18S-metabarcoding data of an indoor mesocosm experiment testing the effect of temperature on a plankton community from Helgoland Roads, March 2022
To investigate the effect of temperature on a North Sea spring bloom community, we performed an incubation experiment in the mesocosm facility of the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven. The plankton community was sampled from the long-term ecological research station Helgoland Roads (https://deims.org/1e96ef9b-0915-4661-849f-b3a72f5aa9b1) on the 6th of March, 2022. Collection of the surface community was conducted from the RV Heincke with a pipe covered with a 200 µm net that was attached to a diaphragm pump. The month-long incubation was started on the 7th of March in twelve indoor mesocosms, the Planktotrons (Gall et al. (2017)). We chose three temperatures along the ascending part of the thermal performance curve (TPC) of the in situ community: the minimum temperature for positive growth (6°C, also the field temperature), the middle between the minimum and the optimum temperature (12 °C), and the optimum temperature for growth (18 °C). Ramping up the temperatures was conducted by 1 °C per day until the treatment temperatures were reached, resulting in a ramp phase (first twelve days) and an constant temperature phase. This dataset comprises all data collected within the experiment. Temperature, oxygen, pH, salinity, and in vivo fluorescence were measured daily at 10 am. Samples for dissolved nutrients (nitrate, nitrite, phosphate, silicate), chlorophyll a, DNA, particulate nutrients (biogenic silica, particulate organic carbon/nitrogen/phosphorus), as well as flow cytometric counts of bacteria (stained) and the unstained community were taken every third day at the same time. The mesocosm water was generally filtered over a 200 µm mesh before sampling to exlucde mesozooplankton. However, due to the appearance of large Phaeocystis colonies, additional samples without pre-filtration were taken for particulate organic carbon, nitrogen, phosphorus, and chlorophyll a starting on incubation day 15. PAR, total nitrogen and phosphorus as well as total alkalinity were measured at the start, in the middle, and at the end of the incubation. Samples for Mesozooplankton enumeration and identification were taken at the end. To choose the treatment temperatures, a TPC assay was started one day after filling the mesocosms (March 8th) by randomly spreading pooled sample water in 50 mL culture flasks across ten temperatures (3 °C to 30 °C in 3 °C steps) in triplicates. Their fluorescence (395/680 Excitation/Emission) was measured daily using a SYNERGY H1 microplate reader (BioTek, Winooski, Vermont, USA). All scripts can be found on github (https://github.com/AntoniaAhme/TopTrons22MesocosmIncubation).