Molecular Ecology of Phytoplankton Photosynthesis

Abstract

The ability to derive basin-scale maps of phytoplankton chlorophyll in the upper ocean from satellite color sensors (see Lewis, this volume) has led increasingly to the development of models relating biomass to primary production (Eppley et al., 1985; Falkowski, 1981; Platt, 1986; Platt and Sathyendranath, 1988; Morel, 1991). Chlorophyll, however, represents a pool size, while primary production is a flux. To derive a flux from a pool, a time-dependent variable must be incorporated. The simplest models relating carbon fixation to chlorophyll incorporate irradiance (Bidigare et al., this volume); the transfer function is a quantum yield. These so-called light-chlorophyll models (Ryther and Yentsch, 1957; Cullen, 1990) are virtually impossible to verify in the ocean, hence their credulity presumably lies in understanding the underlying biological processes and how those processes are regulated. Here, I examine how some of the key parameters which are implicitly or explicitly incorporated in rational light-chlorophyll models are regulated at a fundamental, molecular level.