Peer Review #2 of "Between darkness and light: spring habitats provide new perspectives for modern researchers on groundwater biology (v0.2) (original) (raw)
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A comparison of stygofauna communities inside and outside groundwater bores
Limnologica - Ecology and Management of Inland Waters, 2005
Sampling stygofauna is both time consuming and labour intensive. The challenge is to get samples from as many bores as possible within a limited time. The essential assumption for this is that faunal communities inside bores are comparable and representative of the communities outside. To compare relative abundance, taxonomic richness and community composition of the fauna inside groundwater bores to the fauna of the surrounding aquifer, 20 monitoring bores in Palatinate, southwestern Germany, were sampled twice in 1 month. Initially, a sample of 4 l of water was collected from the bottom of each bore. A further sample of 51 l was collected from the groundwater surrounding the bore using a pneumatic piston pump with double packer sampler. Water chemistry inside and outside the bore was similar, but the relative amounts of sediments within the bores were higher compared to those from outside. Relative abundances of fauna inside the bores were higher than in the aquifer, but taxonomic composition was similar with the exception of the proportions of nematodes and amphipods, which were higher inside. As a result, the proportions of cyclopoids were lower inside. Higher nematode proportions are explained partially by the nearly complete extraction of bore sediment. A ''habitat heterogeneity effect'' states that in heterogeneous aquifers with few suitable habitats, faunal distribution is supposed to be extremely patchy. Thus, detritus accumulates in bores, attracting animals and providing ''habitat islands'' in the groundwater. This effect could explain the higher amphipode proportions inside the bores, which were generally more frequently populated than the surrounding groundwater. As a consequence, fauna is thought to be nearly absent from groundwater, where suitable habitats are lacking. In those sparsely populated aquifers, samples representative of the aquifer taxonomic richness and composition can only be collected by removing large volumes of water, or by sampling the bottom of bores. These findings also suggest that the use of unbaited colonisation chambers or traps in the groundwater, which are comparable with bores, would seem to be a promising approach.
Quarterly Journal of Engineering Geology and Hydrogeology, 2009
The invertebrate ecology of aquifers has received little attention. This paper presents an analysis of stygobite (obligate groundwater) fauna from Great Britain (England, Scotland and Wales). A review is presented of the ecosystem functions performed by these creatures, their potential vulnerability to anthropogenic stress including water pollution and abstraction, and research priorities that will allow current groundwater management challenges to be addressed. In Great Britain stygobites are largely restricted to England and Wales. The assemblage comprises crustacean invertebrates (nine species) and is very limited in comparison with continental Europe. There is only one known endemic species in Great Britain, Niphargus glenniei (a further two endemic crustaceans are also known from the Republic of Ireland). Additionally, a suite of water mites (18 species) is found in the interstitial habitats of running waters in Great Britain. Niphargus glenniei was recently added to the United Kingdom Biodiversity Action Plan priority species list. Stygobites, which are found only in subterranean environments such as aquifers, springs and the hyporheic zone of rivers, make a unique contribution to biodiversity. Our analysis suggests that both the glacial legacy and the nature of the (hydro)geology are major controls on the distribution of these assemblages. Most records were from locations to the south of the southern limit of the ice sheet during the Devensian glaciation. The majority of stygobites were also found in calcareous strata, although high calcium carbonate concentrations may not be important to all crustacean stygobites. Records were dominated by samples from the Chalk, the Carboniferous and Jurassic Limestone aquifers, and from other strongly fissured strata. Strata with extensive fissuring may provide the greatest availability of habitat for groundwater fauna. Our investigation revealed that there are relatively few sites from which stygobites have been recorded in Great Britain (513 sites at which records of stygobites have been confirmed). Research is needed to improve our understanding of the basic biology and ecology of groundwater-dwelling fauna and the range of ecosystem services that they provide. An understanding of the response of groundwater fauna to stress caused by pollution and abstraction pressures is also needed, together with the development of appropriate monitoring, assessment and protection criteria. The Water Framework Directive requires a more integrated assessment of the chemical, water resources and ecological conditions of water bodies. Stygobites have the potential to act as sentinels in the subterranean environment and help inform us about the condition and ecological health of this little-considered habitat.
