Temporal Variability in Elemental Composition of Particulate Organic Nutrients along the Southern
California Coast
Jeremy S. Huang
Mentor: Adam C. Martiny
Water along the Southern California coast exhibits a great deal of deep water replacement when strong winds
push surface water offshore. This phenomenon, known as upwelling, describes the upward movement of
cold nutrient-rich water towards the surface. The influx of nutrient-rich water leads to an increase in
phytoplankton population and productivity. Because upwelling strength varies throughout a year, California
displays “oceanic seasons.” The Redfield ratio states that there is an average stoichiometric ratio of carbon,
nitrogen, and phosphorus found in phytoplankton in deep ocean waters. This ratio, found to be C:N:P =
106:16:1 is the foundation of ocean biogeochemistry. Because phytoplankton control the regeneration and
cycling of nutrients, deviations in the Redfield ratio can be attributed to changes in the phytoplankton
community. Measuring the elemental ratios of phytoplankton along the coast is important to fully understand
biogeochemical cycles in Southern California. In this study, we measure concentrations of particulate organic
carbon (POC), nitrogen (PON) and phosphorus (POP), as well as inorganic nitrogen and phosphorus
concentrations at the time series station MICRO (Microorganisms in the Coastal Region of Orange County)
at Newport Beach. We predict a CNP ratio of 137:18:1 as described by Martiny et al., 2013. We also
hypothesize a variation in nutrient concentration and uptake by phytoplankton between different seasons.
Data of two years show a particulate C:N:P ratio of 103:14:1. We see a clear trend of variability in particulate
matter concentration throughout seasons. However, there is no evidence of variability among nutrient ratios
across seasons.