Petric Svetlana spetric@geomar.de GEOMAR - Helmholtz Centre for Ocean Research Kiel GEOMAR http://www.geomar.de https://ror.org/02h2x0161 Faucher Giulia gfaucher@geomar.de 0000-0001-8930-477X GEOMAR - Helmholtz Centre for Ocean Research Kiel GEOMAR http://www.geomar.de https://ror.org/02h2x0161 Riebesell Ulf uriebesell@geomar.de https://www.geomar.de/uriebesell/ 0000-0002-9442-452X GEOMAR - Helmholtz Centre for Ocean Research Kiel GEOMAR http://www.geomar.de https://ror.org/02h2x0161 2026 KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: phytoplankton and microzooplankton abundance and biomass data dataset https://doi.pangaea.de/10.1594/PANGAEA.996209 2026-07-31T10:46:39 This dataset contains species-resolved phytoplankton and microzooplankton abundance and biomass data from the KOSMOS 2023 Helgoland mesocosm experiment conducted in the coastal waters off Helgoland Island in the North Sea, Germany. The experiment investigated the effects of Ocean Alkalinity Enhancement (OAE) on plankton communities during the development of a natural spring bloom. Six mesocosms (~6 m³) were subjected to an immediate dilution OAE scenario, establishing an alkalinity enhancement gradient ranging from ΔTA 0 to 1250 µmol kg⁻¹ in increments of 250 µmol kg⁻¹ through calcium-based alkalinity addition. The dataset includes taxonomically resolved phytoplankton and microzooplankton abundance (cells mL⁻¹), carbon biomass (µg C L⁻¹), functional group classifications, and World Register of Marine Species (WoRMS) taxonomic identifiers. Associated carbonate chemistry measurements, including total alkalinity (TA), dissolved inorganic carbon (DIC), pH, fugacity of carbon dioxide (fCO₂), salinity, temperature, and calculated ΔTA values are provided for each sampling event. 7.8999999999999995 7.8999999999999995 54.18330000000001 54.18330000000001 7.8999999999999995 54.18330000000001 2023-03-16T00:00:00 2023-04-21T00:00:00 RETAKE DAM CDRmare - RETAKE: CO2 removal by alkalinity enhancement: potential, benefits and risks https://retake.cdrmare.de/en/ GEOMAR - Helmholtz Centre for Ocean Research Kiel GEOMAR http://www.geomar.de https://ror.org/02h2x0161 OceanAlkAlign Ocean Alk-Align https://alkalign.ocean.dal.ca/ Dalhousie University https://ror.org/01e6qks80 CDRmare Research Mission of the German Marine Research Alliance (DAM): Marine carbon sinks in decarbonisation pathways https://cdrmare.de/en/ GEOMAR - Helmholtz Centre for Ocean Research Kiel GEOMAR http://www.geomar.de https://ror.org/02h2x0161 Federal Ministry of Education and Research BMBF https://www.bmftr.bund.de https://doi.org/10.13039/501100002347 03F0895A DAM CDRmare - RETAKE, GEOMAR https://foerderportal.bund.de/foekat/jsp/SucheAction.do?actionMode=view&fkz=03F0895A KOSMOS_2023_Mesocosm-M1 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg KOSMOS_2023_Mesocosm-M3 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg KOSMOS_2023_Mesocosm-M5 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg KOSMOS_2023_Mesocosm-M7 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg KOSMOS_2023_Mesocosm-M9 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg KOSMOS_2023_Mesocosm-M11 54.1833 7.9 Helgoland 2023-03-14T00:00:00 2023-04-21T00:00:00 KOSMOS_2023 KOSMOS_2023 KOSMOS Helgoland KOSMOS Helgoland 2023-03-13T00:00:00 2023-03-13 2023-04-21T00:00:00 2023-04-21 Riebesell, Ulf Riebesell, Ulf Mesocosm experiment MESO http://invabio.wdc-mare.org/mesocubi.jpg 58140 CC-BY-4.0 Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ Type of study Study type type Petric Svetlana spetric@geomar.de Study type Event label Event Petric Svetlana spetric@geomar.de Event Sample code/label Sample label Petric Svetlana spetric@geomar.de Sample label DATE/TIME Date/Time http://en.wikipedia.org/wiki/ISO_8601 Time T http://dbpedia.org/resource/Time Petric Svetlana spetric@geomar.de Date/Time Day of experiment DOE day day Time T http://dbpedia.org/resource/Time Petric Svetlana spetric@geomar.de DOE [day] Treatment: dilution type T:dilution treatment Petric Svetlana spetric@geomar.de Dilution type T:dilution Treatment Treat treatment Petric Svetlana spetric@geomar.de Targeted alkalinity level and mesocosm Treat Treatment: