Spring Habitats Research Articles

Molecular phylogenetic analyses reveal a radiation of freshwater Gammarus (Amphipoda: Gammaridae) in the northern Chihuahuan Desert

Abstract Isolation of desert springs often leads to the evolution of unique biodiversity. We investigated the taxonomy and evolutionary relationships of members of the Gammarus pecos complex, an assemblage of narrowly endemic amphipod species in the Chihuahuan Desert of the USA. Morphological and molecular phylogenetic analyses, including newly obtained COI sequences from the now-extinct type population of Gammarus desperatus, reveal the presence of two undescribed species and lead to redescription of G. desperatus. Gammarus acerbatus sp. nov. is split from G. desperatus and Gammarus balmorhea sp. nov. is split from G. hyalelloides. Each of these species is endemic to a single spring system. Speciation in the Gammarus pecos complex was likely promoted by the lineage’s ties to marine/riverine systems and geological events during the Oligocene/Miocene. The additional diversity discovered within the complex highlights the effects of both habitat and evolutionary history on the processes of speciation at local and regional spatial scales. The entire complex of at least six species is imperilled due to the narrow ranges occupied by each species and human water-use that threatens the existence of their spring habitats.

Acquisition of elemental sulfur by sulfur-oxidising Sulfolobales.

Elemental sulfur (S8 0)-oxidising Sulfolobales (Archaea) dominate high-temperature acidic hot springs (>80°C, pH <4). However, genomic analyses of S8 0-oxidising members of the Sulfolobales reveal a patchy distribution of genes encoding sulfur oxygenase reductase (SOR), an S8 0 disproportionating enzyme attributed to S8 0 oxidation. Here, we report the S8 0-dependent growth of two Sulfolobales strains previously isolated from acidic hot springs in Yellowstone National Park, one of which associated with bulk S8 0 during growth and one that did not. The genomes of each strain encoded different sulfur metabolism enzymes, with only one encoding SOR. Dialysis membrane experiments showed that direct contact is not required for S8 0 oxidation in the SOR-encoding strain. This is attributed to the generation of hydrogen sulfide (H2S) from S8 0 disproportionation that can diffuse out of the cell to solubilise bulk S8 0 to form soluble polysulfides (Sx 2-) and/or S8 0 nanoparticles that readily diffuse across dialysis membranes. The Sulfolobales strain lacking SOR required direct contact to oxidise S8 0, which could be overcome by the addition of H2S. High concentrations of S8 0 inhibited the growth of both strains. These results implicate alternative strategies to acquire and metabolise sulfur in Sulfolobales and have implications for their distribution and ecology in their hot spring habitats.

The threat of groundwater pollution for petrifying springs; defining nutrient threshold values for an endangered bryophyte dominated habitat

Eutrophication by human activities is increasingly affecting ecosystem functioning and plant community composition. So far, studies mainly focus on the effects of atmospheric nitrogen deposition, surface water eutrophication or soil nutrient accumulation. Groundwater pollution of spring habitats, however, has received much less attention, although numerous papers report groundwater nutrient enrichment worldwide. This study presents a survey on groundwater pollution (with emphasis on nitrate and phosphate) and bryophyte composition in 51 ambient petrifying springs in 5 NW European countries, which were compared to published data from 173 other sites in 11 European countries.The reviewed dataset covers a broad range of unpolluted to heavily polluted springs with nitrate concentrations between 0.7 and 3227 μmol l−1. Most petrifying springs in the rural lowlands of NW Europe were found to have elevated concentrations of nitrate and phosphate with the most polluted springs occurring in The Netherlands.The cover of individual characteristic bryophyte species significantly correlates with groundwater nutrient concentrations indicating that nutrient pollution of spring waters affects bryophyte composition. Palustriella commutata, Eucladium verticillatum and Brachythecium rivulare prefer unpolluted petrifying springs whereas Cratoneuron filicinum and Pellia endiviifolia show a much broader tolerance to groundwater pollution. In order to sustain at least the basic conditions for the typical bryophyte composition of petrifying springs habitats, threshold values of 288 μmol (18 mg l−1) NO3− l−1 and 0.42 μmol (0.04 mg l−1) ortho-PO43- l−1 were defined.Data analysis of the spring water composition indicates that the main source for nutrient and nutrient induced base cation enrichment are nitrate losses from intensively used agricultural fields. The anthropogenically induced but regionally different chemical processes in subsoil and aquifers can result in different levels of nutrient pollution in springs.Further regulations for nitrate and phosphate application are required to conserve and restore groundwater fed ecosystems in Europe.

