Coastal nitrogen drives respiration quotient in the Southern California Bight

Abstract

Southern California Bight coastal waters are dynamic and strongly influenced by a changing climate. In the open ocean, an increased respiration quotient has been found during high temperature and low nitrogen conditions but variation in coastal environments is uncertain. To disentangle the controlling factors in a coastal environment, we examined environmental conditions, particulate organic matter, and the respiration quotient over five years in the Southern California Bight. Our study revealed clear seasonal variation in environmental conditions and biological parameters. We detected a higher than previously reported respiration quotient in open ocean regions. We found a strong inverse relationship between the respiration quotient, nitrate and chlorophyll. Our findings also suggest that changes in community structure, triggered by nutrient shifts and a local oil spill, affected the respiration quotient range and explains some of the variability measured. As climate continues to impact coastal regions, a variable respiration quotient is likely important for subsurface oxygen concentrations and in turn the health of our coastline.