Lake Plußsee is a small eutrophic kettle lake in northern Germany. Because it is sheltered and has no inflow from rivers, the Plußsee exhibits stable stratification and is especially suitable for limnological studies. This book presents the results of extensive research conducted on the ecophysiology of microorganisms - principally bacteria - at the Plußsee over the past several decades. It begins with three chapters on the general limnological state of the lake: physical factors, inorganic nutrients, plankton composition and succession, fish fauna, etc. These chapters are followed by discussions of dissolved organic matter and photosynthetic production of organic matter by phytoplankton. The remainder of the book addresses the dynamics of structure, function and metabolism of the microorganisms in the Plußsee.