Equatorial Pacific Macronutrient Regimes and Autotrophic Biomass

Thumbnail Image
Dixon, Paul
Issue Date
Oceanography , Scholarship Sewanee 2010 , Climate change , Nutrients , Redfield
Oceanic primary production plays an important role in the global carbon cycle. This project investigated the relationship between macronutrient concentration and primary production in the Eastern Equatorial Pacific Ocean. Both a Redfield nutrient regime and a correlation between macronutrient levels and autotrophic biomass were expected. An analysis of macronutrient (nitrate, phosphate, and silicate) concentrations and fractionated chlorophyll fluorescence was performed on water samples from the upper 400m of the water column with a focus on the deep chlorophyll maximum. For all samples (n=151), the nitrate to phosphate ratio was 14.86 (R2=0.44) and the silicate to phosphate ratio was 7.85 (R2=0.51). This supports Redfield’s theory of biological control of pelagic nutrients, although the data reveals geological contributions as well, especially for silicate. No correlation was found between nutrient levels and autotrophic biomass, which could indicate iron limitation in the sampling region.