Seasonal variations in physiological parameters of phytoplankton across the North Atlantic

Abstract

Variations in the shapes of the action and absorption spectra, and the physiological parameters of phytoplankton (a, the biomass (B)-specific initial slope of the photosynthesis-irradi- ance curve; PS,, the plateau of the curve; m, the maximum quantum yield of photosynthesis), were studied. Data were collected in the North Atlantic in five biogeochemical provinces for two seasons: in fall of 1992 and spring of 1993. Further, some nine independent variables were tested for their ability to predict the physiological parameters, using linear regression analyses. It was found that the parameters were more variable between seasons than between provinces, although the differences in the spectral shapes between provinces were significant. It was also shown that several independent variables (alone or in combination) were able to predict a significant fraction of the total variance in the parameters. However, the correlation between variables and parameters differed unsystemati- cally both between provinces and seasons. The results suggest that predicting a parameter from an independent variable would have to be carried out at a province level: the relationship changed or disappeared when data from two or more provinces were pooled.