Distribution Of Tardigrades Research Articles

Distribution of tardigrade cryptobiotic abilities across a fine-scale habitat gradient

AbstractIn this study, we examine the distribution of cryptobiotic abilities, specifically anhydrobiosis and cryobiosis, in tardigrade communities across a habitat gradient from the edge to the centre of a forest bordering a desert. Our study demonstrates no correlation between desiccation and freezing tolerance at the community level. However, communities inhabiting the forest centre show higher cryptobiotic performance, likely due to better energy reserves indicated by slower mortality rates during fasting. The observed distribution pattern of cryptobiotic abilities cannot be explained by differences in community compositions or body sizes, as these variables were uniform across the gradient. Our research highlights the significance of environmental factors in shaping cryptobiotic responses and sheds light on the functional characteristics underlying the distribution of tardigrades in fine-scale habitat gradients. Our findings also challenge the hypothesis of a correlation between desiccation and freezing tolerance in cryptobiotic organisms.

Tardigrade distribution in soils of high Arctic habitats.

Tardigrades are omnipresent microfauna with scarce record on their ecology in soils. Here, we investigated soil inhabiting tardigrade communities in five contrasting polar habitats, evaluating their abundance, diversity, species richness, and species composition. Moreover, we measured selected soil physico-chemical properties to find the drivers of tardigrade distribution among these habitats. In spite of reported tardigrade viability in extreme conditions, glacier forelands represented a habitat almost devoid of tardigrades. Even dry and wet tundra with soil developing for over more than 10000 years held low abundances compared to usual numbers of tardigrades in temperate habitats. Polar habitats also differ in species composition, with Diaforobiotus islandicus being typical species for dry and Hypsibius exemplaris for wet tundra. Overall, tardigrade abundance was affected by the content of nutrients as well as physical properties of soil, i.e. content of total nitrogen (TN), total organic carbon (TOC), stoniness, soil texture and the water holding capacity (WHC). While diversity and species composition were significantly related to soil physical properties such as the bulk density (BD), soil texture, stoniness, and WHC. Physical structure of environment was, therefore, an important predictor of tardigrade distribution in polar habitats. Since many studies failed to identify significant determinants of tardigrade distribution, we encourage scientists to include physical properties of tardigrade habitats as explanatory variables in their studies.

Removal of historical taxonomic bias and its impact on biogeographic analyses: a case study of Neotropical tardigrade fauna

Abstract Large-scale databases are crucial for macroecology research, yet not entirely bias-free. Studying the biogeography of metazoan microfauna utilizing such databases is challenging, and added biases can further hinder them. Incidence data of tardigrade species from Central and South America are geographically biased, comprising mostly species erroneously considered cosmopolitan. The impact of these biases on macroecological studies is still unknown. This paper evaluates how biased distribution records affect understanding of non-marine tardigrade distribution patterns in the Neotropical region. Using two datasets (including and excluding dubious records of allegedly cosmopolitan species), we assess how well biogeographic regions are sampled, estimate tardigrade species’ richness, and analyse whether including dubious records can alter our comprehension of their macroecology. We demonstrate how biogeographic regions are still not fully sampled, and that including unreliable records influences how many species remain to be discovered. Since records of ‘false cosmopolitan species’ represent most records, their removal increases uncertainty while yielding distribution patterns more likely to be accurate. Disregarding untrustworthy distribution records of ‘false cosmopolitan species’ is the first step to better understanding tardigrade macroecology in the Neotropics, and probably worldwide. However, additional, preferably systematic sampling is required before we can infer general tardigrade biodiversity patterns in under-sampled regions.

Deep-Sea Tardigrades from the North-Western Pacific, with Descriptions of Two New Species

Three deep-sea tardigrade species were identified from the sediment samples collected during the four German–Russian joint deep-sea cruises that were conducted in the North-Western Pacific: Coronarctus sonne sp. nov., Moebjergarctus okhotensis sp. nov., and Angursa cf. bicuspis. Specimens of those species were collected at depths between 1700 and 5410 m. The new species Coronarctus sonne sp. nov. belongs to the Cor. tenellus group of species on the basis of morphological traits such as the short cephalic appendages and heteromorphic claws. The structure of the secondary clavae and two points, with an accessory point and a primary point simultaneously on the internal and external claws on legs IV, are significant characteristics distinguishing Coronarctus sonne sp. nov. from other described species. Moebjergarctus okhotensis sp. nov. is characterized by having cephalic cirri with the long smooth portion of the scapus and annulated scapus only in the basal portion, the structure of the male and female reproductive system, and differences in the sizes of some structures compared to the other described species. An analysis of the results of four deep-sea expeditions indicates a patchy distribution of tardigrades in the North-Western Pacific.

