Chlorophyll Fluorescence Terminology: An Introduction -- In Situ Measurement of Variable Fluorescence Transients -- Overview of Fluorescence Protocols: Theory, Basic Concepts, and Practice -- Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation -- Microscopic Measurements of the Chlorophyll a Fluorescence Kinetics -- Estimating Aquatic Productivity from Active Fluorescence Measurements -- Taxonomic Discrimination of Phytoplankton by Spectral Fluorescence -- Flow Cytometry in Phytoplankton Research -- The Use of the Fluorescence Signal in Studies of Seagrasses and Macroalgae -- Chlorophyll Fluorescence in Reef Building Corals -- Assessing Nutrient Status of Microalgae Using Chlorophyll a Fluorescence -- The Application of Variable Chlorophyll Fluorescence to Microphytobenthic Biofilms -- Chlorophyll Fluorescence Applications in Microalgal Mass Cultures -- Delayed Fluorescence -- The Study of Phytoplankton Photosynthesis by Photoacoustics. Measurements of variable chlorophyll fluorescence have revolutionised global research of photosynthetic bacteria, algae and plants and in turn assessment of the status of aquatic ecosystems, a success that has partly been facilitated by the widespread commercialisation of a suite of chlorophyll fluorometers designed for almost every application in lakes, rivers and oceans. Numerous publications have been produced as researchers and assessors have simultaneously sought to optimise protocols and practices for key organisms or water bodies; however, such parallel efforts have led to difficulties in reconciling processes and patterns across the aquatic sciences. This book follows on from the first international conference on "chlorophyll fluorescence in the aquatic sciences" (AQUAFLUO 2007): to bridge the gaps between the concept, measurement and application of chlorophyll fluorescence through the synthesis and integration of current knowledge from leading researchers and assessors as well as instrument manufacturers.