Active dispersal of oribatid mites into young soils Lehmitz, Ricarda; Russell, David; Hohberg, Karin ...
Applied soil ecology : a section of Agriculture, ecosystems & environment,
04/2012, Letnik:
55
Journal Article
Recenzirano
► Active dispersal of oribatid mites during colonization of young soils. ► Mini-pitfall- and minicontainer traps for above-ground- and below-ground dispersal. ► Active dispersal is an important ...dispersal mechanism. ► Dispersal rates and mechanisms are species specific. ► 26% of species combined active movement and passive wind-dispersal.
Soil organisms contribute considerably to soil formation, fertility and microstructure of young soils. Oribatid mites as a part of the soil mesofauna are able to colonize young soils within a few years, but little is known about their dispersal pathways. In particular, the role of active dispersal during the colonization of young soils is almost unknown. The aims of the present study were (1) to determine the distance of active above-ground dispersal by oribatid mites in bare test plots with pure substrate using mini-pitfall traps in different distances to the source substrate (meadow), (2) to determine active below-ground movement using minicontainer traps in different distances to the meadow, (3) to calculate species-specific dispersal rates, and (4) to compare the contribution of wind-dispersal (investigated in a former study) as well as active above- and below-ground movement to the species assemblage dispersing into the bare plots. The results demonstrate that active migration occurs both above- as well as below-ground. From 31 species in the adjacent meadow, 17 immigrated into the bare test plots. The number of specimens and species actively moving above-ground significantly decreased with increasing distance along the bare substrate. Dispersal rates were species specific and varied between 0.3 and 2.1cm/day. The number of specimens actively moving below-ground was low. However, relative to the low specimen number the number of species was high. Particularly members of the Suctobelbidae and Oppiidae actively moved into the bare plots below-ground. Dispersal mechanisms were found to be species specific, as about 32% of the registered species moved actively below-ground, 32% moved actively above-ground and about 26% combined active movement and passive wind-dispersal. In conclusion, active dispersal is an important dispersal mechanism in the colonization of young soils. However, several species combine different dispersal mechanisms, so that the number of possible dispersal pathways is one factor that determines specimen- and species-richness in a newly found habitat.
Reliable and well-developed DNA barcode databases are indispensable for the identification of microscopic life. However, effectiveness of molecular barcoding in identifying terrestrial specimens, and ...nematodes in particular, has received little attention. In this study, ca 600 ribosomal large subunit DNA fragments (D3-D5 region) were successfully amplified for 79 limnic and terrestrial nematode species sampled at 147 locations across Germany. Distinctive DNA motifs in the LSU region were identified in 80% of all species examined. For 13 supposedly single morphospecies, 2-7 LSU barcode groups were detected with a wide range of intraspecific variations (0.09-7.9%). This region seems to be more suitable for the assessment of limno-terrestrial nematode diversity than the frequently used mitochondrial gene COI, as amplification success of the latter fragment is low for several nematode species. Our reference database for nematodes may serve as a starting point for applied and fundamental studies for these ubiquitous, ecologically highly relevant, organisms.
Oribatid mites are important colonizers of young soils, but little is known about their immigration pathways. In this study, one often-stated hypothesis was tested quantitatively: that wind is an ...important dispersal pathway. The aim was (1) to detect wind dispersal in oribatid mites (using sticky traps at different heights above ground level) and to determine factors influencing wind dispersal, (2) to investigate whether oribatids can survive wind dispersal and immigrate by wind into young soils (using mini-pitfall traps in test plots with oribatid-free substrate, active immigration being prohibited) and (3) to find out whether those oribatids are able to colonize young soils (using soil cores from the test plots). The results demonstrate (1) that mainly arboreal oribatid species were dispersed by wind – even at 160m height – and can therefore be spread over large distances. Nevertheless, about 10% of the wind-dispersed oribatid mites belonged to species able to live in the soil and may therefore be potential colonizers of young soils. The number of specimen and species transported by wind was the highest close to the soil surface and the number of dispersed individuals was mainly influenced by seasonality and humidity. The results also suggest that the probability of a soil oribatid being dispersed by wind depends on its original microhabitat (tree habitats>soil surface>deeper soil layers) and its body weight. It was also shown that soil-dwelling oribatid mites survived wind dispersal and immigrated by wind into the test plots and that colonization of the test plots took at least 2 months longer than immigration. However, colonization success was low during the first 2 years of investigation and only Trichoribates incisellus was found several times in the nutrient-poor substrate. Therefore, wind dispersal is an important migration pathway, especially for arboreal oribatids. We suggest that immigration into young soils most likely occurs by repeated short-distance dispersal. Only some species are able to survive the hostile conditions of wind dispersal as well as of pioneer soils, but those that do are potentially the founders of new populations.
