Lakes that have no inlet/outlet essentially have no "Currents". Even big lakes with inlet and outlet have little current except near the stream areas. The surface water
to about 2' is mixed by heavy winds and spring areas have some upwelling,
but there is NO CURRENT. Even where there is current, once the female establishes the "tube" the drift will take the eggs uniformly downcurrent together. Turnover may expand the bottom of the tube a little by churning the bottom,but the bloodworms settle back in the same relative area.

If you had ever hit on a honey hole and caught fish after fish from the same relative
area you may have wondered WHY one particular spot held so many fish.
Now you know....the food source waz there.