Abstract:Because body size is closely related to metabolism, size spectrum is a powerful approach to understanding biological regularities of different organization levels, and can be used to effectively describe the status of ecosystems due to its merits compared with the approach of traditional taxonomy. Here we introduce the concepts, background and developmental history related to aquatic particle /biomass size spectrum. Size spectrum model contributes substantially to size spectrum theory, and a series of models including Sheldon-model and T-D model represent the basic developmental history of size spectrum theory, and constitute the framework of size spectrum theory. Modeling is still an effective way to probing the mechanism and impacting factors of size-spectrum formation in ecosystems or communities. Studies on benthic, planktonic, microbial and fish size-spectra were reviewed. Many theoretical and experiential studies on plankton size spectra supported the consensus that energy is allocated to the entire organism community by a highly organized manner in the stable tropical or subtropical oceanic area, which is in favor of a regular size structure that can maintain stability over time. However, size spectra are less regular in temperate and polar sea, and lakes, rivers, estuarine and coastal waters where there is strong interaction between land and water. Benthic size spectra were more irregular and complex compared with planktonic size spectra. Easily-disturbed habitat, strong interaction between solid and liquid, and component organisms dominated by grazers and saprophagous organisms may be reasons for this irregularities and complexities. Microbes(<200μm)and fish are the indispensable part of an integrated size spectra of a ecosystem, and generally represent the start and end of energy transfer, respectively. Microbes include diverse species with various feed types, which makes it is necessary to combine species classification with size determination for studies of microbial size spectra. Fish size spectrum is closely related to fishing levels, and able to reflect disturbance from human beings, therefore it can be used for the monitoring of aquatic environment and fishery resources. Although it is still controversial about some details of size spectrum theory, size spectrum theory has been applied in many fields, such as ecosystem description and monitoring. We analyzed the advantages and disadvantages of three methods of estimation of potential fish yield based on size spectrum theory. And with the application to estimating potential fish yield as the focus, applications of size spectrum theory were discussed. Then, the current status of size-spectrum studies in China was analyzed. Size-spectrum studies in China have been started, but it is still in early stage. It is proposed that more attention should be invested in this field. Finally, based on the relationship between metabolic theory, macroecology and size spectrum theory, the application of new size measurement methods, the relationship between traditional taxonomic approach and particle size approach, and the traits of size-spectra modeling, the prospect of particle/biomass size spectrum study was proposed. We proposed that new development in metabolic theory and macroecology, and the application of new size measurement methods are bound to promote new discoveries in size spectra. The combination between traditional taxonomy, size spectrum, and modeling will be an important approach to future size spectrum study.