Groundwater fauna in an urban area – natural or affected?

Abstract

Abstract. In Germany, 70 % of the drinking water demand is met by groundwater, for which the quality is the product of multiple physical–chemical and biological processes. As healthy groundwater ecosystems help to provide clean drinking water, it is necessary to assess their ecological conditions. This is particularly true for densely populated urban areas, where faunistic groundwater investigations are still scarce. The aim of this study is, therefore, to provide a first assessment of the groundwater fauna in an urban area. Thus, we examine the ecological status of an anthropogenically influenced aquifer by analysing fauna in 39 groundwater monitoring wells in the city of Karlsruhe (Germany). For classification, we apply the groundwater ecosystem status index (GESI), in which a threshold of more than 70 % of crustaceans and less than 20 % of oligochaetes serves as an indication for very good and good ecological conditions. Our study reveals that only 35 % of the wells in the residential, commercial and industrial areas and 50 % of wells in the forested area fulfil these criteria. However, the study did not find clear spatial patterns with respect to land use and other anthropogenic impacts, in particular with respect to groundwater temperature. Nevertheless, there are noticeable differences in the spatial distribution of species in combination with abiotic groundwater characteristics in groundwater of the different areas of the city, which indicate that a more comprehensive assessment is required to evaluate the groundwater ecological status in more detail. In particular, more indicators, such as groundwater temperature, indicator species, delineation of site-specific characteristics and natural reference conditions should be considered.

Global overview on groundwater fauna

“…The development of this ‘Groundwater Health Index’ (GHI) framework was triggered by Australian water management policies and the heavy reliance on groundwater from irrigation‐based industries. Methods to measure groundwater health and monitor groundwater ecosystems continue to be refined and developed (di Lorenzo, Fiasca, di Camillo, et al, 2020; Fillinger et al, 2019; Griebler, Stein, et al, 2014; Koch et al, 2021; Korbel & Hose, 2017), with these management tools being used by governments to monitor groundwater health (e.g. report Korbel, Greenfield, & Hose, 2022).…”

Wicked facets of the German energy transition – examples from the electricity, heating, transport, and industry sectors

“…Lower system efficiencies are associated with higher operating costs and possibly the need for fossil auxiliary technologies such as gas boilers or compression chillers (Miglani, Orehounig, and Carmeliet 2018;Tissen et al 2019). Besides technical drawbacks, shallow geothermal utilisation may entail other trade-offs, including environmental aspects such as detrimental changes to the groundwater ecosystem and loss of the respective ecosystem services (Blum et al 2021;Griebler and Avramov 2015;Koch et al 2021). Conflicts of use of shallow groundwater and decreasing profitability of regional supply companies, which often base their business model on the profitable gas supply, might also arise from an increasing spread of this technology.…”

“…This information deficit is also reflected in legislation. While there is a variety of individual laws and regulations in Germany regarding the protection of groundwater as a resource, the legislation (including the Federal Water Act and Federal groundwater regulation as well as the Federal Nature Conservation Act,) does not consider groundwater protection at an ecosystem-level perspective (Hahn, Schweer, and Griebler 2018;Koch et al 2021).…”

Groundwater environmental DNA metabarcoding reveals hidden diversity and reflects land‐use and geology

“…The latter (and particularly amphipods) are commonly used as bioindicators in monitoring surface or groundwater ecosystems (e.g. Koch et al, 2021). Studying these organisms, however, is a major challenge, because most subterranean voids are not or very poorly accessible to humans, and much of the groundwater fauna is insufficiently known from a taxonomic perspective.…”