Although soil ecology has benefited from recent advances in describing the functional and trophic traits of soil organisms, data reuse for large-scale soil food-web reconstructions still faces ...challenges. These obstacles include: (1) most data on the trophic interactions and feeding behaviour of soil organisms being scattered across disparate repositories, without well-established standard for describing and structuring trophic datasets; (2) the existence of various competing terms, rather than consensus, to delineate feeding-related concepts such as diets, trophic groups, feeding processes, resource types, leading to ambiguities that hinder meaningful data integration from different studies; (3) considerable divergence in the trophic classification of numerous soil organisms, or even the lack of such classifications, leading to discrepancies in the resolution of reconstructed food webs and complicating the reuse and comparison of food-web models within synthetic studies. To address these issues, we introduce the Soil Food Web Ontology, a novel formal conceptual framework designed to foster agreement on the trophic ecology of soil organisms. This ontology represents a collaborative and ongoing endeavour aimed at establishing consensus and formal definitions for the array of concepts relevant to soil trophic ecology. Its primary objective is to enhance the accessibility, interpretation, combination, reuse, and automated processing of trophic data. By harmonising the terminology and fundamental principles of soil trophic ecology, we anticipate that the Soil Food Web Ontology will improve knowledge management within the field. It will help soil ecologists to better harness existing information regarding the feeding behaviours of soil organisms, facilitate more robust trophic classifications, streamline the reconstruction of soil food webs, and ultimately render food-web research more inclusive, reusable and reproducible.
•The Soil Food Web Ontology is a formal conceptual model of soil trophic ecology.•The SFWO defines over 500 concepts relevant to soil food-web research.•It makes trophic data easier to access, interpret, integrate, process and reuse.•As an ongoing and open process, anyone can contribute to the development of the SFWO.
As the most abundant animals on earth, nematodes are a dominant component of the soil community. They play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across ...landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns.
Mofette fields, i.e. geogenic, cold CO2-exhaling gas vents occurring naturally in regions of tectonic or volcanic disturbances provide an excellent opportunity to investigate long-term responses of ...the soil biota to increased CO2 concentrations. The upper centimeters of mofette soils present a small-scale mosaic of different CO2 and O2 concentrations: From up to 100% CO2 and 0% O2 around local degassing vents to ambient soil atmosphere (<2% CO2). The present field study investigated the influence of CO2 on the community structure of Collembola as representatives of the air-filled fraction of the pore system and of Nematoda as inhabitants of soil water films.
Canonical correspondence analyses revealed strong correlations between soil faunal communities and environmental measures, above all CO2 concentration, organic matter content and plant coverage. An increase in CO2 concentration was followed by a steady decline in collembolan and nematode species richness and collembolan densities, but below a threshold of 62% CO2 had no significant effect on overall nematode densities. Collembolans developed viable populations at up to 20% CO2, where some mofettophilous species had their highest densities and frequencies, but other more general species also occurred (66% of overall collembolan densities). Nematodes, on the other hand, maintained individual-rich populations at up to 62% CO2, but above 20% CO2 nematode communities consisted almost entirely (97.6%) of three mofettophilous species: one feeding on bacteria, one on fungi and one on plant roots. Likely a combination of active and passive life phases together with temporal and micro-scale changes in environmental conditions allows survival of few mofettophilous species under CO2 conditions too extreme for most other species. The finding that mofettophilous species maintained denser populations in high CO2 patches, with species optima between 3% and 40% CO2, indicates that they even profit from CO2 degassing, presumably via changes in food supply or due to the lack of competitors.
•We investigated soil faunal community structure of natural carbon dioxide springs.•Nematodes were found in soil patches ≤62% CO2 and collembolans ≤20% CO2.•Of the main environmental drivers CO2 acted as dynamic and pH as stable niche factor.•Between 20 and 62% CO2, soil faunal communities consisted of only 3 nematode species.•CO2-tolerant species profit possibly via altered food supply or lack of competitors.
