The investigation of size-fractionated chlorophyll a and primary productivity were carried out in three longitudinal sections (63°-69°12′S, 70°30′E, 73°E and 75 (30′E) at December 18 -26, 1998 and January 12 -18, 1999 in Prydz Bay and its north sea area, Antarctica. The results showed that surface chlorophyll a concentration were 0.16 -3.99 μg dm-3 The high values of chlorophyll a concentration (more than 3.5 μg dm-3) were in Prydz Bay and in the west Ladies Bank. Tlie average chlorophyll a concentration at sub-surface layer was higher than that at surface layer; its concentration at the deeper layers of 50 m decreased with increasing depth and that at 200 m depth was only 0.01 -0.95 μg dm -3. The results of size-fractionated chlorophyll a showed that the contribution of the netplanktion to total chlorophyll a was 56%, those of the nanoplankton and the picoplankton were 24% and 20% respectively in the surveyed area. The potential primary productivity at the euphotic zone in the surveyed area was 0.11-11.67 mgC m h-1 and average value was 2.00 ±2.80 mgC-3h-1 The in-shu productivity in the bay and the continental shelf was higher and that in the dcep-sca area was lower. The assimilation number of photosynthesis was 1.53±1.11 mgC/ ( mg Chi a·h ). The results of size-fractionated primary productivity show that the contribution of the netplanlction to total produo tivity was 58%, those of the nanoplankton and the picoplankton were 26% and 16% respectively. The ceil abundance of phytoplankton was 1.6×103-164.8×103 cell dm-3 in the surface water.
The distribution feature of size-fractionated chlorophyll a and primary productivity in Prydz Bay and its north sea area duringthe austral summer
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