Freshwater Mussels Mussels have much to teach us about the health of our watersheds. These bivalves play important roles in freshwater systems. This book is about mussels and the life cycle of a freshwater mussel which is quite complex. Freshwater mussels play a number of important roles in aquatic ecosystems. As sedentary suspension feeders, unionoids remove a variety of materials from the water column, including sediment, organic matter, bacteria, and phytoplankton. Types of Mussels Where the live Their background Do they help or hurt their environment