An improved protocol for metagenomic DNA isolation from low microbial biomass alkaline hot-spring sediments and soil samples.

High-quality, humic-acid-free pure DNA is a prerequisite for functional and sequence-based approaches of metagenomics. In the present investigation, an improved extraction buffer was developed by making a combination of powdered activated charcoal (2%; w/v), polyvinyl poly pyrrolidone (2%; w/v), and CaCl2 (2%; w/v). This trio significantly improved the purity and yield of the metagenomic DNA from the hot spring's hot and alkaline soil. The quality of extracted metagenomic DNA was successfully validated by PCR amplification and restriction enzymes. Besides, the thermophilic amylase encoding genes were also retrieved from these soil DNA samples. Extreme habitats I harbour low microbial biomass and, therefore, demand in-situ lysis of the microbial cells to access their genomes. The protocol can potentially extract DNA from geothermal spring habitats where the count of microbial cells is low.

Panguiarchaeum symbiosum, a potential hyperthermophilic symbiont in the TACK superphylum

The biology of Korarchaeia remains elusive due to the lack of genome representatives. Here, we reconstruct 10 closely related metagenome-assembled genomes from hot spring habitats and place them into a single species, proposed herein as Panguiarchaeum symbiosum. Functional investigation suggests that Panguiarchaeum symbiosum is strictly anaerobic and grows exclusively in thermal habitats by fermenting peptides coupled with sulfide and hydrogen production to dispose of electrons. Due to its inability to biosynthesize archaeal membranes, amino acids, and purines, this species likely exists in a symbiotic lifestyle similar to DPANN archaea. Population metagenomics and metatranscriptomic analyses demonstrated that genes associated with amino acid/peptide uptake and cell attachment exhibited positive selection and were highly expressed, supporting the proposed proteolytic catabolism and symbiotic lifestyle. Our study sheds light on the metabolism, evolution, and potential symbiotic lifestyle of Panguiarchaeum symbiosum, which may be a unique host-dependent archaeon within the TACK superphylum.

Virus-to-prokaryote ratio in spring waters along a gradient of natural radioactivity

Although a strong link between viruses and prokaryotes is commonly known to exist in aquatic systems, few studies have investigated their relationship in spring waters. In the French Massif Central, certain springs are known to exhibit varying levels of naturally occurring radioactivity. Therefore, the aim of this study was to examine the standing stock of viruses together with prokaryotes and determine the potential environmental factors influencing them in springs characterized by contrasted radioactivity gradient. Among the investigated 15 spring habitats, flow cytometry analyses indicated that both viral (VA) and prokaryotic abundances (PA) varied by an order of magnitude accompanied by virus-to-prokaryote ratio ranging between 8 and 144.2. Significant differences in VA was evident among springs where low abundances (mean ± SD: 21.3 ± 7.0 × 107 VLP l−1) corresponded to high (mean ± SD: 1911 ± 814.0 nGy h−1) gamma (γ) dose radiation (222Rn) and vice versa. Adverse effect of water radioactivity (222Rn) on VA could perhaps corroborate our hypothesis of drastic effect of ionizing radiations on viruses, which might explain for lack of significant relationship between PA and VA. In such a scenario of prevailing low VA, the adopted phage life strategies could define their existence in these specialized ecosystems.

A new species of Sycorax (Sycoracinae: Psychodidae) from the Lower Eocene amber of Tadkeshwar, Gujarat, India

A new species Sycorax longistyla has been recovered in amber from the Tadkeshwar Lignite Mine, Cambay Basin, Gujarat. It belongs to the Sycoracinae, a subfamily of tiny flies, some of which prey on amphibian blood, well-preserved in the Early Eocene Cambay amber. Females of most species have functional mandibles. The new species is distinguished from the extant and extinct representatives by possessing an elongate tubular gonocoxite with a large internal lobe, the gonostylus is curved and longer than the gonocoxite and bears a strong apical spine 0.6 times the length of the gonostylus. The species occurred in sludge-based peat bog spring habitats that existed in the Early Eocene tropical angiosperm Cambay forest.

