Premium
THE RELATIONSHIP BETWEEN PHOTOSYNTHESIS AND LIGHT FOR NATURAL ASSEMBLAGES OF COASTAL MARINE PHYTOPLANKTON 1
Author(s) -
Platt Trevor,
Jassby Alan D.
Publication year - 1976
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1976.tb02866.x
Subject(s) - phytoplankton , biology , uncorrelated , photosynthesis , saturation (graph theory) , range (aeronautics) , chlorophyll a , atmospheric sciences , zoology , statistics , botany , ecology , physics , mathematics , nutrient , materials science , combinatorics , composite material
SUMMARY In a series of 188 experiments on the, light‐saturation curve for natural assemblages of phytoplankton at 3 stations in Nova Scotia coastal waters, it was found that both the initial slope (α) of the curve and the assimilation number ( P m B ) varied about 5‐fold throughout the year. No differences could be detected between stations, but both α and P m B decreased with depth. The mean value of α for all the experiments was 0.21 mg C[mg Chl a] −1 · h −1 · W −1 · m 2 with a range from 0.03 to 0.63. An explanation is offered for the nonconstancy of a in terms of the effect of cell‐size and shape on self‐shading. An estimate is made from first principles of the physiological maximum‐attainable value of α. This estimate corresponds, within the limits of experimental error, to the highest values of α observed in the study. It is deduced that on the average the phytoplankton were photosynthesizing at only 44% maximum capacity. The mean value of P m B for all experiments was 4.9 mg C[mg Chl a] −1 · h −1 , with a range from 0.73 to 24.8. In the matrix of partial correlation coefficients, α and P m B were positively correlated with each other; α was correlated with mean solar radiation averaged over the 3 days prior to the experiment, but uncorrelated with temperature; P m B was correlated strongly with temperature but uncorrelated with recent solar radiation. The results show that P m B could be estimated from α and temperature using an empirical multiple regression equation, independent of depth. It is suggested that α and P m B are both correlated with some other factor not measured in the study, perhaps the mean cell‐size of the populations, or the nutrient status of the cells. The predictability of primary production is discussed in the light of this evidence.