Seasonal ecophysiology of Fucus vesiculosus (Phaeophyceae) in the Northern Baltic Sea

This dataset contains ecophysiological measurements of brown algae <em>Fucus vesiculosus</em> and environmental variables, measured in different seasons in 2017 in the Northern Baltic Sea, SW Finland. More specifically, the measured parameters include in situ chlorophyll <em>a</em> fluorescence: F_v/F_m, maximum relative electron transport rate, and quantum yield of photochemistry. Carbon and nitrogen content, carbon:nitrogen ratio and chlorophyll <em>a</em> and <em>c</em> content were determined in the laboratory. Environmental parameters monitored include in situ irradiance, temperature, salinity, alkalinity, DIC, pCO₂, HCO₃^-, CO₃^2-, CO₂, seawater nitrogen (NO₂^- and NO₃^-) and phosphorus (PO₄^3-). Measurements were conducted in February, May, July, September and November in two sites, with additional three sites sampled in July. Irradiance was measured with 1 meter depth intervals from the surface. Irradiance values in the data are irradiances at <em>F. vesiculosus</em> sampling depths in each site, estimated with linear regression from the irradiance and depth data. F_v/F_m values for sites Spikarna, Ekö and Björnholmen in July were imputed from other variables using R package "Amelia".