Diversity of marine phototrophs

Abstract

Phototrophs transform the energy of solar irradiation into chemical-bond energy in organic substances. Those organic substances provide biological energy not only for the activities of life on Earth, but also the formation and maintenance of regional and/or global ecosystems. They also provide biotechnological resources for materials, energy, and so on. Since their energy transformation is the starting point of the energy flow in the marine ecosystem, the understanding of phototrophs is important not only for the consideration of the homeostasis of the marine environment, but also for the development of new marine biotechnologies.Traditionally, diatoms and flagellates had been understood to be the major primary producers in the ocean. However, the developments of technologies for phytoplankton research within the past three decades revealed a diversity of phototrophs serving as primary producers and contributing to the transformation of light-energy into the chemical energy. The contribution by those diverse phototrophs to the energy flow in the ocean seemed much larger than that by diatoms and flagellates, which indicated the necessity of reconsidering energy flow or primary production. In this paper, the author discusses the diversity of planktonic phototrophs that serve as the primary producers (the starting point of the energy flow in the marine environments) based on research results in chronological order.