Flip over a rock in a stream and you may reveal some interesting aquatic invertebrates. Dig deeper into the gravel below and adjacent to the stream and you may find groundwater organisms more akin to cave-adapted species than stream dwellers. This habitat, called the hyporheic zone, is a transition between surface water and deeper groundwater. It can contain rare and unusual, blind and albino organisms like those found in springs, wells, and caves. However, because of its’ inaccessibility, little is known about the habitat or the organisms found there. Sampling requires hammering a metal spike several feet into the cobbles. This spike is hollow and perforated at the bottom. When a hand pump is mounted to the spike, water, and the organisms that live in it, can be pumped out. Although biologists have been using this instrument, called a Bou-Rouch pump, in Europe for decades, research in the United States and most other countries has been rare. In Texas, the hyporheic zone has only been sampled a handful of times, in a handful of places. Even with this limited-effort, biologists have collected rare and undescribed groundwater organisms.
For the first time, biologists from Texas Parks and Wildlife and Texas State University are taking a closer look at this habitat in Texas. In addition to surveying the organisms present, biologists are also measuring a suite of physical and chemical parameters to better characterize the habitat. It may turn out that some of the residents of the hyporheic zone are not as rare as previously thought: just that no one has looked closely for them. These organisms may also reveal important information about the health of our beautiful Texas springs. Because this research is just beginning, it is far too early to make any conclusions, but keep an eye on Frontiers in Texas Biodiversity for future updates.