On the move
Biologists say the snails are on the move, and quickly
reproducing, so something needs to be done quickly.
The eco-system of the lake, called Lake Brantly, is very delicate.
An eco-system is the balance between everything living in a given environment.
If you add creatures from elsewhere, or kill off any creatures or plants that are there, you can upset the balance which has serious consequences for all living things.