•Microsatellite markers for five surface and groundwater species.•Populations of surface and groundwater species are highly variable and structured.•Neighboring populations share low levels of gene ...flow.•Genetic methods reveal hidden natural or man-made groundwater hydrological patterns.•The StygotracingⓇapproach represents a promising tool for drinking water management.
Groundwater is one of our most important resources, however groundwater ecosystems are among the most understudied habitats of the planet earth. Studies on groundwater organisms are hampered by the difficult accessibility of species, the lack of morphological differentiation and the limitation for laboratory cultures. One important approach to overcome these shortcomings is to provide sensitive genetic methods to unravel patterns of biodiversity, population structure and gene flow in natural populations. In this study we present five sets of microsatellite markers developed for the isopods Asellus aquaticus and Proasellus slavus, the cyclopoides Paracyclops fimbriatus and Acanthocyclops sensitivus and the harpacticoide Bryocamptus echinatus (Crustacea). Two of these species were subjected to detailed population genetic analyses: We studied 501 specimens of Asellus aquaticus from four different regions in Northern Germany using nine microsatellite markers and 70 specimens of Bryocamptus echinatus using nine microsatellite markers from three different sampling sites in South-Western Germany. Our results show that genetic diversity is high (A. aquaticus: 10 to 20 and B. echinatus: 4 to 18 alleles per locus) among populations of aquatic invertebrates, populations are highly differentiated (FST > 0.2) and genetic differentiation was associated with geographic patterns. Applications of molecular genetic methods and their use for the detection of hydrological exchange processes relevant for drinking water suppliers are demonstrated and discussed.
Although groundwater is a highly fragmented habitat, both faunistic and hydraulic interactions exist between different aquifers and between groundwater and surface water.
For the drinking water ...suppliers, in particular surface water intrusion into groundwater means an increased risk of contamination. Thus risk assessment is essential for quality assurance in drinking water supply. In this context, several questions arise: 1) Where does the water come from?; 2) Are there any hydraulic shortcuts to surface waters?; 3) Are there any hydrological interactions between different aquifers?; 4) What are the catchment borders?
Invertebrate fauna may display the strength and the direction of hydrological interactions since the dispersal is linked to hydrological pathways. Our hypothesis is: The more intense the hydrogeological interactions the closer the relationship between individuals and populations.
The degree of relationship can be determined using a kind of paternity test for invertebrates. This is a population genetic, microsatellite-based method called StygoTracing. The most important tools of StygoTracing are the primers, which have to be designed for each individual tracer species.
Good tracer species are those, which have a wide distribution and occur with high frequency and are easy to determine. We have chosen three species both stygo- and non-stygobiotic ones. The primers and microsatellite analysis applied proved to be suitable even to distinguish single individuals from each other.
StygoTracing has been successfully tested for water supply systems, but not yet in the field.
Thus seven pilot areas were selected in Bavaria, Baden-Württemberg, Palatinate and Saxony, and sampling was conducted on a total of 186 groundwater, spring and stream sites. Meanwhile, first genetic data are available and initial evaluations reveal plausible correlations on different spatial scales.
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