ABSTRACT
All aquatic bodies in the world, from the smallest forest ponds to the open ocean, house complex and diverse microbial ecosystems. When it comes to things such as number of species and carbon and nutrient turnover, unicellular organisms completely dominate many aquatic ecosystems, and organisms on the size scale of fish are only minor players, contributing little to the overall balance. In environments dominated by open water, such as marine systems and those of large lakes, most of the photosynthetic activity is carried out by microscopic phytoplankton cells. In many ways, the microbial biota is as fascinating and complex as the apparently more flashy systems of tropical forests or coastal marine macroscopic ecosystems.
