Abstract
Abstract. The photosynthetic performance of marine phytoplankton varies in response to a variety of factors, environmental and taxonomic. One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis–irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data. The MAPPS P-E database, which consists of over 5000 P-E experiments, provides information on the spatio-temporal variability in the two P-E parameters (the assimilation number, PmB, and the initial slope, αB, where the superscripts B indicate normalisation to concentration of chlorophyll) that are fundamental inputs for models (satellite-based and otherwise) of marine primary production that use chlorophyll as the state variable. Quality-control measures consisted of removing samples with abnormally high parameter values and flags were added to denote whether the spectral quality of the incubator lamp was used to calculate a broad-band value of αB. The MAPPS database provides a photophysiological data set that is unprecedented in number of observations and in spatial coverage. The database will be useful to a variety of research communities, including marine ecologists, biogeochemical modellers, remote-sensing scientists and algal physiologists. The compiled data are available at https://doi.org/10.1594/PANGAEA.874087 (Bouman et al., 2017).
Highlights
One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis– irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data
Global estimates of marine primary production tend to converge on a number around 40–50 GT yr−1, the accuracy and precision on regional scales of the estimation protocols remain relatively poor, partly as a result of an incomplete understanding of how the photosynthetic performance of marine phytoplankton varies in the global ocean (Carr et al, 2006; Lee et al, 2015)
Photosynthesis–irradiance (PE) parameters derived from carbon uptake experiments conducted over a controlled range of available-light levels provide a means of comparing the photosynthetic characteristics of marine phytoplankton across different natural populations and cultured isolates (Platt and Jassby, 1976; Prézelin et al, 1989; MacIntyre et al, 2002)
Summary
Global estimates of marine primary production tend to converge on a number around 40–50 GT yr−1, the accuracy and precision on regional scales of the estimation protocols remain relatively poor, partly as a result of an incomplete understanding of how the photosynthetic performance of marine phytoplankton varies in the global ocean (Carr et al, 2006; Lee et al, 2015). The study noted that the presence of the accessory pigment chlorophyll b could lead to an underestimation of chlorophyll a concentration by 2–19 % (Martoura et al, 1997) This potential source of bias in fluorometrically determined chlorophyll a concentration would result in an overestimation of the chlorophyll a normalised photosynthetic parameters of up to 19 % where relative chlorophyll b concentrations are high (e.g. the deep chlorophyll maxima of the subtropical gyres). Data were fit to the threeparameter function of Platt et al (1980), which describes the decrease in photosynthetic rate with irradiances much higher than saturating light levels, as follows:. Units Decimal degrees Decimal degrees m mg Chl a m−3 mg C (mg Chl a)−1 h−1 (μmol quanta m−2 s−1)−1 mg C (mg Chl a)−1 h−1 μmol quanta m−2 s−1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
