Mussel Status

The earliest historical information regarding mussel species dates to 1874 when 47 different species are identified. In 1966, when William C. Starrett of the Natural History Survey conducted a comprehensive survey of the Illinois River from Dresden to Grafton, he finds 4,249 live mussels from 23 species, less than half the number identified earlier. Of the 23 species identified, five are represented by a single specimen (Cummings 2003). Thus, from 1874 to 1966, the Illinois River changes from an excellent to a poor stream for mussels. Starrett blames the changes on a combination of domestic, industrial, and agricultural pollution, including sedimentation. Table 44 illustrates the changes that have occurred from 1912 to 1969.

Table 44. Numbers of kinds of mussels living in various parts of the Peoria navigation pool of the Illinois River in 1912, the 1924-1925 period, and the 1966-1969 period (Starrett 1971)

In 1971, William Starrett publishes an article titled “Survey of the Mussels (Unionacea) of the Illinois River: a Polluted Stream.” He provides extensive data that document the decline of mussel species from 1870 to 1969. Table 45 shows the results of his work: 24 species are present in all three reporting periods, 21 species are present in the first two reporting periods but not the last, and four species are found only in the 1870-1900 period.

Table 45: Mussel Fauna of the Illinois River in Three Periods (Starrett 1971)

Key P Present; - Absent