The Genus Milnesium Doyère, 1840 in Mexico with Description of a New Species

Knowledge of the diversity and distribution of tardigrades in Mexico is limited. Up to now 79 taxa of limno-terrestrial, freshwater and marine tardigrades were reported (including three species of Milnesium) from the country. We examined a total of 73 specimens of the genus Milnesium collected from mosses and lichens in northeastern Mexico. The analysed specimens represent four species, of which one was previously unknown, and is described in this paper. Milnesium fridaesp. nov. has eyes, claw configuration (CC) [3–3] - [3–3], a wide and short buccal tube (standard width on average 64% of its length), and cuticle with very small pseudopores visible under high magnifications. It differs from other Milnesium species by various morphometric characteristics specified in the paper. Moreover, the ontogenetic variability of CC in new species was followed, observing that there is no variability in this character. In addition, distribution of the Milnesium species in Mexico is also discussed.

A hole in the nematosphere: tardigrades and rotifers dominate the cryoconite hole environment, whereas nematodes are missing

AbstractThe worldwide distribution of microinvertebrates on glaciers, the coldest biome, is poorly known. Owing to their tolerance to hostile conditions, small size and dispersal abilities, nematodes, tardigrades and rotifers are considered cosmopolitan and together inhabit various ecosystems. In this study, we investigated their global distribution in cryoconite holes – a type of freshwater reservoir forming directly in the glacial ice that creates biodiversity hotspots on glaciers. We analysed cryoconite samples (using classical microscopic observations and environmental DNA metabarcoding) from 42 glaciers located around the world (the Arctic, Subarctic, Scandinavia, the Alps, the Caucasus, Siberia, Central Asia, Africa, South America and Antarctica), as well as using literature data. Samples from Antarctic, Karakoram and the Alps were analysed using next‐generation sequencing (NGS) and classical observations under microscopes, while all other samples were analysed by microscope alone. Three general outcomes were found: (1) tardigrades and rotifers represented the most common invertebrates in cryoconite holes; (2) tardigrades and rotifers often coexisted together, with one or the other dominating, but the dominant taxon varied by region or by glacier; (3) nematodes – the most abundant, hyperdiverse and widespread metazoans on Earth, including in environments surrounding and seeding glacial surfaces – were consistently absent from cryoconite holes. Despite the general similarity of environmental conditions in cryoconite holes, the distribution of tardigrades and rotifers differed among glaciers, but not in any predictable way, suggesting that their distribution mostly depended on the random dispersal, extreme changes of supraglacial zone or competition. Although nematodes have been found in supraglacial habitats, cryoconite hole environments seem not to provide the necessary conditions for their growth and reproduction. Lack of physiological adaptations to permanently low temperatures (~0°C) and competition for different food resources in the cryoconite hole environment may explain the absence of nematodes in cryoconite holes.

Contribution to the Knowledge on Distribution of Tardigrada in Turkey

Tardigrades have been occasionally studied in Turkey since 1973. However, species number and distribution remain poorly known. In this study, distribution of Tardigrades in the province of Karabük, which is located in northern coast (West Black Sea Region) of Turkey, was carried out. Two moss samples were collected from the entrance of the Bulak (Mencilis) Cave. A total of 30 specimens and 14 eggs were extracted. Among the specimens; Echiniscus granulatus (Doyère, 1840) and Diaforobiotus islandicus islandicus (Richters, 1904) are new records for Karabük. Furthermore, this study also provides a current checklist of tardigrade species reported from Turkey, indicating their localities, geographic distribution and taxonomical comments.

Two new species of the genus Milnesium Doyère, 1840 (Tardigrada, Apochela, Milnesiidae) from Madagascar.

