Research Article |
Corresponding author: Roman Alther ( roman.alther@eawag.ch ) Academic editor: Traian Brad
© 2021 Roman Alther, Nicole Bongni, Špela Borko, Cene Fišer, Florian Altermatt.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
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. https://doi.org/10.3897/subtbiol.39.66755
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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 arolaensis sp. 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.
Biodiversity, conservation, monitoring, species description, stygofauna, taxonomy
Groundwater is among the most essential resources for human well-being (
For many regions of the world the knowledge about the diversity and distribution of groundwater organisms – or subterranean organisms in general – is mostly lacking (
A key part of groundwater diversity is composed by invertebrates, of which crustaceans, and especially amphipods, are among the most common ones (
Here we addressed this knowledge gap on groundwater organisms, with a focus on the genus Niphargus
We focused on the Swiss plateau, a region where only very little previous data on groundwater amphipods were available (
The study area (Switzerland) with the four focus cantons highlighted in grey. The map shows all sites sampled within the current citizen science project in which Niphargus sp. were either found (red circles) or not found (grey circles). All previously known findings of Niphargus sp. from Switzerland are indicated as orange circles. Geodata from Federal Office of Topography.
The sampling of groundwater wells by the well managers followed a predefined protocol, fostering comparability. We sent the sampling material, instructions, and data sheets (Fig.
A Sampling material, instructions, and data sheets that were provided to well managers B the filter bags were fixed to groundwater draining pipes and collected all washed organisms larger than 0.8 mm C the overflow chambers were sampled with a small aquarium net (here: type locality of Niphargus arolaensis sp. nov.).
After receiving back the samples, we separated all amphipods from organic matter and other macroinvertebrates, using a sorting plate and a stereomicroscope (Nikon SMZ1500, 0.75–11.25×). We identified the Niphargus specimens to species level with a stereomicroscope (Olympus SZX9) and a light microscope (Zeiss Primo Star). For detailed analysis, we dissected a few specimens in glycerol, and mounted them on glass slides in glycerol gelatine. We performed morphometric measurements using the program cellSense (Olympus) according to the landmarks detailed in
For Niphargus specimens, we sequenced from each site at least one specimen of each morphologically distinct Niphargus species, resulting in 120 specimens from 68 sites. We isolated genomic DNA from one of the pereopods using the GenElute Mammalian Genomic DNA (Sigma-Aldrich, United States). We amplified the two nuclear DNA gene fragments: part of 28S rRNA gene (28S), histone H3 (H3) and the mitochondrial cytochrome oxidase I (COI) gene. We used primers from
We aligned the sequences with MAFFT 7.388 (
We ran molecular phylogenetic analyses to assess the phylogenetic position of new Niphargus species within the genus. The dataset comprised six specimens of newly described species and 163 Niphargus taxa from different phylogenetic lineages with emphasis on potentially closely related species, each represented by one specimen. We used Microniphargus leruthi Schellenberg, 1934 and two species from genus Pseudoniphargus Chevreux, 1901 as an outgroup. We used available sequences from previous studies (
We reconstructed the phylogenetic relationships with Bayesian inference (BA) in MrBayes v3.2.6 (
Our citizen science approach proofed successful and had high return rates. First response rate to an initial letter asking for participation was 21% (40 out of the 191 contacted well managers). Subsequent talking to the well managers in person at the annual meeting resulted in more than two thirds of positive feedback. Some of the participants that initially received the letter volunteered only after meeting in person. We sent the sampling kit (Fig.
