Nitrogen (N) assimilation and regeneration in hypoxic water column of Jinhae Bay, South Korea

Abstract:

Nitrogen generally controls the phytoplankton productivity in marine environment and detailed information regarding N cycling is necessary to understand extreme ecological processes such as hypoxic condition. Generally, primary production was measured using oxygen evolution or stable ¹³C isotope tracer experiment and nitrogen assimilation rate were estimated assuming certain carbon to nitrogen ratio. The regeneration of N is also estimated from the respiration rates although direct measurement method was applied in some experiments. We measured both photosynthetic and respiration rate using carbon and oxygen based methods, and at the same time, independent experiments for nitrogen assimilation and regeneration process measurement were conducted using stable isotope tracers. The differences of N assimilation and regeneration results between each method were analyzed in the context of hypoxic condition development.