Spatial Variability of Phytoplankton Primary Production Characteristics in the North Atlantic in Summer 2013

Abstract

The spatial variability of phytoplankton primary production characteristics has been studied along transects between the Shetland Islands and Iceland (transect I) and along 59.5° N (transect II) from June 30 to July 16, 2013. It has been shown that the surface chlorophyll a concentration (Chl₀) varied within more than two orders of magnitude from 0.07 to 6.67 mg/m³ along transect I and from 0.02 to 3.63 mg/m³ along transect II. The water column primary production (PP_int) changed by a factor of 3.8 from 273 to 1040 and by a factor of 5.6 from 68 to 379 mgC/m² per day along transects I and II, respectively. It has been established that the spatial variability of Chl₀ and PPint was consistent with the distribution of the main surface flows and thermohaline fronts. This conclusion was made based on a reliable positive correlation between Chl₀ and the zonal potential temperature gradient (R = 0.43, p < 0.01, N = 65). Phytoplankton assimilation activity along transect II depends on the nutrient concentration. This is confirmed by the reliable positive correlation of the assimilation number with the phosphate concentrations (R = 0.58, p < 0.05, N = 76) and dissolved silicon (R = 0.51, p < 0.05, N = 76).