The well managers provided either samples or information about null findings. Many well managers sampled multiple sites, resulting in 313 unique sites sampled (pipes draining different aquifers but collected in the same water well were considered separate sites). Additionally, some sites were sampled repeatedly, resulting in 491 samples that were sent back to our lab. 56% (274) of the samples contained organisms, totalling to over 1,900 specimens. The samples contained overall 18 different orders of macroinvertebrates. These were: Amphipoda (Crustacea, Malacostraca), Araneae (Arachnida), Chordeumatida (Diplopoda), Coleoptera (Insecta), Diptera (Insecta), Entomobryomorpha (Entognatha, Collembola), Ephemeroptera (Insecta), Hemiptera (Insecta), Hymenoptera (Insecta), Isopoda (Crustacea, Malacostraca), Julida (Diplopoda), Littorinimorpha (Gastropoda), Plecoptera (Insecta), Poduromorpha (Entognatha, Collembola), Polydesmida (Diplopoda), Pseudoscorpiones (Arachnida), Opiliones (Arachnida), and Trichoptera (Insecta). Some of these organisms were not groundwater inhabitants, but may have been washed in from surface waters, or even of terrestrial origin. Amphipods were the most common and most widespread groundwater organisms in the samples, with in total 424 individuals collected from 74 sites. The majority of those (363 individuals from 63 sites) belonged to the genus Niphargus, while the remaining were epigean Gammarus fossarum that either had been washed from surface waters or colonised the water-wells from downstream sites. Here, we only focus on Niphargus species.
Species identity determination using the COI fragment and subsequent alignment to existing barcodes revealed 13 different phylogenetic lineages of Niphargus. Nine of them could be ascribed to eight nominal species. These were: Niphargus auerbachi Schellenberg 1934, Niphargus fontanus Spence Bate, 1859 (belonging to the clade A sensu
Maps depicting all Niphargus sp. findings and their respective taxonomic assignment from the current citizen science project (red circles) as well as all previously known findings of the respective species (orange circles). One species is new to science (A) and two species are reported for the first time for Switzerland (C, D). Six species (B, E–I) were previously reported from Switzerland. Map G shows all cryptic N. rhenorhodanensis species, including the newly found specimen of lineage H in red. Geodata from Federal Office of Topography.
Six of the found Niphargus species had been previously reported from Switzerland (Fig.
Two species are herewith reported from Switzerland for the first time, namely Niphargus fontanus and Niphargus kieferi. We found N. fontanus in 19 sites in the Aare drainage area and the Rhine drainage area (Fig.
Twenty-five specimens sampled from three water wells in the cantons of Aargau and Bern, all in the Aare drainage area (Fig.
Both newly constructed phylogenetic trees showed a congruent topology. Swiss amphipods classify into few well-defined lineages. The relationship between these lineages is incompletely resolved. While ML recovered a relatively well supported clade that comprised most species reported from Switzerland (Fig.
We submitted all newly generated COI sequences of Niphargus species to GenBank. All accession numbers are listed in Suppl. material
Holotype
(Figs
A new Niphargus species from Switzerland. Niphargus arolaensis sp. nov. (holotype, female 7.8 mm). The two diagnostic features (seven comb-like spiniform setae on the outer lobe of maxilla I and two spiniform setae on the lower distal part of the first urosomite near the insertion of uropod 1) are highlighted on the figure.
Paratypes : One male and three females of respective lengths 7.7, 7.8, 8.7 and 9.5 mm; specimens are partially dissected and mounted on slides with voucher numbers GBIFCH00602903, GBIFCH00602904, GBIFCH00602905, GBIFCH00602906, GBIFCH00602907.
Stedliquelle (left inflow), Aarberg, Switzerland. CH1903: 588'518, 209'959 (WGS84: 47.04056°N, 7.28756°E), 478 m a.s.l.
Only known from three drinking water wells: Stedtliquelle close to Aarberg, Stöckhof close to Egliswil and Lätzloch close to Kölliken, all in Switzerland.
The name “arolaensis” is derived from the Latin name of the river Aare (Arola), since all findings were located in the drainage basin of the river Aare.
Small and slender Niphargus, defined by combination of two traits. Two spiniform setae are located on the lower distal part of the first urosomite near the insertion of uropod I (Fig.
Head and trunk
(Fig.
