Nitrogenous nutrition of phytoplankton from the Northeastern subarctic Pacific Ocean ...

• Main Author: Varela, Diana Esther
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Pacific; Subarctic
• Online Access: https://dx.doi.org/10.14288/1.0053280; https://doi.library.ubc.ca/10.14288/1.0053280

The goals o f this thesis were to investigate the uptake rates of inorganic and organic forms of nitrogen, the relative proportions of new and regenerated primary production, and the interactions between uptake of ammonium and nitrate by phytoplankton from the NE subarctic Pacific Ocean. Nitrogen uptake rates, and physical, chemical and biological characteristics of the euphotic zone were studied during winter, spring and late summer for two years along a transect extending from 49°N, 127°W to 50°N, 145°W. New and regenerated primary production were estimated by means of 1 S N isotopes. Ammonium (NH₄⁺) was usually taken up at the highest rates throughout the euphotic zone during all seasons. Urea uptake rates were lower than those of NH₄⁺, but higher values were occasionally observed, particularly during the spring of 1993. Nitrate (N0₃⁻) uptakerates represented on average 21% of the depth integrated total nitrogen uptake, both longitudinally and seasonally. The ∫ - ratio was overestimated on average by 36% ...