Ecophysiology of a marine ultramicrobacterium

It is generally assumed that the oceanr epresentsa marine desert. Indeed, the ocean is responsible for only one-third of the world's primary production, whereas it represents twothirds of its surface. However, the oceanic phytoplankton biomass equals only 0.05% of the terrestrial biomass. Therefore, per unit of biomass, oceanic ecosystems are far more productive than terrestrial systems and tumover rates of nutrients in the ocean are accordingly several hundred times higher. Interestingly enough, bacteria dominate the biomass of the oceans, partly because they out-compete the phytoplankton for nutrients. As a result, marine bacteria act as nutrient reservoirs, especially in oceanic regions where extremely low-nutrient conditions prevail. Marine bacteria therefore control the primary production. An overview of the different studies that have been performed on low-nutrient-adapted bacteria and of the ecological significance of marine bacteria is presented in Chapter 1. ... Zie: Summar