A Strategy for Conservation of Springsnails in Nevada and Utah, USA

The Nevada and Utah Springsnail Conservation Strategy (the Strategy) is a comprehensive and proactive 10-year plan to protect 103 species of truncatelloidean springsnails and their habitats (primarily springs). Springsnails are tiny, aquatic, and often locally endemic truncatelloidea and cerithioidean snails threatened by both local and regional stressors. A bi-state agreement (the Agreement) was forged by state and federal agencies and The Nature Conservancy (TNC) in 2018 in a manner consistent with U.S. Fish and Wildlife Service (USFWS) conservation criteria. Successful achievement of Agreement objectives will protect springsnails and their habitats in the two states, precluding the need for a federal listing of those species. The objectives of the Agreement are to: (1) compile springsnail ecology and distribution data into a single database; (2) identify, assess, and reduce threats to the taxa and their habitats; (3) maintain, enhance, and restore spring habitats; (4) develop and maintain a springsnail conservation team (SCT); and (5) create an effective education and outreach program for landowners, agencies, and the general public. The SCT held in-person and multiple virtual meetings in 2019–2020 to initiate the Strategy, introduce and clarify member roles, and pursue the integration of available information. The SCT assembled information and literature on each taxon in the two states into the Springs Online database (springsdata.org), a password-protected, easily used online information management system for archiving and reporting on springs-dependent species taxonomy, distribution, associated species, and population and conservation status data. The information gathered was used to generate conservation reports for individual species that can be readily updated as new information emerges. Within each Agreement objective, we describe issues to ensure springsnail species representation, resiliency, and redundancy, which are USFWS metrics of population integrity. We describe springsnail diversity and distribution, the threats and challenges to effective springsnail conservation, and the process the SCT is using to address those issues. Development of the Strategy enables the SCT to monitor, prioritize, and readily report on springsnail conservation progress over the decadal life of the Agreement. As one of the largest springs and springs-dependent species conservation efforts in the world, the context and development of the Strategy provide key lessons for other such efforts.

Activity of stygobionts in spring habitats: behavioral, ecological and evolutionary insights

Cave-dwelling animals might be regarded as dead-end points when it comes to their evolution and habitat exploitation. However, in the past different observations of the olms’ typical troglomorphic populations have been reported for springs of Venetia Giulia, along with a community rich in stygobionts (Bressi et al. 1999; Stoch 2017). The aim of this work is to point out the non-random active use of surface habitats by this community, providing a comparison with the occurrence observed in caves and performing an assessment of factors favouring ecotone habitats exploitation. Since 2020 we started multiple day and night surveys of olms in both 71 springs and 11 caves. Each spring and cave habitat monitored has been characterised by respect to abiotic and biotic features, including planktonic and benthic prey availability. Additionally, cave and spring populations of Troglocaris sp. were tested to determine whether they showed any behavioral difference regarding their response to light stimuli and predatory cues, as potential adaptations to the different conditions found in the two habitats. We used 34 individuals sampled from three springs and 24 from two caves of the Italian karst. We detected the olm at least once in 12 springs, with a maximum of 9 individuals occurring together. Detection probability in springs and caves was similar. Spring habitats provided higher density of potential prey available. Olms seem to prefer springs without predator fish and temporary hydroperiod. We recorded in one spring a larva of 3.5 cm which could be the smallest ever recorded in the field. Preliminary results of the behavioral experiments show no susceptibility to light neither for spring nor cave populations of Troglocaris sp., as for chemical cues we expect a difference in reactivity depending on the habitat of origin of the shrimp, consistently with the top predator present. We suggest that epigean habitats and borders with surface may have an underestimated importance for animals adapted to subterranean environments (Manenti and Piazza 2021), including the olm. Further studies focusing on the ipogean community which actively exploits spring habitats are underway, with the aim of determining the diel occupation of these complex ecotones.

