Last week, I was visiting my field sites to collect invertebrates and download data. While I was enjoying the fall weather, I got to thinking about losing streams. I don't mean that I was concerned about losing a stream; I'm talking about streams that have flowing water for a stretch and then, a short distance downstream, there is no water! In a losing stream, the water is "lost" into the groundwater system.
I have seen evidence that at least two of the streams that I am studying are losing streams: Deer Creek and Hamilton Creek. I've even taken video of this phenomenon at one of the sites:
I am often awestruck by the complexity of nature. The phenomenon of losing streams - which often resurface from a spring a short distance away - is one of these complexities. It isn't that the concept is complex, but rather the implications of the existence of these streams. When the water is lost, that segment of stream changes from an aquatic ecosystem to a terrestrial ecosystem. This removes habitat from one set of species (which may or may not escape the loss of water) and temporarily creates a completely new type of habitat. Also, a path of dry land is created that permits the movement of small terrestrial animals (eg., spiders, ants, and flightless beetles) across what is otherwise an impassable boundary. And then there are the questions of how this may impact the chemical composition of groundwater, especially in streams that carry runoff that is polluted by human activities.
Missouri is home to many losing streams, especially in the Ozarks where much of the bedrock is limestone. Limestone is relatively easily weathered or dissolved, resulting in an abundance of sinkholes and caves. The predominance of this type of rock is one of the reasons that Missouri has claimed the moniker "The Cave State". The Missouri Department of Natural Resources has many interesting resources if you'd like to read more about caves, springs, and losing streams in the state.