Although molecular analyses have contributed to a better resolution of the animal tree of life, the phylogenetic position of tardigrades (water bears) is still controversial, as they have been united ...alternatively with nematodes, arthropods, onychophorans (velvet worms), or onychophorans plus arthropods. Depending on the hypothesis favoured, segmental ganglia in tardigrades and arthropods might either have evolved independently, or they might well be homologous, suggesting that they were either lost in onychophorans or are a synapomorphy of tardigrades and arthropods. To evaluate these alternatives, we analysed the organisation of the nervous system in three tardigrade species using antisera directed against tyrosinated and acetylated tubulin, the amine transmitter serotonin, and the invertebrate neuropeptides FMRFamide, allatostatin and perisulfakinin. In addition, we performed retrograde staining of nerves in the onychophoran Euperipatoides rowelli in order to compare the serial locations of motor neurons within the nervous system relative to the appendages they serve in arthropods, tardigrades and onychophorans.
Contrary to a previous report from a Macrobiotus species, our immunocytochemical and electron microscopic data revealed contralateral fibres and bundles of neurites in each trunk ganglion of three tardigrade species, including Macrobiotus cf. harmsworthi, Paramacrobiotus richtersi and Hypsibius dujardini. Moreover, we identified additional, extra-ganglionic commissures in the interpedal regions bridging the paired longitudinal connectives. Within the ganglia we found serially repeated sets of serotonin- and RFamid-like immunoreactive neurons. Furthermore, our data show that the trunk ganglia of tardigrades, which include the somata of motor neurons, are shifted anteriorly with respect to each corresponding leg pair, whereas no such shift is evident in the arrangement of motor neurons in the onychophoran nerve cords.
Taken together, these data reveal three major correspondences between the segmental ganglia of tardigrades and arthropods, including (i) contralateral projections and commissures in each ganglion, (ii) segmentally repeated sets of immunoreactive neurons, and (iii) an anteriorly shifted (parasegmental) position of ganglia. These correspondences support the homology of segmental ganglia in tardigrades and arthropods, suggesting that these structures were either lost in Onychophora or, alternatively, evolved in the tardigrade/arthropod lineage.
Highlights • Respiratory response to a combination of O2 deprivation & extreme CO2 were tested. • Adaptations of nematodes occurring in natural CO2 springs were compared. • Nematodes were able to ...respirate down to very low oxygen concentrations. • Species maintaining respiration during stress were better physiologically adapted. • More tolerant species may occupy ecological niches, where others cannot exist.
At the coal-mining site 'Chicken Creek' (Spremberg, Germany), primary succession of the soil tardigrade community was investigated over a period of 4years after initial soil deposition in 2005. ...During the first 2years of succession, tardigrades occurred only sporadically and in very small numbers. In October 2007, algal-feeding Apodibius confusus first appeared at the site with small-scale mass densities of up to 2281 individuals in only 10cm2 of top soil. A. confusus from then on dominated the soils (98% of overall tardigrade counts). From October 2007 to May 2009, its distribution changed from patchy to homogenously and its mean densities gradually increased to 328.7 thousand tardigrades m-2. In May 2009, A. confusus was present in 100% of the samples, while at the same time, new tardigrade species became established, the second frequent species being Hexapodibius cf. micronyx (3% of overall counts). With A. confusus and H. cf. micronyx, two tardigrades with reduced claws inhabit the 'Chicken Creek' sites: complete lack of claws in the genus Apodibius and 4th pair of claws missing in the genus Hexapodibius. The use of claws in the pore system of coarse soil substrates and the necessity to clarify the position of Apodibius and Hexapodibius in the system of Tardigrada is discussed. At the moment, we intend to culture A. confusus to observe its locomotion and to provide life history data and alternative food sources of the species.Original Abstract: Auf der Flaeche Huehnerwasser im Braunkohletagebau bei Spremberg (Deutschland) wurde die Primaersukzession der Bodentardigraden waehrend der ersten vier Jahre nach Schuettung der Flaeche in 2005 untersucht. In den ersten beiden Sukzessionsjahren kamen Tardigraden nur sporadisch und in kleinen Zahlen vor. Im Oktober 2007 erschien dann der Algenfresser Apodibius confusus auf der Flaeche mit punktuellen Massenvorkommen von bis zu 2281 Tieren in nur 10cm2 Schuettsubstrat. Von diesem Zeitpunkt an dominierte A. confusus die Schuettsubstrate (98% der Tardigradenabundanzen). Zwischen Oktober 2007 und Mai 2009 wandelte sich seine Verteilung von verstreut zu homogen, und seine mittleren Dichten nahmen graduell bis 328700 Individuenm-2 zu. Im Mai 2009 wurde A. confusus schlieslich in 100% der Proben nachgewiesen. Zur gleichen Zeit etablierten sich auf der Flaeche auch andere Tardigradenarten, wie zum Beispiel Hexapodibius cf. micronyx, mit 3% der Gesamtabundanz die zweithaeufigste Art. Mit A. confusus und H. cf. micronyx leben zwei Tardigradenarten im Schuettsubstrat Huehnerwasser, die eine Reduktion der Krallen aufweisen: der Gattung Apodibius fehlen die Krallen gaenzlich, der Gattung Hexapodibius fehlen Krallen am 4. Beinpaar. Die Nuetzlichkeit von Krallen im Porensystem grobsandiger Schuettsubstrate und die Notwendigkeit einer Klaerung der Position von Apodibius und Hexapodibius im System der Tardigraden werden diskutiert. Derzeit versuchen wir A. confusus in Kultur zu nehmen, um darueber hinaus seine Bewegungsablaeufe zu beobachten und Lebenszyklus und Nahrungsspektrum der Art zu untersuchen.