The morphology of the colonizers of the springs from the down-under

Transition from surface to subterranean environment generally results in easily detectable morphological changes, generally referred as troglomophism. Although the cave colonisation history of species can differ considerably, in certain cases there is a possibility to directly examine the cave-induced morphological and life history changes, as some of the troglobiont and stygobiont species still have closely related surface species. A less common and therefore less known phenomenon is the invasion in the opposite direction, when cave-adapted species establish stable populations (and later, new species) in surface or surface-connected (ecotonal) habitats. A great model taxon to study if morphological changes occur in such cases is the Niphargus genus, which primarily comprises subterranean species, although some species successfully colonised surface or ecotonal habitats. To get insight of morphological changes and whether these changes were affected by sex, we measured 15 functional morphological traits on 488 individuals from both sex of eight Niphargus species, out of which four inhabit ecotonal (spring) habitats, while the other four are exclusively subterranean. We analysed our data trait-by-trait with linear mixed models. We found that colonising the “new” habitat did not demonstrably affect morphology. In contrast habitat dependent sexual dimorphism was found in case of the 2nd gnathopods’ coxa. Besides the aforementioned habitat dependent sexual dimorphism, we found sexual dimorphism in case of 11 out of the 15 traits. Based on our result we can assume that morphological changes might happen in the course of the colonisation of the novel habitat, but they are not as unambiguous as when surface species colonise caves. It is also possible that although we consider springs as ecotone or even surface habitats, they might be feasible for subterranean species without striking morphological changes as they do not meet selection forces strikingly different from those present in caves.

Preliminary study on differences characterizes the populations of olm (Proteus anguinus) in cave and those found in epigean environment

The olm (Proteus anguinus) is considered the most representative example of all the stygobiont fauna. Nevertheless, it is also reported in some spring habitats of Friuli Venezia Giulia (North-eastern Italy). Springs are intriguing habitats that border two strongly distinct environments: surface and underground. They may provide distinct environmental pressures to stygobiont animals promoting new adaptations. The aim of this study is to verify if there are differences in the structural morphology of the head and in the presence of melanin in the skin between the olms that are found in caves compared to the individuals found in the external environment. During 2021, 28 olms, 18 from underground habitats and 10 from external sites, were photographed in standard conditions with a metric reference. For each individual, only the cephalic region has been considered. The pictures were processed using TPSdig software. For each picture we placed 2 landmark homologues, matching the emergence of the gills branches, and 48 semi-landmark to define the contour of the head. With regard to melanin 2 mm of skin were removed from the tail of the olm and analyzed through a spectrophotometer. The results indicate a significant effect of the environment on the shape of the olm’s head, in fact the shape of the head appears more elongated in the front and narrower in the parietal region in the olms coming from the hypogean environment. In addition, the olms that use the epigean environment show higher melanin levels in their skin. These findings provide a first evidence of differences occurring between olm populations/sub-populations living in caves and those exploiting surface habitats.

The roles of landscape of fear and light in allowing the exploitation of spring habitats by subterranean amphipods: an experimental and field approach

Border habitats such as interfaces and ecotones promise research targets from an evolutionary and zoological point of view. Springs are typical ecotones that border two strongly distinct environments: surface and underground. They are exploited by both subterranean and surface species for which they may provide specific environmental pressures promoting phenotypic plasticity and local adaptations. The aim of this study is to understand how the landscape of fear (LOF) and physical constraints, like light occurrence, affect springs' exploitation by both a subterranean (Niphargus thuringius) and a surface crustacean amphipod species (Echinogammarus stammeri). From March to May 2021, we surveyed 15 springs, divided into 25 plots according to their distance to the border, and both day and night, we recorded amphipods activity and LOF levels for them. In a subterranean laboratory, we also reared 80 N. thuringius and 80 E. stammeri in safe and risky conditions with constant darkness and diel light variation assessing their activity and survival for 30 days. Risky conditions were represented by meso-predators (four fire salamander larvae) alone or with a top-predator (a dragonfly larva of the species Cordulegaster boltonii). While in field conditions, the activity of N. thuringius seemed negatively affected by the number of active predators, in laboratory experiments, the main role was played by the light treatment; activity was significantly higher in constant darkness conditions. E. stammeri activity in the field was higher in surface plots, while in laboratory conditions was affected by LOF. Predation risk negatively affected the survival of both amphipods. Our findings reveal that while light conditions seem to shape activity patterns of stygobionts strongly, predators have a lower effect on activity, even though predators have negative effects on survival. Moreover, physical constraints, such as light exposure, can affect antipredator responses of subterranean organisms, thus representing selective pressures for the exploitation of surface environments.

