Thus, these mussels can be used to judge stream quality or the degree of degradation. It is especially meaningful to follow changes in mussel populations over time. Because our predecessors assembled systematic collections that have been carefully maintained and because of the extensive efforts of the authors and others to reexamine watersheds and relocate previously known localities for some species, we have a better understanding of trends regarding species distribution and populations. This knowledge offers little encouragement or cause for contentment, however, because more than half of the mussel species of the Midwest are threatened or endangered. No other major group of midwestern animals is so imperiled.
Identification is usually the essential first step to unlocking information about a species.
For this reason, this field guide includes color photographs and maps to assist the user in identifying mussels with a minimum of effort and specialized knowledge. I believe the user will find this approach a utilitarian one that will lead to new knowledge of, and appreciation for, this important group of organisms.