Abstract:

Nutrient data collected in Prydz Bay during the CHINARE 25/27/29 cruises were analyzed to study the
distribution pattern of nutrient concentrations. The consumption, absorption ratio, and structure of nutrients
(NNU, NPU, and NSiU) in summer were evaluated based on the existence of the Tmin layer. The results
showed that the spatial distributions of nutrient concentrations in the surface waters of Prydz Bay had obvious
regional characteristics. The highest, intermediate, and lowest concentrations of nutrients were observed
in the open sea, continental shelf, and marginal ice shelf areas, respectively. Consumption of nutrients in
inner areas of Prydz Bay was higher than outer areas partly because of the influence of the phytoplankton
bloom in austral summer; a period in which nutrients are absorbed by phytoplankton for photosynthesis. The
NSiU/NNU ratios showed distribution patterns similar to nutrient concentrations but opposite to Chla concentration.
It is speculated that this difference is mainly due to the higher supply of iron in the continental
shelf region and inner Prydz Bay area comparted with the open sea. Investigation of the structure and
changes of nutrient concentrations in Prydz Bay can help us better understand the biogenic element cycle
processes in the Southern Ocean and provide a basis for predicting the evolution of phytoplankton structure
in the Southern Ocean.

Key words: nutrients, spatial distributions, seasonal depletion, remove ratios, Prydz Bay