320 research outputs found
Data for: Less anxious salmon smolt become easy prey during downstream migration
No full textAntenna Readings for individual fishes. Also shown are positions of presumed predated fish detected using manually positionin
‐based community reconstruction
No full textAnalysis of environmental DNA detected in lake sediments shows promise to become a great paleoecological technique that can provide detailed information about organism communities living in past environments. However, when interpreting sedimentary environmental DNA records, it is of crucial importance to separate ecosystem responses to large-scale environmental change from “noise” caused by changes in sediment provenance or potential post-depositional DNA mobility. In this study, we show that plant and mammalian communities reconstructed from sediments are strongly affected by sediment provenance, but unaffected by vertical mobility of DNA after sediment deposition. We observe that DNA from aquatic plants was abundant in background sediment, while embedded detrital event layers (sediment deposited under erosion events) primarily contained terrestrial plants; hence, vertical mobility of aquatic plant DNA across sediment layers was negligible within our studied lakes. About 33% of the identified terrestrial plant genera were only found in detrital sediment, suggesting that sediment origin had a strong impact on the reconstructed plant community. Similarly, DNA of some mammalian taxa (Capra hircus, Ursus arctos, Lepus, and Felis) were only or preferentially found in detrital event layers. Temporal changes across the Holocene were the main drivers of change for reconstructed plant communities, but sediment type was the second most important factor of variance. Our results highlight that erosion and sediment provenance need to be considered when reconstructing past mammalian and plant communities using environmental DNA from lake sediments
The topological nature of tag jumping in environmental DNA metabarcoding studies
No full textMetabarcoding of environmental DNA constitutes a state-of-the-art tool for environmental studies. One fundamental principle implicit in most metabarcoding studies is that individual sample amplicons can still be identified after being pooled with others—based on their unique combinations of tags—during the so-called demultiplexing step that follows sequencing. Nevertheless, it has been recognized that tags can sometimes be changed (i.e., tag jumping), which ultimately leads to sample crosstalk. Here, using four DNA metabarcoding data sets derived from the analysis of soils and sediments, we show that tag jumping follows very specific and systematic patterns. Specifically, we find a strong correlation between the number of reads in blank samples and their topological position in the tag matrix (described by vertical and horizontal vectors). This observed spatial pattern of artefactual sequences could be explained by polymerase activity, which leads to the exchange of the 3′ tag of single stranded tagged sequences through the formation of heteroduplexes with mixed barcodes. Importantly, tag jumping substantially distorted our data sets—despite our use of methods suggested to minimize this error. We developed a topological model to estimate the noise based on the counts in our blanks, which suggested that 40%–80% of the taxa in our soil and sedimentary samples were likely false positives introduced through tag jumping. We highlight that the amount of false positive detections caused by tag jumping strongly biased our community analyses
Growth of plants on the Late Weichselian ice-sheet during Greenland interstadial-1?
No full textUnglaciated forelands and summits protruding from ice-sheets are commonly portrayed as areas where plants first establish at the end of glacial cycles. But is this prevailing view of ice-free refugia too simplistic? Here, we present findings suggesting that surface debris supported plant communities far beyond the rim of the Late Weichselian Ice-sheet during Greenland interstadial 1 (GI-1 or Bolling-Altered interstadial). We base our interpretations upon findings from terrigenous sediments largely resembling 'plant-trash' deposits in North America (known to form as vegetation established on stagnant ice became buried along with glacial debris during the deglaciation). In our studied deposit, we found macrofossils (N = 10) overlapping with the deglaciation period of the area (9.5-10 cal kyr BP) as well as samples (N = 2) with ages ranging between 12.9 and 13.3 cal kyr BP. The latter ages indicate growth of at least graminoids during the GI-1 interstadial when the site was near the geographic center of the degrading ice-sheet. We suggest that exposure of englacial material during GI-1 created patches of supraglacial debris capable of supporting vascular plants three millennia before deglaciation. The composition and resilience of this early plant community remain uncertain. Yet, the younger group of macrofossils, in combination with pollen and ancient DNA analyses of inclusions, imply that shrubs (Salix sp., Betula sp. and Ericaceae sp) and even tree species (Larix) were present in the debris during the final deglaciation stage. </p
jongmadrigal/SimVerde: SimVerde
No full textSimBasin - Participatory decision support system for the Verde River Basin in Mexico in the context of the Zapotillo conflict
Authors: Jonatan Godinez Madrigal, Joanne Craven and Pamela Claure Gutierrez. The user interface is based on SimBasin, available at: http://joannecraven.co.uk/projects/simbasin/. The water resources model is based on the model developed by UNOPS (2017) '14. Análisis de Escenarios de Modelación', in. UNOPS. Available at: http://201.131.6.193:8001/JaliscoSostenible/informe/.
