In colder winters than we are currently experiencing in Vermont, small streams wear thick layers of ice. In the winter of 1997 I attempted to sample some streams year round. I was thwarted by ice so thick that a felling axe made little impression. But spring-fed streams with an endless supply of water at a constant temperature shrug off any ice that may form. These unique flowing-water habitats lack the minute bits of organic material that feed insects in other streams. And so many species simply cant live in springs, freeing up those habitats for spring water specialists found nowhere else.

The art for this episode is a photo of the Well of Dee, the source of Scotland's River Dee. The river emerges from the ground as a large spring in Cairngorms National Park and flows west to the North Sea at Aberdeen. The art is from Wikimedia Commons and full details are here: https://commons.wikimedia.org/wiki/File:Well_of_Dee_-_Source_of_River_Dee_-_geograph.org.uk_-_229032.jpg