Pleonites I–III with up to three setae along the entire dorso-posterior margins. Epimeral plate II roughly perpendicular, posterior and ventral margins convex; ventro-postero-distal corner distinct; along ventral and posterior margins three spiniform and four to five thin setae, respectively. Epimeral plate III inclined, posterior and ventral margin slightly-distinctly concave and slightly convex, respectively; ventro-postero-distal corner distinct but not produced. Along ventral and posterior margin 3–4 spiniform seta; along posterior margin five thin setae.
Urosomite I postero-dorso-laterally with one slender, flexible seta; urosomite II postero-dorso-laterally with 2–3 strong setae among which at least one is strong and stout; urosomite III without seta. Ventrally on urosomite I, at the base of uropod I, are two strong spiniform setae in a row.
Telson (Fig.
Antennae
(Fig.
Ratio of lengths antenna I : antenna II as 1 : [0.48–0.52]. Flagellum of antenna II (B) with 7–8 articles; each article with setae and elongated, thick sensilla of unknown function. Peduncle articles lengths 4 : 5 in ratio 1 : [0.89–0.95]; flagellum 0.57–0.66 of length of peduncle articles 4+5.
Mouthparts
(Fig.
Left mandible (C and D): incisor with five teeth, lacinia mobilis with four teeth; between lacinia and molar a row of serrated setae, molar triturative, at the base of molar long seta. Right mandible (E and F): incisor processus with four teeth, lacinia mobilis with several small teeth, between lacinia and molar a row of thick serrated setae, molar triturative. Mandibular palp article 3 articulated. Ratio of mandibular palp article 2 (middle) : article 3 (distal) is 1 : [1.2–1.37]. Proximal palp article without setae; the middle article with 7–8 setae; distal article with 3–5 A setae in a row; 3–4 B setae; 15–18 D setae and four E setae.
Maxilla I (G and H), distal palp article with 6–7 apical setae. Outer lobe of maxilla I with a row of 7 stout spiniform setae, each with many (>4) denticles (comb-like); inner lobe with two setae along medial and apical margin.
Maxilla II (I and K) inner lobe slightly smaller than outer lobe; both lobes setose apically and medially.
Maxilliped (L) inner lobe with three stout flattened and tooth-like setae apically and 6–11 setae along latero-apical margins; outer lobe with 7–11 stout and flattened, tooth-like setae mesially-subapically and 5–7 thick rounded and hairy setae apically. Maxilliped palp article 2 with 8–10 rows of setae along inner margin; dactylus with a dorsal seta, and few tiny setae at the socket.
Coxal plates, and gills
(Figs
Gnathopod I
(Fig.
Gnathopod II
(Fig.
Pereopods III–IV
(Fig.
Pereopods V–VII
(Fig.
Bases V–VII slender, respective length : width ratios as 1 : [0.57–0.64], 1 : [0.57–0.64] and 1 : [0.58–0.64]; posterior margins straight or slightly convex, distally ending with small to moderate-sized lobes; posterior margins armed with 8–10, 9–10 and 8–10 setae, respectively; anterior margins armed with 6–7, 6–7 and 5–6 groups of stouter setae, respectively. Dactyli V–VII with one dorsal plumose seta; at the base of nail one tiny setae and one spiniform seta. Dactylus VII long and slender, its length measures 0.28–0.32 of propodus length; nail long, measuring 0.34–0.38 of total dactylus length.
Pleopods and uropods
(Fig.
Uropod I (B) protopodite with six dorso-lateral spiniform setae and 2–3 dorso-medial spiniform setae. The ratio exopodite : endopodite lengths is 1 : [0.98–1.06]; rami straight. Endopodite with four individual spiniform setae laterally, rarely accompanied with a slender and flexible seta, and four spiniform setae apically. Exopodite with 2–6 spiniform setae alone or in groups; apically 4–6 spiniform setae.
Uropod II (C) exopodite : endopodite lengths ratio is 1 : [1.00–1.05].
