I agree with Paul & Henk. A floating mussel is a dead mussel, even
though tissue is still inside the (generally thin) shell. In Texas, the
recent rains/flooding probably caused the situation. We also see this from
time to time here on the Mississippi River, particularly in spring, after
ice-out. If you just see floating mussel meats, then you have an entirely
different, and usually much more serious situation.
Marian
Marian E Havlik
Malacological Consultants
1603 Mississippi Street
La Crosse, WI 54601-4969
[log in to unmask]
P/F:608.782.7958