Spatial variability of phytoplankton primary production characteristics in the North Atlantic in summer 2013

Abstract

Spatial variability of phytoplankton primary production characteristics has been studied along the transects between Shetland Islands and Iceland (transect I) and along 59.5° N (transect II) from 30 June to 16 July 2013. It has been shown that surface chlorophyll a concentration (Chl0) varied more than two order of magnitude from 0.07 to 6.67 mg/m3 (transect I) and from 0.02 to 3.63 mg/m3 (transect II). Water column integrated primary production (IPP) 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 spatial variability of Chl0 and IPP was consistent with distribution of the main surface flows and thermohaline fronts. That conclusion was made on the basis of 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 nutrients concentration. That conclusion was confirmed by reliable positive correlation between optimum chlorophyll specific carbon fixation rate (Pbopt) and phosphate concentration (R = 0.58, p < 0.05, N = 76) and between Pbopt and dissolved silica (R = 0.51, p < 0.05, N = 76).