Jul 20, 2004 — You can hear frogs croaking and chirping in the middle of a city these days. You can see cattails and water lilies out your window even if you live nowhere near a lake. Water gardens are all the rage. But some scientists are warning that we have to be careful with our gardens. If plants or animals get out of a backyard pond, they can endanger native species. the Great Lakes Radio Consortium's Chris Julin reports.