Hydrobiologia, 2017
At regional and catchment scales, geology and hydrogeology strongly influence the distribution of groundwater invertebrates (stygofauna), but the fine scale distribution of stygofauna in sedimentary aquifers remains poorly studied. In this study, we examine the small-scale distribution of stygofauna in sediments of a perched aquifer in an upland swamp in south eastern Australia. We installed a series of piezometers which accessed either the full sediment profile or one of four discrete sedimentary layers in the swamp. Piezometers were sampled for stygofauna and 2H and 18O isotopes in the groundwater. The swamp contained a taxonomically diverse and abundant stygofauna, which was distributed throughout the swamp and similar in composition to that of other aquifers in the region. There were strong temporal changes in the faunal assemblages but the stimuli for these changes remain unknown. Isotope analysis indicated that the swamp water was well mixed despite localised inputs of groundwater from springs. Accordingly, we could not explore the relative influence of groundwater inputs on fauna; however, we have shown clearly that stygofauna were strongly influenced by sediment properties, with the abundance of stygofauna in the dense, fine sandy sediments being significantly lower than in the coarser sedimentary layers above and below.
ARPHA Conference Abstracts
The potential of subterranean environments as models to address major evolutionary and ecological questions has been highlighted in the literature. They represent partially isolated, discrete units offering several replicates of the same evolutionary processes. Species occurrence data of these environments is abundant, although sparse in the literature or gathered in databases established according to regional, taxonomical, or ecological criteria. We here present a newly assembled dataset consisting of records of aquatic animals in all types of caves or wells from all over the world. Literature sources were gathered from Google Scholar by independently searching for each metazoan phylum/arthropod order, as well as the key words “cave”, “groundwater”, “well”, or “stygobite”, in English, Galician, Spanish, Portuguese, Catalonian, French, Italian, Hungarian, Greek, German, Polish, Russian, and Serbo-Croatian. The relevance of each source was confirmed after checking the title and the a...
Journal of Limnology, 2016
The fauna in the hyporheic zones of rivers has been relatively well studied but that from the phreatic zone remains comparatively unknown and there are few investigations into deeper intergranular aquifers (over 30 m in depth) due to technical difficulties. Two shallow boreholes of 29 m depth and two deep boreholes of 100 m depth, both near Ljubljana (Slovenia), were sampled more than 30 times between 14 January 2008 and 3 March 2009. On each occasion 14.4 to 18.0 m 3 of water were abstracted using a high-capacity pump, then filtered by means of a plankton net with a mesh size of 60 µm. Organisms larger than 2 mm were damaged by the pump rotors, but their identification was still possible, while smaller representatives of the Copepoda (Crustacea) passed the rotors without damage. A nearby artesian borehole was sampled on 6 occasions. Water chemistry, physical properties and faunal composition analyses were carried out for each borehole. A total of 32 taxa, 24 of which were stygobites, were identified. Copepoda alone were represented by 16 species, 15 of which were stygobites. The shallow boreholes differ from the deep boreholes in their higher temperatures and higher concentrations of K + , Na + , Ca 2+ , Mg 2+ and SO 4 2ions. The copepod communities in samples from the shallow boreholes differ sharply from those from the deep boreholes. There were also clear differences between shallow boreholes in two aquifers located a few kilometres apart, in physical and chemical characteristics as well as in fauna composition. Taxa with different ecological affinities, collected from groundwater, are indicators of hydraulic connections between different parts of an aquifer as well as of communication between surface and subsurface water bodies. The present study suggests that subterranean fauna, as well as epigean fauna, can provide effective support for classical dye/salt tracing experiments.
Sustainability, 2021
Assessing the effects of pollution in groundwaters is recently considered among the most relevant aims for subterranean biology; with this perspective, we aim to provide examples of the most relevant effects that pollution may cause on stygofauna community and underline patterns deserving further investigations. We retrieved different cases in which pollution caused alteration of groundwater trophic webs, favored invasions by epigean mesopredators, damaged stygobiont keystone species, and promoted interspecific competition between stygobionts and epigean animals. The results and the remarks derived from our perspective review underline that pollution may play multifaceted effects on groundwaters communities, and the paucity of information that exists on community-level changes and threats underlines the necessity for further studies.