Dramatic decline of two freshwater killifishes, main anthropogenic drivers and appropriate conservation actions

Freshwater fish biodiversity loss in the Mediterranean Basin is regarded as among the highest globally, with long-term population data sets required to discern long-term population trends of threatened species, in order to design appropriate conservation interventions. In this study, we assessed the population trends of two threatened freshwater fishes, Valencia letourneuxi and Valencia robertae, employing the most recent and largest compiled database to date (16 populations over 14 years). We applied the innovative methodology of the Living Planet Index (LPI) to assess the average rate of change over time across a set of V. letourneuxi and V. robertae populations in Greece. The LPI application revealed a dramatic decline of both species, with V. letourneuxi declining by 97.7% and V. robertae by 91.0%. Beta regression showed that water pollution, eutrophication and alien Eastern mosquitofish Gambusia holbrooki’ presence were the three best fitting predictors of the decline of V. letourneuxi and V. robertae populations. Based on the above, we outline the conservation measures urgently required to revert the near collapse of the populations of the two species. Conservation actions include the strict protection of the their lowland spring habitats, habitat improvement through changes in water management and agricultural practices, mosquitofish invasion prevention and mosquitofish impact mitigation measures, as well as translocation actions and captive breeding. Lastly, the association patterns of the proposed conservation actions with anthropogenic pressures and their expected outcomes were analysed through an alluvial diagram, providing insights on the scale of pressures mitigated by conservation actions and on their conservation benefits.

Environmental heterogeneity, dispersal mode and habitat specialisation modify within‐site beta diversity of spring macroinvertebrates

AbstractSpring helocrenes are a unique aquatic environment with high biotic diversity. Although environmental heterogeneity has traditionally been assumed to explain the high species richness of spring habitats, this assumption has never been properly tested. Here, we sampled macroinvertebrates from two calcareous helocrenes in Slovakia with visually distinguishable mesohabitat heterogeneity. We hypothesise that macroinvertebrate beta diversity significantly increases with environmental heterogeneity even at a small within‐site spatial scale. We also examined four species‐trait categories, that is, active or passive dispersers and habitat specialists or generalists. Significant spatial structuring of environmental heterogeneity was found at one site, whereas the other site did not show a clear spatial pattern. Strong associations were found between beta diversity of all species trait categories and environmental heterogeneity at the first site, while there were virtually no associations at the second site. Specialists were not spatially structured at any of the sites examined. Our results suggest that invertebrate beta diversity responds positively to environmental heterogeneity at a site by also tracking spatial structuring of abiotic conditions. However, the response may vary depending on the dispersal mode and habitat specialisation of the invertebrates.

Changes in plant community and soil properties mediated by grazing in semi-desert of Mongolia

Recent increases in livestock numbers throughout Mongolia could alter plant communities, soils of habitats differed by landscape position. We aimed to determine the impact of large herbivore grazing on some soil properties and plant communities’ richness and of the four different habitats within the Ikh Nart Nature Reserve. The highest plant species richness and evenness was observed around the rocky outcrop habitats, followed by shrublands, then the spring, and finally by the well habitat. Soils at habitats around and close to water points are compacted and have lower organic matters compared to the less grazed habitats. The data indicates that the highest overlap between livestock and wild ungulates occurs near spring habitats, which increases vulnerability to local land degradation. Therefore, the study results suggest that appropriate land-use management is required in the semi-desert regions across Mongolia. There is a necessity to initiate an extensive grazing ecological management that reflects the sustainable grazing of large herbivores, the benefits to herder households, and the ecosystem’s service.

Intra‐Alpine Islands: Population genomic inference reveals high degree of isolation between freshwater spring habitats

AbstractAimAlpine spring ecosystems have long been considered as highly isolated, island‐like habitats. This presumption, however, is insufficiently supported empirically and conclusions about spring isolation have been based on indirect evidence. Therefore, we investigated the population genomic structure of Partnunia steinmanni Walter, 1906, a strictly spring‐dwelling water mite (Hydrachnidia) species, to shed light on the degree of interconnection among freshwater spring habitats.LocationProtected areas across the Alps, Central Europe.MethodsPartnunia steinmanni populations were sampled by hand‐net from 12 springs. Population genomic structure was inferred with 2263 polymorphic restriction site‐associated DNA (RADseq) loci of 256 individuals. We assessed genomic admixture, the phylogenetic relationship, isolation by distance, contemporary migration, effective population sizes, and genetic diversity among individuals from different springs.ResultsWe observed strong genetic differentiation between individuals from different springs. Water mites from each spring qualified as well‐delimited distinct populations with only little intra‐spring migration, even when these were located in close geographic proximity. Furthermore, we found subtle shared genetic structure among springs within the same area, and a southwestern genotype associated with the Rhône catchment that extended into eastern populations. Effective population size estimates and standing genetic variation within springs were generally low.Main conclusionsOur findings indicate strong insularity of freshwater springs and headwater areas, likely caused by intra‐alpine Pleistocene isolation and limited dispersal abilities of strictly spring‐bound species like P. steinmanni. Our results support the concept of spring habitat isolation and highlight the importance of alpine protected areas to conserve springs as substantial components of freshwater biodiversity.

