Aquatic life in groundwater explored
Groundwater is also an ecosystem, but little is known about its biodiversity. In a pilot study, Eawag researchers have now documented the diversity of life in Swiss groundwater - and discovered previously unknown species of psyllid. The Eawag researchers adopted a citizen science approach.
With a length of two centimeters, amphipods are not particularly large even in surface waters, but in groundwater they are tiny. There, they usually measure between one and ten millimeters. A team led by Prof. Florian Altermatt of the Swiss Federal Institute of Aquatic Science and Technology (Eawag) has investigated the species of psyllid and other organisms found in Swiss groundwater - and discovered four new species.
The fact that groundwater also represents an aquatic habitat has been known and documented for some time in certain regions of Europe. But, says Roman Alther, lead author of the study, "Knowledge of the diversity of subterranean organisms is still fragmentary, even in a country like Switzerland, where wildlife is relatively well studied." Now, basic knowledge about the diversity of life underground is to be established in Switzerland. "It's important to protect this biodiversity, too," says biologist Alther, "because underground ecosystems provide important services for us, such as drinking water." As a reminder, around 80 percent of drinking water in Switzerland is obtained from groundwater.
New flea cancers discovered
In their pilot study, Florian Altermatt's group has now laid the first stone of a nationwide inventory. Groundwater samples from 313 sites in the cantons of Aargau, Basel-Landschaft, Solothurn and Zurich revealed a diverse aquatic fauna that had not been documented before: including organisms from various important groups of invertebrates, especially crayfish. The researchers were particularly interested in the cave amphipods (Niphargus), a genus of amphipods. Individuals of eight species were found in the groundwater samples, two of which (N. fontanus and N. kieferi) were found for the first time in Switzerland. In addition, the researchers discovered four phylogenetic lineages previously unknown to science, which may be new species. One of these has now been formally described as the new species Niphargus arolaensis, the Aare groundwater flea crab.
Collaboration with drinking water supply practitioners
One of the special features of the groundwater fauna study is the way in which the researchers proceeded with data collection: They relied on the assistance of well masters to collect groundwater samples. To publicize the research project among drinking water suppliers, the project was presented in personal letters, at a symposium and in direct talks. With resounding success: of 130 well masters who showed a closer interest in the project, 82 finally agreed to take samples.
The well masters had to proceed according to a precisely defined protocol and use sampling material supplied by the researchers. The most important step was to attach a filter bag to the drainage pipes through which the groundwater flows into the well pits. All the material that washed in from the groundwater layer during a week was collected in it. Afterwards, the well masters removed all living organisms from the bags and sent them, packed in a container filled with ethanol, to Eawag. "The interest and helpfulness we encountered from the well masters was fantastic," says Roman Alther.
The Citizen Science Approach with a selected group of citizen scientists will also be part of the already planned expansion of the project. Over the next few years, data will be obtained from several hundred well pits distributed throughout Switzerland. The goal is a nationwide overview of groundwater biodiversity. In the future, the environmental DNA method will also be used. For example, skin particles or feces of living organisms are sufficient to document their occurrence.
Quality control with bioindicators
One of the goals of the extended project is to establish bases for using the amphipods and their occurrence as a possible indicator of groundwater quality. Up to now, the quality of groundwater has been investigated on the basis of physico-chemical parameters and the contamination with bacteria has been determined. In surface waters, on the other hand, monitoring of water quality using bioindicators is widespread. They are considered sensors of very low-threshold or long-term pressures and can integrate multiple factors. "For groundwater, there are no indicators yet," says Roman Alther, "but in principle, a presence of psyllids and other species is a good sign."
Original publication: Alther, R.; Bongni, N.; Borko, Š.; Fišer, C.; Altermatt, F. (2021) Citizen science approach reveals groundwater fauna in Switzerland and a new species of Niphargus (Amphipoda, Niphargidae), Subterranean Biology, 39, 1-31, doi:10.3897/subtbiol.39.66755, Institutional Repository