The knowledge of the diversity and distribution of tardigrades on Madagascar is rather poor. To date, only 13 tardigrade taxa have been reported from this region (including one Milnesium species). We examined 46 specimens belonging to two new-to-science species of the genus Milnesium described herein using an integrative approach, including classical morphology and molecular marker (COI, ITS-2 and 28S rRNA) analysis. The species were found in two moss and lichen samples collected in the Ivohibory forest in Fianarantsoa Province. Milnesium matheusisp. nov., with claw configuration [3-3]–[3-3] and rather wide buccal tube, morphologically is most similar to: Mil. beatae Roszkowska, Ostrowska & Kaczmarek, 2015, Mil. bohleberi Bartels, Nelson, Kaczmarek & Michalczyk, 2014, Mil. eurystomum Maucci, 1991, Mil. shilohae Meyer, 2015 and Mil. tumanovi Pilato, Sabella & Lisi, 2016; however, it differs from these by morphometric characteristics. Milnesium wrightaesp. nov., by the presence of four points on secondary branches of claws IV, is most similar to Mil. quadrifidum Nederström, 1919. However, Mil. wrightaesp. nov. differs from Mil. quadrifidum by claw configuration ([4-4]–[4-4] in Mil. quadrifidum vs. [3-3]–[4-4] in Mil. wrightaesp. nov.), but also by the position of the fourth points on secondary branches of claws IV, which are located near the base of the claw in the new species and near the top of the claw in Mil. quadrifidum. Genotypic analysis showed that Mil. matheusisp. nov. is most similar to Milnesium sp. (28S rRNA), Mil. variefidum (COI) and Mil. t. tardigradum (ITS-2) while Mil. wrightaesp. nov. is most similar to Milnesium sp. (28S rRNA), Mil. variefidum (COI) and Mil. matheusi (ITS-2). Five Milnesium taxa are recorded from the African region, including the two new species from Madagascar reported in this study.

Deep-Water Tardigrada of the Istanbul Strait’S (Bosporus) Outlet Area of the Black Sea

The results of investigations of tardigrades (2009-2010) in the Bosporus outlet area of the Black Sea are represented. For the first time two species of tardigrades Dipodarctus subterraneus (Renaud-Debyser, 1959) and Tanarctus ramazzottii (Renaud-Mornant, 1975) are recorded for the Black Sea. Tardigrades are registered on 4 stations at depths range 88-250 m. Average abundance of tardigrades widely varied from 141 to 11 440 ind./m2. The vertical distribution of tardigrades in the sediments was analyzed: most specimens (up to 98 %) found in the top 0-1 cm sediment layer.

Current knowledge of the Tardigrada of Svalbard with the first records of water bears from Nordaustlandet (High Arctic)

The first investigations of the tardigrades of Svalbard took place in the early 20th century and 30 papers on the subject have been published to date. In this article, we summarize available information on the distribution of tardigrades in this Arctic archipelago with remarks on the dubious species and records. Additionally, we examined 28 new moss, lichen and soil samples collected from the islands of Nordaustlandet, Edgeøya and Prins Karls Forland. These samples yielded 324 specimens, 15 exuvia and 132 free-laid eggs belonging to 16 limnoterrestrial species (Heterotardigrada and Eutardigrada). These include five first records of water bears from Nordaustlandet, eight new records for Edgeøya and four for Prince Karls Forland. The most dense population of tardigrades was found in a sample with 253 specimens/10 g of dry material and the least dense population in a sample with three specimens/10 g of dry material. The most frequently recorded species in samples collected in this study were Testechiniscus spitsbergensis Scourfield, 1897, Macrobiotus harmsworthi harmsworthi Murray, 1907, and M. islandicus islandicus Richters, 1904. This article also provides the first ever scanning electron microscope photomicrographs of Tenuibiotus voronkovi Tumanov, 2007.Keywords: Checklist; Edgeøya; new species; Prins Karls Forland; soil fauna; Svalbard biodiversity(Published: 20 November 2013)To access the supplementary material for this article, please see Supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2013, 32, 20886, http://dx.doi.org/10.3402/polar.v32i0.20886

Diversity and distribution of tardigrades in soils of Edmonson Point (Northern Victoria Land, continental Antarctica)

This work contributes to the knowledge on distribution, diversity and ecology of the Antarctic soil biota. Different soil habitats from several ice-free coastal sites were sampled along the Victoria Land across 7° of latitude from 71° to 78°S during five austral summer seasons between 2003/04 and 2011/12. In this paper we report preliminary data on soil tardigrades (water bears) from Edmondson Point, Northern Victoria Land. Tardigrades were found to be present in 23 of the 41 examined soil samples (56%). Their presence was associated exclusively with soil samples collected from bryophytes communities and under cyanobacterial mats, whereas they were completely absent in fellfield and ornithogenic soils. Tardigrades were least numerous among all soil micrometazoans, their abundance in the positive samples was very variable and ranged from 3 to 1824 individuals per 100 g of soil DW. High water content seemed to be the major factor determining occurrence of tardigrades in the soils investigated. On the other hand low water content and toxic compounds from penguin guano seemed to act as a strong constraint on their existence in the Antarctic soils. Taxonomic evaluation of the extracted tardigrades revealed presence of only two species belonging to class Eutardigrada: Acutuncus antarcticus (Richters, 1904) and Milnesium antarcticum Tumanov, 2006. While A. antarcticus has already been reported previously as the most widespread and abundant tardigrade across the Victoria Land, the information on M. antarcticum is novel, both for Victoria Land and the continental Antarctica.