alkalinity, total T:AT µmol/kg treatment total https://www.oxforddictionaries.com/definition/american_english/total Molar Concentration Petric Svetlana spetric@geomar.de Treatment level T:AT [µmol/kg] Alkalinity, total AT µmol/kg total https://www.oxforddictionaries.com/definition/american_english/total Molar Concentration Titration device, Metrohm, 862 Compact Titrosampler [with built-in PT1000 temperature sensor] Petric Svetlana spetric@geomar.de AT [µmol/kg] Carbon, inorganic, dissolved DIC µmol/kg carbon C https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:27594 dissolved http://purl.obolibrary.org/obo/PATO_0001986 Molar Concentration Automated Infra Red Inorganic Carbon Analyzer (AIRICA), MARIANDA; coupled with Differential infrared gas analyzer, LI-COR Biosciences, LI-7000 Petric Svetlana spetric@geomar.de DIC [µmol/kg] pH pH Calculated using the CO2sys_v3.0 software (Pierrot et al. 2021) https://github.com/dpierrot/co2sys_xl Petric Svetlana spetric@geomar.de pH Fugacity of carbon dioxide in seawater fCO2 ppmv fugacity https://en.wikipedia.org/wiki/Fugacity carbon dioxide http://purl.obolibrary.org/obo/CHEBI_16526 seawater Calculated using the CO2sys_v3.0 software (Pierrot et al. 2021) https://github.com/dpierrot/co2sys_xl Petric Svetlana spetric@geomar.de fCO2 [ppmv] Salinity Sal salinity http://purl.obolibrary.org/obo/PATO_0085001 CTD 60M multiparameter probe (Sea & Sun Technology GmbH, Germany) CTD http://vocab.nerc.ac.uk/collection/L05/current/130/ CTD & XBT Petric Svetlana spetric@geomar.de Sal Temperature, water Temp °C Temperature Θ http://dbpedia.org/resource/Temperature water http://purl.obolibrary.org/obo/CHEBI_15377 CTD 60M multiparameter probe (Sea & Sun Technology GmbH, Germany) CTD http://vocab.nerc.ac.uk/collection/L05/current/130/ CTD & XBT Petric Svetlana spetric@geomar.de Temp [°C] Species Species https://en.wikipedia.org/wiki/Species species Reference in WoRMS WoRMS https://www.marinespecies.org Petric Svetlana spetric@geomar.de Species Species, unique identification Species UID species Reference in WoRMS WoRMS https://www.marinespecies.org Petric Svetlana spetric@geomar.de Species UID Functional group Functional gr functional http://purl.obolibrary.org/obo/PATO_0001510 Calculated Petric Svetlana spetric@geomar.de Functional gr Cell Cell #/ml cell Microscopy Petric Svetlana spetric@geomar.de Utermöhl microscopy Cell [#/ml] Biomass as carbon per volume Biom C µg/l biomass carbon C https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:27594 Volume http://dbpedia.org/resource/Volume Density http://dbpedia.org/resource/Density Microscopy Petric Svetlana spetric@geomar.de Utermöhl microscopy Biom C [µg/l] CurationLevelC Enhanced curation https://wiki.pangaea.de/wiki/Curation_levels Abundance Biomass ciliates community composition Community composition and diversity diatoms Dinoflagellates enhancement Field experiment Helgoland Marine Carbon Dioxide Removal (mCDR) mesocosm mesocosm experiment mesocosm study microscopy microzooplankton North Sea ocean alkalinity enhancement Ocean Alkalinity Enhancement (OAE) Phytoplankton Phytoplankton biomass Phytoplankton bloom spring bloom geomar author103704 author10403 author118571 award2769 campaign3395033 campaign52642 curlevel30 event3299309 event3299311 event3299313 event3299315 event3299317 event3299319 funder20473 geocode1599 geocode1600 geocode1601 inst20147 inst21772 license21 method11277 method16006 method18787 method18789 method50 method6609 method9144 method9759 param159890 param185520 param26116 param29999 param45618 param510679 param527839 param551091 param7053 param716 param717 param764 param78394 param790 param80114 param87073 param96278 pi118571 project4757 project4784 project5044 term1073490 term1073493 term1074475 term2299371 term242 term2606205 term2687852 term2687856 term2698012 term361 term38253 term38477 term38842 term38896 term40551 term40594 term41013 term41062 term43792 term43972 term43975 term43984 term44030 term48046 term48166 term48791 term48982 term49384 term49506 term49771 term50119 term50714 term51866 term52330 term53688 term597 term60979 term67626 term68280 term71465 term72711 term73463 term738 term77192 term77345 term77452 term77453