Warming and acidification effects on planktonic heterotrophic Pico- and Nanoflagellates in a mesocosm experiment

• Main Authors: Moustaka-Gouni, Maria, Kormas, Konstantinos A, Scotti, Marco, Vardaka, S, Sommer, Ulrich
• Format: Dataset
• Language: English
• Published: PANGAEA 2016
• Subjects: Abundance per volume; Alkalinity; total; Aragonite saturation state; Baltic Sea; Bay of Kiel; Bicarbonate ion; Biomass; Biomass/Abundance/Elemental composition; 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; Day of experiment; Entire community; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Kiel_Bight; Laboratory experiment; Mesocosm or benthocosm; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Ratio; Salinity; Sample code/label; Size fraction; Temperate; Temperature; water; Treatment; Type; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.873191; https://doi.org/10.1594/PANGAEA.873191

We studied the response of the heterotrophic flagellate (HF) community to the combined impact of warming and ocean acidification in a mesocosm experiment with a plankton community from the western Baltic Sea. We performed a quantitative analysis of the response at the level of total biomass and size classes and a semi-quantitative one at the level of individual taxa. Total biomass of HF was significantly lower under higher temperatures while there was no significant effect of CO2. The mean biomass of the picoflagellates did not respond to temperature while the three nanoflagellate size classes (class limits 3, 5, 8, 15 ?m) responded negatively to warming while not responding to CO2. The taxon-level results indicate that heterotrophic flagellates do not form a homogenous trophic guild, as often assumed in pelagic food web studies. Instead, the heterotrophic flagellates formed a ?food web within the food web?. There was a pronounced succession of flagellates leading from a dominance of bacterivores and colloidal matter feeders before the phytoplankton bloom to omnivorous feeders preying upon phytoplankton and heterotrophic flagellates during and after the bloom. This complex intraguild predation patterns probably dampened the response to experimental treatments.