the Atlantic near Gran Canaria, Spain, was subjected to varying degrees of ocean alkalinity enhancement (OAE) to assess the potential physiological effects in the context of the application of ocean carbon dioxide removal (CDR) techniques. We employed nine mesocosms with sediment traps attached to the bottom, each enclosing a volume of 8 .3 m3 , to create a gradient in total alkalinity (TA) . OAE was based on the addition of carbonates (NaHCO 3 and Na2 CO3) . The lowest point on this gradient was 2400 µmolL􀀀1, which corresponded to the natural alkalinity of the environment, and the highest point was 4800 µmolL􀀀1 . Over the course of the 33 d experiment, the plankton community exhibited two distinct phases. In phase I (days 5–20), a notable decline in the photosynthetic efficiency ( Fv =Fm) was observed. This change was accompanied by substantial reductions in the abundances of picoeukaryotes, small-size nanoeukaryotes (nanoeukaryotes- 1), and microplankton. The cell viability of picoeukaryotes, as indicated by fluorescein diacetate hydrolysis by cellular esterases (FDA green fluorescence), slightly increased by the end of phase I, whilst the viability of nanoeukaryotes- 1 and Synechococcus spp. did not change. Reactive oxygen species levels (ROS green fluorescence) showed no significant changes for any of the functional groups. In contrast, in phase II (days 21–33), a pronounced community response was observed. Increases in Fv =Fm in the intermediate OAE treatments of 1900 to 11800 µmolL􀀀1 and in chlorophyll a  \n(Chl a), chlorophyll c2 (Chl c2), fucoxanthin, and divinyl Chl a were attributed to the emergence of blooms of largesize nanoeukaryotes (nanoeukaryotes-2) from the genera Chrysochromulina, as well as picoeukaryotes. Synechococcus spp. also flourished towards the end of this phase. In parallel, we observed a significant change of 20 % in the overall metaproteome of the phytoplankton community. This is considered a significant alteration in protein expression, having a substantial impact on cellular functions and the physiology of the organisms. Medium levels of 1TA showed more upregulated and less-downregulated proteins than higher 1TA treatments. Under these conditions, cell viability significantly increased in pico-and nanoeukaryotes-1 at intermediate alkalinity levels, while in Synechococcus spp., nanoeukaryotes-2 and microplankton remained stable. ROS levels did not significantly change in any functional group. The pigment ratios DD CDT : FUCO and DD CDT : Chl a increased in medium 1TA treatments, supporting the idea of nutrient deficiency alleviation and the absence of physiological stress. When all data are taken together, this study shows that OAE did not cause cellular stress in the phytoplankton community studied, and physiologica","cbCaisQERgOxsvwf","https://ap.wps.com/l/cbCaisQERgOxsvwf","pdf",2319732,22,"English","# Abstract\n## Introduction","[{\"question\":\"What experimental setup was used to test ocean alkalinity enhancement (OAE)?\",\"answer\":\"Nine mesocosms (8.3 m3 each) with sediment traps were used to create a gradient in total alkalinity by adding carbonates (NaHCO3 and Na2CO3). The experiment lasted 33 days.\"},{\"question\":\"What changed during phase I of the OAE exposure?\",\"answer\":\"From days 5–20, photosynthetic efficiency (Fv/Fm) declined and abundances of multiple plankton groups decreased, while ROS levels showed no significant changes.\"},{\"question\":\"Did OAE cause cellular stress to the studied phytoplankton community?\",\"answer\":\"Overall, the study concludes that OAE did not cause cellular stress and that physiological fitness was not impaired; nutrient limitation was suggested for observed cell-number drawdowns at times.\"}]","Biogeosciences 22 - 1865–1886 - 2025 | PDF",1791850480,8]