The project AWI-funded AMUST project aims at understanding at current and future controls of Arctic spring blooms and concurrrent effetcs on biogeochemistry,by combining experimental work with long-term monitoring in April and May each year to study the Kongsfjorden spring bloom. This dataset was also used in the FAABulous project to compare spring bloom phenology in open-water and ice-covered fjords. Environmental as well as biological (stoichiometry and photosynthesis) data from the years 2014, and 2016-2018 for the mid-fjord station KB3 were samples. Furthermore, daily average temperature and salinity from a nearby mooring (see Hop et al. 2019 for details) are provided for the study period.