Regional typology of spring vegetation in Parc Ela (Grisons, Switzerland)

Aims: The spring habitats of Central Europe are insular biotopes of high ecological value. Although subject to severe exploitation pressures, they do not yet have a comprehensive protection status in Switzerland. Contributing to this challenge is the controversy involved with their syntaxonomic classification. In the context of the development of a regional conservation strategy and the establishment of a national inventory of Swiss springs, we carried out a regional survey of spring vegetation and aimed to translate this into a classification system.Study area: Montane and subalpine zones of Parc Ela (Grisons, Switzerland).Methods: We selected 20 springs to cover different regions, elevations and bedrock types within the park. In each of them we recorded complete vascular plant and bryophyte composition as well as a range of environmental variables in three 1-m² plots that were placed to reflect the heterogeneity within the spring. After running an unsupervised classification with modified TWINSPAN, the distinguished vegetation units were characterized in terms of diagnostic species, species richness and environmental variables and placed within the syntaxonomic system.Results: Species richness was high (total species 264, mean 21.7 species in 1 m2). The two most important environmental gradients of the ordination were elevation/water conductivity and insolation/water pH/soil reaction EIV. We distinguished seven communities within two main groups.Conclusions: All unshaded springs, including those over siliceous bedrock, could be assigned to a broadly definedCratoneurion. The petrifying springs were not strongly distinguishable floristically from other base-rich springs. The forest springs, although often not clearly differentiated from their unshaded counterparts, could be provisionally divided into the alliancesCaricion remotaeandLycopodo europaei-Cratoneurion commutati. As there is a certain threat to these habitats in the park due to anthropogenic influence, protection measures are recommended, most importantly the appropriate management of alpine pastures.Taxonomic reference: Juillerat et al. (2017) for vascular plants, Meier et al. (2013) for bryophytes.Abbreviations: ANOVA = analysis of variance; DCA = detrended correspondence analysis; EIV = ecological indicator value; FOEN = Federal Office of the Environment (Switzerland); NCHO = Ordinance on the Protection of Nature and Cultural Heritage; SD = standard deviation; TWINSPAN = Two Way Indicator Species Analysis; WPA = Federal Act on the Protection of Waters.

Three New Diatom Species from Spring Habitats in the Northern Apennines (Emilia-Romagna, Italy)

Using light (LM, including plastid characterization on fresh material) and scanning electron microscopy (SEM), as well as a thorough morphological, physical, chemical, and biological characterization of the habitats, the present study aims at describing three species new to science. They belong to the genera Eunotia Ehrenb., Planothidium Round and L. Bukht., and Delicatophycus M.J. Wynne, and were found in two contrasting spring types in the northern Apennines. The three new species described differ morphologically from the most similar species by: less dense striae and areolae, and the absence of a ridge at the valve face-mantle transition (SEM feature) [Eunotia crassiminor Lange-Bert. et Cantonati sp. nov.; closest established species: Eunotia minor (Kütz.) Grunow]; narrower and shorter cells [Planothidium angustilanceolatum Lange-Bert. et Cantonati sp. nov.; most similar species: Planothidium lanceolatum (Bréb. ex Kütz.) Lange-Bert.]; barely-dorsiventral symmetry, set off ends, and lower density of the central dorsal striae [Delicatophycus crassiminutus Lange-Bert. et Cantonati sp. nov.; most similar species: Delicatophycus minutus M.J.Wynne]. Two of the three species we described are separated from the closest species by dimensions. Their description improved knowledge on two taxa (Eunotia minor s.l. and Planothidium lanceolatum s.l.) likely to be only partially resolved species complexes. We could also refine knowledge on the ecological profiles of the three newly-described species. Eunotia crassiminor sp. nov., as compared to Eunotia minor, appears to occur in colder inland waters with a circumneutral pH and a strict oligotrophy as well with respect to nitrogen. The typical habitat of Planothidium angustilanceolatum sp. nov. appears to be oligotrophic mountain flowing springs with low conductivity. Delicatophycus crassiminutus sp. nov. was observed only in limestone-precipitating springs, and is therefore likely to be restricted to hard water springs and comparable habitats where CO2 degassing leads to carbonate precipitation. Springs are a unique but severely threatened wetland type. Therefore, the in-depth knowledge of the taxonomy and ecology of characteristic diatom species is important, because diatoms are excellent indicators of the quality and integrity of these peculiar ecosystems in the face of direct and indirect human impacts.

