Seawater carbonate chemistry and phytoplankton biomass during the BIOACID II indoor mesocosm study in the Kiel Fjord (Baltic Sea)

• Main Authors: Paul, Allanah J, Sommer, Ulrich, Paul, Carolin, Riebesell, Ulf
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2018
• Subjects: Baltic Sea; Biomass/Abundance/Elemental composition; Coast and continental shelf; Community composition and diversity; Entire community; Laboratory experiment; Mesocosm or benthocosm; Pelagos; Temperate; Temperature; Type; DATE/TIME; Day of experiment; Mesocosm label; Sample code/label; Phase; Treatment temperature; Nodularia spp., biomass; Dolichospermum spp., biomass; Nostoc sp., biomass as carbon; Phytoplankton, biomass; Ratio; δ15N; Phosphate, organic, dissolved; Phosphate; Silicate; Alkalinity, total; Carbon, inorganic, dissolved; Partial pressure of carbon dioxide water at sea surface temperature wet air; pH; Salinity; Temperature, water; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Aragonite saturation state; Calcite saturation state; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.901801; https://doi.pangaea.de/10.1594/PANGAEA.901801

Nitrogen fixation is a key source of nitrogen in the Baltic Sea which counteracts nitrogen loss processes in the deep anoxic basins. Laboratory and field studies have indicated that single-strain nitrogen-fixing (diazotrophic) cyanobacteria from the Baltic Sea are sensitive to ocean acidification and warming, 2 drivers of marked future change in the marine environment. Here, we enclosed a natural plankton community in 12 indoor mesocosms (volume 1400 l) and manipulated partial pressure of carbon dioxide ( pCO2) in seawater to yield 6 CO2 treatments with 2 different temperature treatments (16.6°C and 22.4°C, pCO2 range = 360-2030 µatm). We followed the filamentous, heterocystous diazotrophic cyanobacteria community (Nostocales, primarily Nodularia spumigena) over 4 wk. Our results indicate that heterocystous diazotrophic cyanobacteria may become less competitive in natural plankton communities under ocean acidification. Elevated CO2 had a negative impact on Nodularia sp. biomass, which was exacerbated by warming. Our results imply that Nodularia sp. may contribute less to new nitrogen inputs in the Baltic Sea in the future. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2016) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation is 2016-12-16.