Seawater carbonate chemistry and Microzooplankton and phytoplankton community composition of KOSMOS 2013 Gullmar Fjord mesocosm study

• Main Authors: Horn, Henriette G, Sander, Nils, Stuhr, Annegret, Algueró-Muñiz, Maria, Bach, Lennart Thomas, Löder, Martin G J, Boersma, Maarten, Riebesell, Ulf, Aberle, Nicole
• Format: Dataset
• Language: English
• Published: PANGAEA 2016
• Subjects: Abundance; Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Biological sample; BIOS; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Community composition and diversity; DATE/TIME; Day of experiment; Entire community; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gullmar_fjord_2013; Gullmar Fjord; Skagerrak; Sweden; Identification; Mesocosm or benthocosm; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Salinity; Silicate; Stereomicroscopy (Leica); Temperate; Temperature; water; Treatment; Type; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.956200; https://doi.org/10.1594/PANGAEA.956200

Ocean acidification is considered as a crucial stressor for marine communities. In this study, we tested the effects of the IPCC RPC6.0 end-of-century acidification scenario on a natural plankton community in the Gullmar Fjord, Sweden, during a long-term mesocosm experiment from a spring bloom to a mid-summer situation. The focus of this study was on microzooplankton and its interactions with phytoplankton and mesozooplankton. The microzooplankton community was dominated by ciliates, especially small Strombidium sp., with the exception of the last days when heterotrophic dinoflagellates increased in abundance. We did not observe any effects of high CO2 on the community composition and diversity of microzooplankton. While ciliate abundance, biomass and growth rate were not affected by elevated CO2, we observed a positive effect of elevated CO2 on dinoflagellate abundances. Additionally, growth rates of dinoflagellates were significantly higher in the high CO2 treatments. Given the higher Chlorophyll a content measured under high CO2, our results point at mainly indirect effects of CO2 on microzooplankton caused by changes in phytoplankton standing stocks, in this case most likely an increase in small-sized phytoplankton of <8 μm. Overall, the results from the present study covering the most important part of the growing season indicate that coastal microzooplankton communities are rather robust towards realistic acidification scenarios.