At the coal‐mining site ‘Chicken Creek’ (Spremberg, Germany), primary succession of the soil tardigrade community was investigated over a period of 4 years after initial soil deposition in 2005. ...During the first 2 years of succession, tardigrades occurred only sporadically and in very small numbers. In October 2007, algal‐feeding Apodibius confusus first appeared at the site with small‐scale mass densities of up to 2281 individuals in only 10 cm2 of top soil. A. confusus from then on dominated the soils (98% of overall tardigrade counts). From October 2007 to May 2009, its distribution changed from patchy to homogenously and its mean densities gradually increased to 328.7 thousand tardigrades m−2. In May 2009, A. confusus was present in 100% of the samples, while at the same time, new tardigrade species became established, the second frequent species being Hexapodibius cf. micronyx (3% of overall counts). With A. confusus and H. cf. micronyx, two tardigrades with reduced claws inhabit the ‘Chicken Creek’ sites: complete lack of claws in the genus Apodibius and 4th pair of claws missing in the genus Hexapodibius. The use of claws in the pore system of coarse soil substrates and the necessity to clarify the position of Apodibius and Hexapodibius in the system of Tardigrada is discussed. At the moment, we intend to culture A. confusus to observe its locomotion and to provide life history data and alternative food sources of the species.
Zusammenfassung
Auf der Fläche Hühnerwasser im Braunkohletagebau bei Spremberg (Deutschland) wurde die Primärsukzession der Bodentardigraden während der ersten vier Jahre nach Schüttung der Fläche in 2005 untersucht. In den ersten beiden Sukzessionsjahren kamen Tardigraden nur sporadisch und in kleinen Zahlen vor. Im Oktober 2007 erschien dann der Algenfresser Apodibius confusus auf der Fläche mit punktuellen Massenvorkommen von bis zu 2281 Tieren in nur 10 cm2 Schüttsubstrat. Von diesem Zeitpunkt an dominierte A. confusus die Schüttsubstrate (98% der Tardigradenabundanzen). Zwischen Oktober 2007 und Mai 2009 wandelte sich seine Verteilung von verstreut zu homogen, und seine mittleren Dichten nahmen graduell bis 328700 Individuen m−2 zu. Im Mai 2009 wurde A. confusus schließlich in 100% der Proben nachgewiesen. Zur gleichen Zeit etablierten sich auf der Fläche auch andere Tardigradenarten, wie zum Beispiel Hexapodibius cf. micronyx, mit 3% der Gesamtabundanz die zweithäufigste Art. Mit A. confusus und H. cf. micronyx leben zwei Tardigradenarten im Schüttsubstrat Hühnerwasser, die eine Reduktion der Krallen aufweisen: der Gattung Apodibius fehlen die Krallen gänzlich, der Gattung Hexapodibius fehlen Krallen am 4. Beinpaar. Die Nützlichkeit von Krallen im Porensystem grobsandiger Schüttsubstrate und die Notwendigkeit einer Klärung der Position von Apodibius und Hexapodibius im System der Tardigraden werden diskutiert. Derzeit versuchen wir A. confusus in Kultur zu nehmen, um darüber hinaus seine Bewegungsabläufe zu beobachten und Lebenszyklus und Nahrungsspektrum der Art zu untersuchen.
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