This Environmental Protection Agency manual was developed to provide pollution biologists with the most recent methods for measuring the effects of environmental contaminants on freshwater and marine organisms. The sections of this manual include: (1) Biometrics; (2) Plankton; (3) Periphyton; (4) Macrophyton; (5) Macroinvertebrates; (6) Fish; and (7) Bioassay. Each of these sections is divided up into chapters. The Biometrics section deals primarily with introductory statistics. The section discussing Plankton covers sample collection, preservation, prepartion, analysis and biomass determination. Sample collection, preservation, analysis, and preparation for Periphyton and Macrophyton are covered in those respective sections. In the section on Macroinvertebrates, selection of sampling sites, sampling methods, and data evaluation are described. Also in this section, a taxonomic bibliography for the Microinvertebrate groups is included. In the Fish section, sample collection, preservation and analysis is discussed among other things. In the final section, bioassay techniques for Phytoplankton, Periphyton, Macroinvertebrates, and Fish are described and the Flathead Minnow and Brook Trout Chronic Tests are included. References are given in all of the above sections. (MR)