Paul G. Falkowski

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We assembled a dataset of 14C-based productivity measurements to understand the critical variables required for accurate assessment of daily depth-integrated phytoplankton carbon fixation (PP,,) from measurements of sea surface pigment concentrations (C,,,). From this dataset, we developed a light-dependent, depth-resolved model for carbon fixation (VGPM)(More)
In the modern ocean, a significant amount of nitrogen fixation is attributed to filamentous, nonheterocystous cyanobacteria of the genus Trichodesmium. In these organisms, nitrogen fixation is confined to the photoperiod and occurs simultaneously with oxygenic photosynthesis. Nitrogenase, the enzyme responsible for biological N2 fixation, is irreversibly(More)
Contributing roughly half of the biosphere's net primary production (NPP), photosynthesis by oceanic phytoplankton is a vital link in the cycling of carbon between living and inorganic stocks. Each day, more than a hundred million tons of carbon in the form of CO2 are fixed into organic material by these ubiquitous, microscopic plants of the upper ocean,(More)
The eukaryotic green alga Dunaliella tertiolecta acclimates to decreased growth irradiance by increasing cellular levels of light-harvesting chlorophyll protein complex apoproteins associated with photosystem II (LHCIIs), whereas increased growth irradiance elicits the opposite response. Nuclear run-on transcription assays and measurements of cab mRNA(More)
Atmospheric reactions and slow geological processes controlled Earth's earliest nitrogen cycle, and by ~2.7 billion years ago, a linked suite of microbial processes evolved to form the modern nitrogen cycle with robust natural feedbacks and controls. Over the past century, however, the development of new agricultural practices to satisfy a growing global(More)
We describe a classification system for daily phytoplankton primary productivity models based on four implicit levels of mathematical integration. Depth-integrated productivity models have appeared in the literature on average once every 2 years over the past four decades. All of these models can be related to a single formulation equating depth-integrated(More)
Over the past three decades, massive bleaching events of zooxanthellate corals have been documented across the range of global distribution. Although the phenomenon is correlated with relatively small increases in sea-surface temperature and enhanced light intensity, the underlying physiological mechanism remains unknown. In this article we demonstrate that(More)
We analyzed the cellular content of C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Cd, and Mo in 15 marine eukaryotic phytoplankton species in culture representing the major marine phyla. All the organisms were grown under identical culture conditions, in a medium designed to allow rapid growth while minimizing precipitation of iron hydroxide. The cellular(More)
Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis, the evolution of which transformed the biology and geochemistry of Earth. The rapid increase in published genomic sequences of cyanobacteria provides the first opportunity to reconstruct events in the evolution of oxygenic photosynthesis on the scale of entire genomes. Here, we(More)
The vertical distribution of bacteriochlorophyll a, the numbers of infrared fluorescent cells, and the variable fluorescence signal at 880 nanometers wavelength, all indicate that photosynthetically competent anoxygenic phototrophic bacteria are abundant in the upper open ocean and comprise at least 11% of the total microbial community. These organisms are(More)