Survey of bottom-up controls of Emiliania huxleyi in the Northeast Subarctic Pacific

In contrast to the North Atlantic, there are few studies of the coccolithophore Emiliania huxleyi in the Northeast Subarctic Pacific. Yet, recent observations in this area suggest that during spring E. huxleyi is more important than previously thought. To survey potential bottom-up controls of E. huxleyi, seawater samples were collected from the surface layer in the Northeast (NE) Pacific, mainly during June 2001. Average surface mixed layer irradiance, temperature, salinity, nutrient concentrations (nitrate, phosphate, silicate), and abundances of E. huxleyi were determined. Data were partitioned among high nutrient-low chlorophyll (HNLC) waters and mesoscale eddies that carry waters enriched with macronutrients and iron. No significant differences existed between HNLC waters and mesoscale eddies, with respect to relationships among E. huxleyi abundance and physical and chemical parameters. All chemical and physical parameters, except underwater irradiance, were significantly inter-correlated. E. huxleyi represented up to 67%, but generally <10%, of autotrophic carbon. Abundances were highest at lower temperatures and higher nutrient concentrations, underwater irradiance, and salinity.