Introduction This book contains papers given at a NATO Advanced Research Institute (A.R.I.) held at Caiscais, Portugal, in November, 1981. The subject of the A.R.I. was marine heterotrophy; this is defined as the process by which the carbon autotrophically fixed into organic compounds by photosynthesis is transformed and respired. Obviously all animals and many microbes are heterotrophs but here we will deal only with the microbes. Also, we restricted the A.R.I. primarily to microbial heterotrophy in the water column even though we recognize that a great deal occurs in sediments. Most of the recent advances have, in fact, been made in the water column because it is easier to work in a fluid, apparently uniform medium. The reason for the A.R.I. was the rapid development of this subject over the past few years. Methods and arguments have flourished so it is now time for a review and for a sorting out. We wish to thank the NATO Marine Science Committee for sharing this view, F. Azam, A.-L. Meyer-Reil, L. Pomeroy, C. Lee, and B. Hargrave for organizational help, and H. Lang and S. Semino for valuable editing aid.

Inhalt
Microbial Processes in the Sea: Diversity in Nature and Science.- Strategies for Growth and Evolution of Micro-organisms in Oligotrophic Habitats.- Physiological and Biochemical Aspects of Marine Bacteria.- Substrate Capture by Marine Heterotrophic Bacteria in Low Nutrient Waters.- Inputs into Microbial Food Chains.- Dynamics of Pools of Dissolved Organic Carbon.- Sinking of Particulate Matter from the Surface Water of the Ocean.- Measurement of Bacterioplankton Growth in the Sea and Its Regulation by Environmental Conditions.- Adenine Metabolism and Nucleic Acid Synthesis: Applications to Microbiological Oceanography.- Measurements of Bacterial Growth Rates in Some Marine Systems Using the Incorporation of Tritiated Thymidine into DNA.- Bacterial Growth in Relation to Phytoplankton Primary Production and Extracellular Release of Organic Carbon.- Diel and Seasonal Variation in Growth Rates of Pelagic Bacteria.- Organic Particles and Bacteria in the Ocean.- Nutrient Interactions and Microbes.- Heterotrophic Utilization and Regeneration of Nitrogen.- A Review of Measurements of Respiration Rates of Marine Plankton Populations.- The Use of Tracers and Water Masses to Estimate Rates of Respiration.- Protozoan Bacterivory in Pelagic Marine Waters.- Effect of Grazing: Metazoan Suspension Feeders.- The Use of Large Enclosures in Marine Microbial Research.- Lipid Indicators of Microbial Activity in Marine Sediments.- Aspects of Measuring Bacterial Activities in the Deep Ocean.- Bacterial Biomass and Heterotrophic Activity in Sediments and Overlying Waters.- Synthesis of Carbon Stocks and Flows in the Open Ocean Mixed Layer.- Contributors.