Comparative Genomics Reveals Thermal Adaptation and a High Metabolic Diversity in "Candidatus Bathyarchaeia".

ABSTRACT“Candidatus Bathyarchaeia” is a phylogenetically diverse and widely distributed lineage often in high abundance in anoxic submarine sediments; however, their evolution and ecological roles in terrestrial geothermal habitats are poorly understood. In the present study, 35 Ca. Bathyarchaeia metagenome-assembled genomes (MAGs) were recovered from hot spring sediments in Tibet and Yunnan, China. Phylogenetic analysis revealed all MAGs of Ca. Bathyarchaeia can be classified into 7 orders and 15 families. Among them, 4 families have been first discovered in the present study, significantly expanding the known diversity of Ca. Bathyarchaeia. Comparative genomics demonstrated Ca. Bathyarchaeia MAGs from thermal habitats to encode a large variety of genes related to carbohydrate degradation, which are likely a metabolic adaptation of these organisms to a lifestyle at high temperatures. At least two families are potential methanogens/alkanotrophs, indicating a potential for the catalysis of short-chain hydrocarbons. Three MAGs from Family-7.3 are identified as alkanotrophs due to the detection of an Mcr complex. Family-2 contains the largest number of genes relevant to alkyl-CoM transformation, indicating the potential for methylotrophic methanogenesis, although their evolutionary history suggests the ancestor of Ca. Bathyarchaeia was unable to metabolize alkanes. Subsequent lineages have acquired the ability via horizontal gene transfer. Overall, our study significantly expands our knowledge and understanding of the metabolic capabilities, habitat adaptations, and evolution of Ca. Bathyarchaeia in thermal environments.IMPORTANCE Ca. Bathyarchaeia MAGs from terrestrial hot spring habitats are poorly revealed, though they have been studied extensively in marine ecosystems. In this study, we uncovered the metabolic capabilities and ecological role of Ca. Bathyarchaeia in hot springs and give a comprehensive comparative analysis between thermal and nonthermal habitats to reveal the thermal adaptability of Ca. Bathyarchaeia. Also, we attempt to determine the evolutionary history of methane/alkane metabolism in Ca. Bathyarchaeia, since it appears to be the first archaea beyond Euryarchaeota which contains the mcrABG genes. The reclassification of Ca. Bathyarchaeia and significant genomic differences among different lineages largely expand our knowledge on these cosmopolitan archaea, which will be beneficial in guiding the future studies.

Flood Pulsing in Restoration : A Feasible Alternative for India?

The full restoration of natural flood pulsed conditions has only been attempted in a few places in the world because the politics behind the original destruction of the wetland generally impedes full restoration. Often the desire to restore wetlands for wildlife and other purposes is not strong enough to alter or eliminate the engineering projects such as embankment, diversion, interbasin water transfer and hydroelectric dams for water, irrigation and electricity that destroyed the original wetland. Unfortunately, we must find ways to provide plant and animal species flood pulsed habitats because many of these are not only adapted to, but dependent on this environment for their continued survival.The restoration of flood pulsing has been accomplished only in a handful of places such as the Kissimmee River (Florida U.S.A.) and the Lodi Wildlife Area (Wisconsin U.S.A.). At the same time, many partial restorations have been successful removing or working with engineering projects. After the floods of the Mississippi River (U.S.A.), many people moved off the flood plain with the blessing of the Federal Emergency Management Agency. Now, several embankments (levees or bunds) have been removed, and areas are reverting to natural vegetation. Downstream from hydroelectric dams in the Cameroon (Africa) and near Pune (India), impounded borrow areas with bunds have created fisheries/vegetable gardens and wildlife habitat, respectively. Restoration of spring habitats in arid and montane regions can be as simple as removing cattle from the banks of streams as in the case of the Magic Spring near Cartago (Costa Rica). The inclusion of flood pulsing in riverine restoration in India is a new idea as it is everywhere, but we must give serious consideration to recreating the original conditions of the habitat for the benefit of the animals and plants that utilize these wetlands.