Phytoplankton and Environmental Factors in the Southeastern Barents Sea during August 2003

Abstract

In order to grasp the structure and dynamics of phytoplankton communities, chlorophyll-a (Chl-a) and cell abundance were measured at 20 stations during the period from August 9 to August 21, 2003 in the southeastern Barents Sea on surface and subsurface chlorophyll maximum depth (SCM). Surface temperatures were varied from minimum 0.7oC(st. 18) to maximum 10.4oC(st. 1). Salinities were varied from minimum 29.9 psu(st. 18) to maximum 35.8 psu(st. 2). The maximum nutrient(phosphate, nitrate, silicate) concentrations were 0.12 M, 0.11 M, 7.53 M and minimum concentrations were 0.01 M, 0.03 M, 1.43 M, respectively. On SCM physical environmental factor were almost similar. Chl-a concentrations ranged from 0.23 to 2.13g chl-a l1 at SCM. Nano- and pico phytoplankton were the important contributors for increase of the Chl-a. It was about seven times difference between highest concentration to lowest. Phytoplankton communities were composed of diatoms, dinoflagellates, cryptophyceae, silicoflagellate, and prymnesiophyceae showing 37 taxa at surface and 38 taxa at SCM. Picophytoplankton was the most dominant in all stations and all layers, but the second groups were 2 and/or 3 taxa. Phytoplankton abundance ranged from minimum 4.3105 cells l1(st. 20) to maximum 2.4×106 cells l1(st. 17) at surface water. As a result, phytoplankton might be controlled by physical factors such as North Atlantic ocean currents and northern melt water among environmental factors in Barents Sea. In addition the dominant species were nano- and pico phytoplankton such as Phaeocystis, Cryptomonas and Dinobryon in the study area.