Tardigrades of North America:Milnesium alabamaenov. sp. (Eutardigrada: Apochela: Milnesiidae) a New Species from Alabama

Milnesium alabamae nov. sp. is a new species of tardigrade described from Alabama, USA. This unique tardigrade of order Apochela and family Milnesiidae is characterized by its visibly punctuated cuticle, short, narrow buccal tube, and long primary branch of the claws without accessory points. The buccal tube appears to be only half the length of the signature species Milnesium tardigradum for animals of similar body length. The specimens add data to the questions of tardigrade distribution and evolution.

Distribution of Tardigrades in Florida

Abstract The distribution of terrestrial tardigrades in the Gulf Coast states of the United States is poorly known. Only one species has been reported in Florida. In this study, bryophyte samples (47 identified species) from trees and shrubs were collected from all 67 Florida counties. Twenty tardigrade species were found: Echiniscus cavagnaroi, E. kofordi, E. virginicus, Pseudechiniscus suillus, Ramazzottius baumanni, Diphascon (Diphascon) pingue, Macrobiotus echinogenitus, two species of Macrobiotus cf. harmsworthi, Macrobiotus cf. hibiscus, Macrobiotus hufelandi, two species of Macrobiotus cf. hufelandi, Macrobiotus islandicus, Macrobiotus occidentalis, Macrobiotus richtersi, Macrobiotus tonollii, Minibiotus fallax, Minibiotus intermedius, and Milnesium tardigradum. The distribution of tardigrade species was not correlated with Florida's ecological regions. Tardigrade species richness declined from north to south in peninsular Florida.

Limno-terrestrial Tardigrada of the Nearctic Realm

We examined all available records of limno-terrestrial tardigrade distribution in the Nearctic realm (Greenland, Canada, Alaska, the continental United States of America, and northern Mexico), both to compare this fauna with other realms and to investigate distribution within North America. We included only those records in which tardigrades had been identified to species. Of 204 Nearctic limno-terrestrial tardigrade species, 38 were cosmopolitan, while 55 were unique to the Nearctic realm. The Nearctic tardigrade fauna is most similar to the Palearctic, with 135 species in common, 39 of which have not been reported elsewhere. The Nearctic realm shares 82 species with the Neotropical realm, only 10 which are not also Palearctic. These data are consistent with the geological history of the three realms, and indicate a distinction between Laurasian and Gondwanan tardigrade faunas. Although little is known about limno-terrestrial tardigrade distribution in much of North America, there are several excellent regional or local surveys. Many species are distributed widely throughout the continent, but 30.0% of Nearctic species have been reported from a single site. Cluster analysis of the fauna of 11 Nearctic regions shows that the Arctic and sub-Arctic fauna constitute a regional fauna distinct from the rest of the continent. Ecological analysis is hampered by inconsistent reporting of tardigrade substrate, though available data suggest little substrate specificity in terrestrial tardigrades. Most species are found in both mosses and lichens. Many are also present in soil and leaf litter, but few are found only in these substrates.

Tardigrade species composition in young soils and some aspects on life history of Macrobiotus richtersi J. Murray, 1911

Summary In an afforested coal-mining site at Berzdorf, Germany, the soil tardigrade community was investigated. Tardigrade densities ranged from 300 to 33,600 individuals m −2 . Tardigrade distribution was very aggregated with standard deviations of up to 220% of mean densities. Fourteen species belonging to five eutardigrade genera were identified. Soils were dominated by the carnivorous tardigrade Macrobiotus richtersi that contributed 60% of overall densities. A comparison between nine soils of different forest ages (4–46 years) and tree species (poplar, alder, pine, mixed deciduous and mixed coniferous) showed no relationship of tardigrade species distribution and abundance to tree species, thickness of organic or litter layer, humus form, pH or soil moisture. Further, no correlation between nematode biomass and Macrobiotus richtersi abundances were detected. The age of afforested soils, however, affected tardigrade densities: younger soils (7–17 years) yielded higher tardigrade numbers compared to 46-year-old sites. Life history investigations on a strain of parthenogenetic Macrobiotus richtersi demonstrated a significant influence of temperature on egg development, survival rate, body growth and generation time. Hatching, first to fourth molts and maturing, on the other hand, were dependent upon body size alone. The simple, new culture method for carnivorous tardigrades described has successfully been utilized for parthenogenetic Macrobiotus richtersi for 6 years.

