ATP, chlorophyll a, and size structure of phytoplankton in seawater at stations in the Atlantic sector of the Southern Ocean

ATP values varied from 11 to 92 ng/l, and chlorophyll "a" concentrations varied from 0.04 to 0.27 µg/l in the Indian Ocean, with prevailing nanoplankton and picoplankton fractions. Both ATP and chlorophyll "a" concentrations increased 2 times to the south of 40°S; in the Weddell Sea they exceeded 400 ng/l and 0.6 µg/l, respectively.

Cells of nanophytoplankton and microphytoplankton (mainly diatoms) prevailed in size spectra. Spatial variabilities of the parameters were within one order of magnitude; their values decreased 3-4 times during 1 month. Size structure changed due to increased portion of nanoplankton and picolankton.