Strong winds sweep over the Rhön, a vast region of rolling, forested hills and pastureland in central Germany. Undeterred, Stefan Zaenker, leading a group of four volunteers, runs through his checklist alongside a forest road. Are rubber boots disinfected to prevent introducing potentially harmful microorganisms into the wetland? Are the team app and GPS functioning correctly? Have enough flags been packed? When all is in order, Zaenker, 56, leads the group into a soggy alder forest. Its mission for the day: to locate and map as-yet-undiscovered springs and document any species inhabiting them.
As a senior conservation official for the state of Hesse, Zaenker considers springs so important for human life and biodiversity that he — along with volunteers from the Hesse Association for Cave and Karst Research — spends much of his spare time conducting large-scale searches for them in the Rhön, which includes the German states of Bavaria, Thuringia, and Hesse, and in a nearby national park. Conservation strategies around the globe focus on rivers, bogs, forests, reefs, and many other habitat types. Springs rarely get any special attention. In the United States, for example, springs do “not appear to be a prominent feature on the conservation radar,” says Kirsten Work, a zoologist from Stetson University in DeLand, Florida. Springs are home to highly specialized species, some of which live outside by night and in the darkness of groundwater by day. But for the biosphere, these tiny spots dotted across Earth’s land surface play a powerful role: They connect reservoirs of groundwater to the outside, sunlit world. Only so-called “fossil” aquifers — ancient bodies of groundwater that do not recharge — lack a link with the surface. Without a continual connection to groundwater, which also feeds rivers, many landscapes would quickly dry up and become hotter. In addition, springs are home to a wide range of highly specialized species, some of which live outside by night and in the darkness of groundwater by day.
Far too little is known about where springs occur and what species they harbor, Zaenker says. In a country like Germany, which has no wilderness but a very efficient bureaucracy, most people assume that everything in nature has already been discovered and mapped. This is not true, he claims: “I can stand right next to an impressive spring with water flowing out, but the official topographical map shows nothing.” Official maps denote springs with a blue dot, indicating they are habitats protected by law. Yet many — if not most — springs remained undocumented. “How are we going to effectively protect these important habitats or know if they dry up,” asks Zaenker, “if we don’t even know they exist?”
After an hour of scouring the alder forest, the team has found and marked with flags eight new so-called helocrene springs, where water seeps diffusely from the ground into a marsh or bog. To the average person, they can look like puddles. But Zaenker recognizes much more in them. “See the bright green plant?” he points out. “That’s the alternate-leaved golden saxifrage, a species typical for springs.” The team logs the flags’ positions in a database, then measures pH levels and electrical conductivity to assess the water’s acidity and dissolved particle content. They collect water samples, identify more plants, and sift through leaves to find insects, mollusks, and crustaceans unique to these habitats.
Halfway around the globe, ecologist Larry Stevens is on a similar mission and is equally worried about the future of springs. In 2013, Stevens cofounded the Springs Stewardship Institute, a nonprofit science initiative linked with the Museum of Northern Arizona, and in 2023 he published Springs of the World: Distribution, Ecology, and Conservation. Stevens considers springs prime examples of “canaries in coal mines” because they act as early warning systems of water table decline and biodiversity loss. Some experts use springs as sentinels for aquifer health, observing whether their temperatures increase or their discharges fall. Stevens is particularly fascinated by the large number of highly specialized and endemic species found in and around springs. He points out that with constant temperatures and high purity, spring water offers unique living conditions. Springs are often isolated from one another geographically and many have been in place for millennia, characteristics that make them hotspots for new species to arise and refuges for species that have lost their habitats elsewhere.
“Although miniscule in habitat area compared to rivers, lakes, and oceans, springs support more than 10 percent of U.S. endangered species, as well as thousands of other rare and endemic biota,” he notes. For example, the so-called Comal Springs riffle beetle is limited to a few springs in Texas, while the endangered White River springfish lives only in isolated warm springs in eastern Nevada.
