MEPS 311:37-46 (2006)  -  doi:10.3354/meps311037

ABSTRACT: Comparisons of primary productivity measured by ¹⁴C uptake and fast repetition rate fluorescence (FRRF) for samples taken from Massachusetts Bay and Narragansett Bay demonstrated a linear relationship between the 2 techniques. The slope of the regression for different phytoplankton samples ranged between 0.23 and 1.04, with most between 0.4 and 0. The r² was usually high and >0.9 in the best cases. The results indicated that the FRRF usually underestimated primary productivity relative to ¹⁴C. The variability in the relationship between ¹⁴C uptake and the FRRF productivity estimates indicates that FRRF field measurements should be calibrated against other productivity measurement techniques such as ¹⁴C uptake or oxygen production if they are to be compared to historical productivity estimates. The Kolber & Falkowski (1993; Limnol Oceanogr 38:1646–1665) and the Smyth et al. (2004; J Plankton Res 19:1637–1670) models for estimating productivity by variable fluorescence were compared, and agreed very well with an r² of 0.99 for the linear relationship between the 2 techniques.

KEY WORDS: Variable fluorescence · Primary productivity · Fast repetition rate fluorescence · Phytoplankton