KOSMOS Finland 2012 mesocosm study: Phytoplankton biomass and pigment concentration, Nitrogen cycle parameters

• Main Authors: Paul, Allanah Joy, Stuhr, Annegret, Boxhammer, Tim
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: Aphanizomenon flos-aquae; biomass as carbon; Aphanizophyll; BIOACID; Biological Impacts of Ocean Acidification; Chaetoceros sp.; DATE/TIME; Day of experiment; KOSMOS_2012_Tvaerminne; MESO; Mesocosm experiment; Mesocosm label; Nitrogen fixation rate; Phase; Skeletonema marinoi; δ15N; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.889312; https://doi.org/10.1594/PANGAEA.889312

Nitrogen fixation by filamentous cyanobacteria supplies significant amounts of new nitrogen (N) to the Baltic Sea. This balances N loss processes such as denitrification and anammox, and forms an important N source supporting primary and secondary production in N-limited post-spring bloom plankton communities. Laboratory studies suggest that filamentous diazotrophic cyanobacteria growth and N2-fixation rates are sensitive to ocean acidification, with potential implications for new N supply to the Baltic Sea. In this study, our aim was to assess the effect of ocean acidification on diazotroph growth and activity as well as the contribution of diazotrophically fixed N to N supply in a natural plankton assemblage. We enclosed a natural plankton community in a summer season in the Baltic Sea near the entrance to the Gulf of Finland in six large-scale mesocosms (volume ∼ 55m3) and manipulated fCO2 over a range relevant for projected ocean acidification by the end of this century (average treatment fCO2: 365–1231µatm).