Thermohaline characteristics and spatial distribution of chlorophyll along the standart transect “Kola Section” in April 2021

Abstract

In the Barents Sea, the major part of the annual primary pelagic production is formed during the spring phytoplankton bloom. A phytoplankton bloom is understood as an annually recurring increase in its total biomass. Chlorophyll a concentration reflects changes in phytoplankton biomass and can serve as an indicator of production characteristics. In April 2021, the thermohaline characteristics of the water column and the distribution of chlorophyll a concentrations along a standard transect “Kola Section” were studied. The Transect was located in the path of the warm waters of the Nordkapp current and the desalinated waters of the Murmansk coastal current. Coastal, Atlantic and Arctic waters were defined along the Transect. Chlorophyll a concentrations in coastal waters varied on average from 0.57 to 0.86 mg/m3 (maximum 1.11 mg/m3), in Atlantic waters from 0.11 to 0.34 mg/m3 (maximum 0.50 mg/m3). At the station located in the area of intensive interaction of two types of waters (in the area of salinity and temperature fronts) maximum concentrations of chlorophyll a (0.96–1.39 mg/m3) were noted. The location and extent of zones of increased (or decreased) chlorophyll a concentrations agreed with the alternation of water masses. The beginning of the early spring phytoplankton bloom was in the coastal zone of Central Murman.