Photo
courtesy of Illinois Natural History Survey
Male and Female Higgins' Eye |
Life History: Glochidia, larval stages of the mussel, are released
by the female and must attach to the gills of the host
fish (sauger, walleye, freshwater drum, smallmouth
or largemouth bass) before dropping off several weeks later onto their "mussel bed."
What good are they?
* Provide cover for aquatic species
* Provide
food for fish and mammals
* Help biologists monitor
aquatic health of rivers
Where do they live?
Medium to large rivers with high current
Sand-mud-gravel substrate |
 Diagram
courtesy of North Carolina
Freshwater Mussel Life Cycle
|
Historic Distribution:
Mississippi
River in Pool 24 Louisiana, MO to Pool 3 Prescott, WI
Tributary rivers of the Mississippi
* Kankakee,
Sangamon, Rock, and Illinois rivers in IL
* Cedar,
Wapsipinicon and Iowa rivers in IA
*
St. Croix,
Wisconsin and Black rivers in WI
The best bed was in
Pool 10 near Prairie du Chien, WI - East Channel
Present Distribution:
Mississippi River from Pool 22 near
Hannibal, MO to Pool 7
St. Croix, Wisconsin, and Rock rivers |
Reasons
for Decline: Higgins’ eye were never common, but alteration
of habitat such as impoundment (dams), dredging, increased
turbidity (cloudiness of water), and sedimentation (displaced river bottom substrate) probably decreased their
range and abundance.
The greatest threat to their existence
occurred in the 1980’s with the introduction of
zebra mussels. This invasive species competes for food
and oxygen and can attach to the shells of native species
in large numbers. |
