An incubation experiment was conducted on board of the Canadian research icebreaker CCGS Amundsen between 6 and 15 August 2015. The water was collected near the nitracline at 38 m depth in Baffin Bay using 12-L Niskin-type bottles deployed on a CTD rosette system. A natural Arctic plankton community in a pre-bloom stage (initial high nutrient-low Chl a concentrations) was exposed over 9 days to reduced pH conditions under two contrasting light regimes. The two light regimes were designed to simulate the mean irradiance in an ice-free 5-m thick surface mixed layer (HL, marginal ice bloom conditions) and the mean irradiance at 5 m depth under a melting ponded ice pack (LL, under-ice bloom/ subsurface chlorophyll maximum conditions). The pH gradient comprised 6 levels covering the range of pH expected between the present and the year 2300. During the incubation, a phytoplankton bloom developed in every incubation bag and diatoms dominated the biomass (Chaetoceros spp.). Temporal variations of pH, dissolved inorganic carbon, total alkalinity, chlorophyll a, macronutrients, DMS(P), flow cytometry (nano- and pico-phytoplankton, bacteria, virus), taxonomy, salinity and incubator's temperature are available.
