Between darkness and light: spring habitats provide new perspectives for modern researchers on groundwater biology

Springs are interfaces between groundwater and surface habitats and may play an important role in the study of subterranean animals. In this systematic evidence review and meta-analysis, we explore whether observations of stygobionts in springs are relevant and more common than observations of epigean animals in groundwater. We searched the Web of Science database for papers on groundwater fauna and spring fauna. For each paper we found, we recorded whether the paper reported the occurrence of typical stygobionts in springs, of surface animals in groundwater, or of the same taxa in both habitats. If so, we recorded how many such species were reported. We also recorded the scientific discipline of each study and the year of publication. Our search yielded 342 papers. A considerable number of these papers reported stygobionts in springs: 20% of papers dealing with groundwater fauna and 16% of papers dealing with spring fauna reported the occurrence of stygobionts in spring habitats. Both the number of papers that mentioned stygobionts in springs, and the number of stygobiont species that were documented in springs, were higher than equivalent measures for the occurrence of surface fauna underground. We also detected a positive relationship between year of publication and the number of reports of stygofauna in springs. To broaden the insights from biological research on underground environments, we suggest that springs should be considered not only as simple sampling points of stygobionts but also as core stygobiont habitats.

Groundwater fauna in an urban area – natural or affected?

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.

Citizen science approach reveals groundwater fauna in Switzerland and a new species of Niphargus (Amphipoda, Niphargidae)

Knowledge on the diversity and distribution of subterranean organisms is still scattered, even in faunistically relatively well-researched countries such as Switzerland. This is mostly due to the restricted access to these subterranean habitats. Better knowledge on these organisms is needed, because they contribute substantially to overall biodiversity of a region, often contain unique elements of biodiversity, and can potentially be indicative of the ecological status of subterranean ecosystems that are providing important ecosystem services such as drinking water. Past research on subterranean organisms has often used highly specialised sampling techniques and expert knowledge. Here, we show that inclusion of non-professionals can be an alternative and highly promising sampling strategy. We retrieved citizen science-based samples from municipal groundwater wells across Switzerland, mainly from the Swiss Plateau. Opportunistic samples from 313 sites revealed a previously undocumented groundwater fauna including organisms from different major invertebrate groups, with a dominance of crustaceans. Here, we studied amphipods of the genus Niphargus. Among all 363 individuals sampled, we found in total eight nominal species. Two of them, namely N. fontanus and N. kieferi, are reported for Switzerland for the first time. We also found four further phylogenetic lineages that are potentially new species to science. One of them is here formally described as Niphargus arolaensissp. nov. The description is based on molecular and morphometric data. Our study proves the suitability of citizen science to document subterranean diversity, supports groundwater conservation efforts with data, and raises awareness for the relevance and biodiversity of groundwater amphipods among stakeholders.

Using environmental DNA methods to survey for rare groundwater fauna: Detection of an endangered endemic cave crayfish in northern Alabama

The conservation and management of subterranean biodiversity is hindered by a lack of knowledge on the true distributions for many species, e.g., the Wallacean shortfall. In recent years, several studies have demonstrated the potential of environmental DNA (eDNA) as an effective approach to detect and monitor biodiversity, including rare, threatened, and endangered taxa. However, there are few eDNA studies of groundwater fauna. Here we report the results of the development and implementation of an eDNA assay targeting a short fragment of the mitochondrial CO1 locus of a critically imperiled cave crayfish, the Sweet Home Alabama Cave Crayfish (Cambarus speleocoopi), known from just four cave systems in the Interior Plateau karst region of northern Alabama. We detected C. speleocoopi DNA from water samples collected at 5 of 16 sites sampled (caves and springs), including two historical sites as well as three additional and potentially new sites in Marshall County, Alabama. All three of these sites were within 2 km of historical sites. Our study is the first to detect a groundwater crustacean in the Interior Plateau karst region. Additionally, our study contributes to the growing literature that eDNA is a viable complementary tool for detection and monitoring of a fauna that is difficult to survey and study using traditional approaches.

Groundwater fauna in an urban area: natural or affected?

In Germany 70 % of the drinking water demand is met by groundwater, whose quality is the product of manifold physical-chemical and biological cleaning processes. As healthy groundwater ecosystems help to provide clean drinking water, it is necessary to assess the ecological conditions of these ecosystems. This is particularly true for densely populated, urban areas, where faunistic groundwater investigations are still scare. The aim of this study is therefore to provide a first-tier assessment of the groundwater fauna in an urban area. Thus, we assess the ecological condition of an anthropogenically influenced aquifer by analysing the groundwater fauna in 39 groundwater monitoring wells in Karlsruhe (Germany) and a nearby forest land. For classification we apply the scheme from the Federal Environmental Agency (UBA), in which a threshold of more than 70 % of Crustaceans and of less than 20 % of Oligochaetes serves as an indication for good ecological conditions. In our study 35 % of the wells in the urban area fulfil these criteria, and even in the pristine forest land only 50 % of the wells indicate fine ecological conditions. While the assessment reveals that ecological conditions in the studied urban area are predominantly not in a good ecological state, there is no clear spatial pattern with respect to land use and anthropogenic impacts. However, there are noticeable differences in the spatial distribution of species and abiotic groundwater characteristics between wells in forest land and the urban area, which indicates that more comprehensive assessment methods are required to fully capture the different effects on groundwater fauna.

Is groundwater fauna impacted by swine effluent fertigation?

Neste estudo, testamos uma fertirrigação de efluente suíno que afeta a fauna aquática subterrânea do aqüífero livre poroso. Os parâmetros químicos e químicos das águas subterrâneas foram determinados e correlacionados com a fauna que não apresentam fator aquático em áreas fertigadas e não fertigadas com efluentes que não são biodigestores. Como influências da sazonalidade na qualidade da água também foram testadas. Para esse fim, como águas subterrâneas de poços de água e piezômetros preexistentes de propriedade de agricultores, usando o ventilador e a rede de malha de 65 micra para filtrar os organismos. Os resultados físicos e químicos podem mostrar algumas alterações nos parâmetros de qualidade.Registramos doze táxons de invertebrados, sendo Acari e Copepoda os mais prevalentes. A colonização de espécies aquáticas pode ter sido limitada pelo surgimento de organismos exóticos e pela qualidade da água.

Biodiversity and distribution of groundwater fauna in the Oum-El-Bouaghi region (Northeast of Algeria)

Hichem K, Ramzi H, Djemoi M. 2019. Biodiversity and distribution of groundwater fauna in the Oum-El-Bouaghi region (Northeast of Algeria). Biodiversitas 20: 3553-3558. This study concerns the aquatic fauna of wells and springs in north of the city of Oum El Bouaghi, in the western part of the Tamlouka plain, north-eastern Algeria. 16 wells and two springs were selected and a seasonal sampling of the aquatic fauna was carried out from September 2017 to May 2018, covering periods of high and low water. Two types of traps were used: the phreatobiological net and baited traps. The composition of fauna was found to be 26 taxa and 6617 individuals, dominated by Crustaceans 47% followed by insects and shellfish 23% for each. Only one stygoby species was collected mainly: Pseudoniphargus djemoi.