Marín-Samper, Laura; Arístegui, Javier; Faucher, Giulia; Kittu, Leila; Boersma, Maarten; Riebesell, Ulf (2026): KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: Microbial metabolic rates [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.996213 (DOI registration in progress)
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Published: 2026-07-27
Abstract:
Ocean alkalinity enhancement (OAE) is a marine carbon dioxide removal (mCDR) approach that can also mitigate ocean acidification. However, its biological impacts are expected to depend on the magnitude, timing, and dilution of alkalinity additions. To investigate these factors, a mesocosm experiment simulated hydrated lime additions using two six-level alkalinity gradients (up to ΔTA 1250 µmol kg⁻¹): one with immediate full-column mixing and another with mixing delayed by two days. These treatments simulated rapid (e.g. from a moving vessel in open ocean) and slow (e .g. point source or land-based applications in poorly mixed environments)dilution scenarios, representing different hydrodynamic conditions that may occur following real-world alkalinity additions. Gross production (GP), net community production (NCP) and community respiration (CR), determined from in vitro oxygen production and consumption, together with chlorophyll a, were monitored over a 35-day period. Spring bloom initiation was delayed non-linearly at low fCO₂, with reduced absolute and biomass-normalized production occurring in treatments exposed to fCO₂ below ~70 and 30 µatm respectively. These findings indicate that phytoplankton communities may be generally resilient to realistic OAE scenarios while helping to define ecologically relevant fCO₂ thresholds for safe OAE deployment.
Keyword(s):
Related to:
Marín-Samper, Laura; Arístegui, Javier; Faucher, Giulia; Kittu, Leila; Boersma, Maarten; Riebesell, Ulf (in press): Microbial metabolic rates under ocean alkalinity enhancement: A step towards a safe operating space. Communications Earth & Environment
Project(s):
Ocean Alk-Align (OceanAlkAlign)
Ocean-based Negative Emission Technologies (OceanNETs)
Funding:
Federal Ministry of Education and Research (BMBF), grant/award no. 03F0895A: DAM CDRmare - RETAKE, GEOMAR
Horizon 2020 of the European Commission (H2020), grant/award no. 731065: Network of Leading European AQUAtic MesoCOSM Facilities Connecting Mountains to Oceans from the Arctic to the Mediterranean
Horizon 2020 of the European Commission (H2020), grant/award no. 869357: OceanNETs: Ocean-based Negative Emission Technologies
Coverage:
Latitude: 54.183300 * Longitude: 7.900000
Date/Time Start: 2023-03-14T00:00:00 * Date/Time End: 2023-04-17T00:00:00
Event(s):
KOSMOS_2023_Mesocosm-M1 * Latitude: 54.183300 * Longitude: 7.900000 * Date/Time Start: 2023-03-14T00:00:00 * Date/Time End: 2023-04-21T00:00:00 * Location: Helgoland * Campaign: KOSMOS_2023 (KOSMOS Helgoland) * Method/Device: Mesocosm experiment (MESO)
KOSMOS_2023_Mesocosm-M2 * Latitude: 54.183300 * Longitude: 7.900000 * Date/Time Start: 2023-03-14T00:00:00 * Date/Time End: 2023-04-21T00:00:00 * Location: Helgoland * Campaign: KOSMOS_2023 (KOSMOS Helgoland) * Method/Device: Mesocosm experiment (MESO) * Comment: delayed treatment
KOSMOS_2023_Mesocosm-M3 * Latitude: 54.183300 * Longitude: 7.900000 * Date/Time Start: 2023-03-14T00:00:00 * Date/Time End: 2023-04-21T00:00:00 * Location: Helgoland * Campaign: KOSMOS_2023 (KOSMOS Helgoland) * Method/Device: Mesocosm experiment (MESO)
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Type of study | Study type | Marín-Samper, Laura | |||
| 2 | Event label | Event | Marín-Samper, Laura | |||
| 3 | Day of experiment | DOE | day | Marín-Samper, Laura | ||
| 4 | DATE/TIME | Date/Time | Marín-Samper, Laura | Geocode | ||
| 5 | Identification number | ID no | Marín-Samper, Laura | Mesocosm number | ||
| 6 | Treatment: dilution type | T:dilution | Marín-Samper, Laura | Dil_Treat | ||
| 7 | Treatment: alkalinity, total | T:AT | µmol/kg | Marín-Samper, Laura | Delta_TA | |
| 8 | Treatment | Treat | Marín-Samper, Laura | |||
| 9 | Sample code/label | Sample label | Marín-Samper, Laura | |||
| 10 | Respiration rate, oxygen, community | Comm resp O2 | µmol/l/day | Marín-Samper, Laura | CR: Community Respiration (amount of oxygen respired in the dark) | |
| 11 | Net community production of oxygen | NCP O2 | µmol/l/day | Marín-Samper, Laura | ||
| 12 | Gross community production of oxygen | GCP O2 | µmol/l/day | Marín-Samper, Laura | ||
| 13 | Balance | Balance | Marín-Samper, Laura | GPR: Metabolic Balance = GCP/CR | ||
| 14 | Depth, description | Depth desc | Marín-Samper, Laura |
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0) (License comes into effect after moratorium ends)
Status:
Curation Level: Enhanced curation (CurationLevelC)
Size:
2798 data points
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