Uropod III (D) rod-shaped, measuring 0.20–0.22 of body length. Protopodite elongated, sometimes with a single weak lateral seta and with 5–7 apical spiniform setae. Endopodite short, measures approximately 0.56–0.63 of protopodite length; laterally armed with 0–1 spiniform setae, apically armed with 3–4 spiniform setae, of which 1–2 are strong and spiniform. Exopodite of uropod III rod-shaped, distal article 0.16–0.22 of the proximal article length. Proximal article with five groups of spiniform and plumose setae along inner margin and 4–5 groups of spiniform setae along outer margin. Distal article with 0–2 setae laterally and 1–4 setae apically.
We found no sexual dimorphism in proportions, females had oostegites on pereopods II–IV. Number of setae vary, smaller specimens had fewer setae.
The diagnosis is a combination two unambiguous traits. Two strong spiniform setae at the base of uropod I is a rare character, hitherto found only in Niphargus bodoni G. Karaman, 1985 (Italy,
Unlike for the Swiss cave fauna (
The collaboration with well managers significantly increased the current knowledge about Swiss Niphargus species, raising the number of known sites of Niphargus occurrence by about 22% (288, compared to 45 in Altermatt et al. 2013 and 225 in
The most spectacular finding of this citizen science project was the finding of a species new to science, here formally described as N. arolaensis sp. nov. (Figs
While the adjacent mountainous regions (Jura Mountains and Alps) have been more intensely studied with respect to subterranean amphipods, these studies almost exclusively focussed on karstic regions (especially caves) or on interstitial habitats and less on inaccessible alluvial aquifers. Cave habitats are almost absent in the Swiss Plateau and many interstitial habitats, especially of the larger rivers, have been heavily modified by humans by river regulations and dams. Our study now shows that the groundwater habitats in the Swiss Plateau, geologically largely dominated by alluvial habitats shaped by glaciers, is (next to karstic caves and interstitial) another important habitat of Niphargus in Switzerland, encompassing a surprisingly high diversity of Niphargus species.
Swiss amphipods classify into few well-defined clades with different phylogenetic origin within Niphargus (Fig.
Next to Niphargus arolaensis sp. nov., we also report two additional species new to the Swiss fauna. The first one belongs to the Niphargus fontanus species complex, originally described from the United Kingdom, but also found in continental Europe. Its lineages may not be told apart based on morphology alone, and formal revision of the complex is pending. Our specimens found belong to the lineage N. fontanus A, that was reported from France, Belgium, Germany and parts of Austria (
The second species reported for the first time for Switzerland is Niphargus kieferi (Fig.
We also increased the knowledge on the distribution of six Niphargus species hitherto already known from Switzerland, mostly for the Swiss Plateau, but also beyond. Specifically, for the recently described species N. luchoffmanni (Fig.
Altogether, our study reveals that the Niphargus fauna of Switzerland has distinct patterns of biodiversity and distribution. A community of species inhabiting karstic areas (especially caves) is predominantly found in the Jura mountains in (North)Western Switzerland (N. puteanus, N. rhenorhodanensis, but also N. virei). Another community of species is predominantly inhabiting the Northern (pre)Alps, in a wide range of habitats such as caves, interstitial and groundwater, including N. luchoffmanni, N. muotae, N. murimali, N. styx, and N. thienemanni. Geographically in between, in the Swiss Plateau, we now report a third community cluster of species predominantly inhabiting interstitial and (alluvial) groundwater habitats, including N. auerbachi, N. fontanus, N. kieferi, and N. tonywhitteni. Further research is needed especially in the Southern and Western part of Switzerland, especially those falling into the Rhone, Ticino and Adda drainage basins.