Tardigrade Distribution in a Medium-sized City of Central Argentina

The distribution and abundance of tardigrades in the city of General Pico (Argentina) are analyzed from samples collected during autumn and spring 2001. Sample sites included paved urban locations with different traffic intensities, non-paved periurban places, and places with peculiar conditions such as the city industrial area and the bus station. Trees of the same species were selected in each area and from each of them nine subsamples of lichens and/or moss, 11 mm in diameter, were taken with steel corers. The diversity, density and relative abundance of tardigrades was recorded and analyzed. Sampling sites were ordinated and classified with PCA and clustering. The number total of species collected in the research was 5. The maximum number of species per site and per tree was 4. The species recorded were: Echiniscus rufoviridis, Milnesium cf. tardigradum, Ramazzottius oberhaeuseri, Macrobiotus areolatus and an undescribed species of the genus Macrobiotus. The average density was approximately 10 specimens per cm2 and the maximum values reach over 50 specimens per cm2. R. oberhaeuseri and M. cf. tardigradum were the most frequent species. R. oberhaeuseri dominates in periurban areas with high suspension dust and very exposed to the sun. M. cf. tardigradum dominates on paved streets with intense vehicle traffic. Results supported the hypothesis of the relationship between air quality and tardigrade diversity.

Water-bears from the Rocky Mountains: A First Look at Alberta's Tardigrade Fauna

There is no information in the published literature regarding Alberta’s terrestrial water-bear (Tardigrada) fauna. We surveyed across an elevational gradient (1100 – 1800 ft) on Black Cat Mountain in the Alberta Rocky Mountain range. Ten taxa were identified from 902 specimens, all of which are new records for Alberta and one species is new for Canada: Macrobiotus cf. islandicus Richters, 1904. There was no clear relationship between elevation and tardigrade distribution, possibly owing to patchiness of these animals in the field and lack of adequate replication at each elevation.

Diversity and distribution of tardigrades (Bilateria, Tardigrada) from the Iberian Peninsula, Balearic Islands and Chafarinas Islands

Bibliographical information on the Tardigrada from Iberian Peninsula, Balearic Islands and Chafarinas Islands is compiled herein. 118 species are listed from the studied area. The first records of six Tardigrada species, Dactylobiotus parthenogeneticus, Dactylobiotus selenicus, Murrayon dianeae, Diphascon (Diphascon) nodulosum (first time in Europe), Diphascon (Diphascon) pingue and Isohypsibius marcellinoi that had not previously been found in the area are included. Bibliography data are analysed. After the analysis, it is concluded that more intensive, extensive and within more diverse habitats sampling effort should significantly increase the knowledge of tardigrade diversity in the studied area.

Distribution of Tardigrades within a Moss Cushion: Do Tardigrades Migrate in Response to Changing Moisture Conditions?

The distribution of tardigrades within the layers of the cushion moss Grimmia alpicola Hedwig, 1801 was investigated. The aim of this study was to determine the tardigrade species present within the moss layers during both wet and dry periods and to determine if migration occurred in response to changing moisture conditions. Samples of the moss were removed from concrete caps on brick fence posts before and after rainfall and separated into two sections (top and bottom). The tardigrades from each layer and moisture condition were identified to species. Data for each species were statistically analyzed with a two-way analysis of variance (ANOVA) to compare the numbers of individuals present in the top and bottom layers of the moss under both wet and dry conditions. Five tardigrade species were identified, including two species new to science: Macrobiotus sp. n.; Milnesium tardigradum Doyère, 1840; Echiniscus viridissimus Peterfi, 1956; Echiniscus perviridis Ramazzotti, 1959; and Echiniscus sp. n. The new species will be described in a forthcoming paper. No significant differences were found in the numbers of individuals of four of the five species in each layer within the moss or for each moisture condition. Only one species, E. viridissimus, was significantly more frequent in the top layer of the moss, regardless of moisture condition. Migration within the moss cushion was not detected in any of these five species as a result of changes in moisture conditions. In xeric moss species, it may not be beneficial for tardigrades to migrate to avoid desiccation. Instead, they apparently undergo anhydrobiosis in both the top and bottom layers of the moss cushion.

Tardigrades of Louisiana and Arkansas, United States of America

The distribution of tardigrades in the states of the southern United States is poorly known. There are no published records from the state of Louisiana, while in Arkansas only one species has been reported. Samples of mosses and lichens from trees and rocks were collected from three sites in central and southern Louisiana and six sites in western Arkansas. Leaf litter samples were collected from one site in Louisiana. Nine species of tardigrade were found in Louisiana and 22 in Arkansas. The number of species per sample ranged from one to six.