This text has been prepared as part of an extensive water quality monitoring programme presently being developed for mussel growers in the Atlantic Maritime Provinces. Its purpose is to introduce non-biologists, specifically practicing mussel culturists, to the subject of mussel biology as it applies to the culture of the blue mussel, Mytilus edulis. Its intent is to describe, in layman's terms, the major biological concepts necessary to understand how mussels live, grow, and reproduce, and the major environmental factors that determine the rate at which these processes occur, so that growers participating in the monitoring programme will better understand the logic and concepts behind the various monitoring tasks. It does not deal with the technical aspects of mussel culture.

The manual is organized into three major sections. The first section deals with the general biology of mussels in terms of their taxonomy, anatomy and physiology. The concepts presented here are important to understanding the way mussels are affected by the environment in which they live and how they in turn affect their environment. The second section deals with the ecology of mussels and the physical, chemical and biological environmental factors currently thought to be most important in controlling the settlement, growth and survival of mussels. Measurement of these factors constitutes the core of the monitoring programme. The last section provides a general description of the techniques being employed in the monitoring programme, but does not attempt to provide step-by-step instructions. The latter is the subject of another manual that should be considered supplementary to this one.

We have attempted to present this information in layman's terms, assuming that most mussel growers will not have had a strong background in biology, but with enough detail to cover the topics in a more than superficial way. There are many technical terms used by biologists. No attempt has been made to avoid the use of these terms since it is important that mussel growers are familiar with them and understand the concepts behind their use. Only in this way will growers be able to converse intelligently with biologists and gain a better understanding of the biological and environmental factors important to the successful cultivation of mussels. In addition, familiarity with scientific terms and concepts will allow growers to better convey to biologists the many invaluable observations they make during the long hours spent in the field while growing mussels.

To help ease the task of learning new terminology, all scientific and technical terms have been gathered together in a glossary presented at the end of the text. When a scientific term is first used it is underlined and the page on which it is first used is indicated in the glossary. In this way the glossary also serves as a simple index.