Next to the increase in faunistic knowledge on amphipods in Switzerland, our study also showed how a generalizable citizen science approach targeting well managers could be exceptionally fruitful for gaining access to an otherwise hardly accessible ecosystem. There are debates what qualifies to be considered a citizen science project (
Overall, our approach proved highly successful. However, there are still some possible limitations associated to the approach and methods chosen. Since the groundwater was sampled in a passive way and not pumped, most retrieved samples were in a good state. However, the collected organisms may not be representative of the overall diversity in the respective localities, since some types of organisms might get washed out more easily than others. The discharge differed considerably between the sampled localities and could change depending on the surface conditions (personal communication by the well managers). Additionally, only organisms bigger than 0.8 mm were collected due to the chosen mesh size. All these circumstances make the approach a rather qualitative assessment, likely to underestimate the true diversity of groundwater fauna, highlighting the need of further and more intense sampling. This should not only cover different seasons, but all biogeographic regions of Switzerland. The herein described citizen science approach offers the potential of sampling an extended timescale and to capture potential seasonal patterns (
Our study showed the feasibility of a citizen science approach in collecting data on groundwater fauna on a large spatial scale. This concept hasn’t been applied at this extent to study groundwater fauna. Collaboration with local well managers resulted in groundwater samples from 313 sites, mainly across the Swiss Plateau. They included different major invertebrate groups, mainly crustaceans. We focused on the genus Niphargus, with 363 individuals the most common taxa in the available samples. We report eight nominal species (N. auerbachi, N. luchoffmanni, N. puteanus, N. rhenorhodanensis, N. thienemanni, N. tonywhitteni, N. fontanus and N. kieferi), with the latter two being reported for Switzerland for the first time. Additionally, we discovered four phylogenetic lineages that are potentially new species to science. One of them we describe as Niphargus arolaensis sp. nov. Our study is a proof-of-concept, showing that a citizen science approach could increase spatial coverage substantially, but could also raise awareness about groundwater biodiversity among stakeholders.
We would like to thank all the drinking water well managers that participated in our study and showed much enthusiasm and interest. We acknowledge the help of the Brunnenmeisterverband in fostering interest in the project. Many thanks to Olaf Rodrigues, who did some initial testing on the feasibility of the approach. Helpful suggestions and comments by Fabio Stoch greatly improved the manuscript. The project is funded by the Swiss Federal Office for the Environment FOEN/BAFU (project “AmphiWell” to FA and RA), the Swiss National Science Foundation (grant nr. PP00P3_150698 to FA), the Slovenian Research Agency, Program P1-084, Project J1-2464 (to CF), and a PhD grant to Špela Borko (contract no. KB139382597).
Figure S1
Data type: image (.tiff file)
Explanation note: MrBayes: Phylogenetic hypothesis from Bayesian inference. Nodes are labelled with posterior probabilities, when higher than 0.80. Lower values are reported in light-grey for focal Swiss clade. Species that occur in Switzerland are in bold.
Supporting file 1
Data type: pdf document
Explanation note: Standardized information letter to well managers, in German.
Supporting file 2
Data type: pdf document
Explanation note: Sampling instructions to well managers, in German.
Supporting file 3
Data type: pdf document
Explanation note: Sampling instructions to well managers, in French.
Supporting file 4
Data type: pdf document
Explanation note: Sampling protocol to well managers, in German.
Supporting file 5
Data type: pdf document
Explanation note: Sampling protocol to well managers, in French.
Supporting file 6
Data type: pdf document
Explanation note: Sampling labels to well managers, in German.
Supporting file 7
Data type: pdf document
Explanation note: Sampling labels to well managers, in French.
Table S1 (Revised)
Data type: excel table
Explanation note: List of species used for phylogenetic analyses, with the origin of samples, and GenBank accession numbers.
New corrected file uploaded on 3 February 2022.
Table S2
Data type: excel table
Explanation note: List of discovered Niphargus individuals from the citizen science approach with GenBank accession numbers.
Table S3
Data type: table (docx. file)
Explanation note: Results of substitution model selection for Bayesian inference (Partition Finder 2) and maximum likelihood (IQ-TREE) analyses.