Department of Land and Water Management, IHE Delft. Corresponding author: Jonatan Godinez Madrigal Contact information: [email protected]
El Tlacuache Núm. 667 (2015). 667 Año 13 (2015) marzo. El Tlacuache
No full textEl Vaso de la Ventilla: Nuevos datos para el
estudio del cuchillo curvo en Teotihuacan por Jaime Delgado Rubio, Norma, transgresión y sentencia en una población Nahua de la Huasteca por Jonatan Cerros C
El Tlacuache Núm. 693 (2015). 693 Año 13 (2015) septiembre. El Tlacuache
No full text¿El espacio, elemento del territorio? Multiespacialidad en tiempos de la multiterritorialidad por José Jonatan Cerros Chávez. - De minas, hidroeléctricas y santos. Territorialidad y percepciones en torno a la construcción de una planta hidroeléctrica en la Sierra Norte de Puebla por Claudia Guerrero Robledo
Drying by worming: deciphering how earthworms dry tundra soil
No full textDeep-burrowing earthworms (anecic and endogeic species) can dry soils by reworking mineral soil layers. Although this 'drying effect' has been reported across many ecosystems, including the Fennoscandian tundra, little is known about the driving processes. In this study, we measure plant transpiration in combination with controlled experiments of water holding capacity and evaporation to assess drivers of soil-water losses in tundra soil as the result of endogeic and anecic earthworms. Our experimental system was a common garden experiment with shrub-dominated (heath) and forb-dominated (meadow) vegetation (N = 48), where long-term monitoring revealed drier soils due to the addition of earthworms. Although we found that tundra plant transpiration was highest during the peak growing season and that meadow soil had a higher field capacity, our earthworm treatment did not strongly affect these two parameters. Evaporation, on the other hand, was on average 14 % higher in the meadow with earthworms although no such effect was observed in the heath soil. Using a network model of macropore vapor transfer that measures evaporation effects, we found an increase in macropore conductance between the subsoil and the atmosphere and that the vaporization rate in relation to the diffusion rate controls the strength of the evaporation effect. Our findings underscore the need to account for evaporation due to the reworking of pore architectures by soil biota when predicting changes in soil-water availability
Continuous measurement of red wood ant ( Formica rufa) outdoor behaviour using passive acoustic monitoring
No full textAnts serve as ecosystem engineers that maintain important ecological processes within forests. Given their ecological importance, it is a clear scientific shortcoming that we lack non-invasive methods to survey their behaviour inside common opaque habitats such as mounds, litter, and soil. In this study, we assess if acoustic signals from red wood ant ( Formica rufa) mounds are useful to infer temporal changes in ant activity within forested ecosystems. We found that acoustic indices used previously as a proxy for soil fauna in soil ecological studies (Acoustic Complexity Index, Bioacoustic Index) can indeed separate sounds generated by the ant's daily routines (biophony) from other forest sounds. Yet, we also show that these indices are problematic proxies for soil diversity as they increase not only due to an increased number of species but also due to an increased number of the same species. Acoustic measures that incorporated the strength of acoustic signals, Average Power Density (APD) and Peak Power Density (PPD) also increased with increasing ant abundance and constituted the conceptually best proxy for ant activity. For example, the PPD could i) track diurnal changes in Formica rufa activity with a high temporal resolution (minutes) and ii) detect altered behavioural responses to temperature changes. We conclude that microphones detecting biophony can provide high-resolution information about in situ ant behaviours in forested ecosystems. Thus, passive acoustics monitoring offers a promising avenue as a non-invasive monitoring tool for soil macrofauna studies
Non-Native Earthworms Alter Carbon Sequestration in Arctic Tundra Ecosystems
No full textEarthworms, as detritivores, play a significant role in breaking down soil organic carbon (SOC). The introduction of non-native earthworms to arctic ecosystems has, therefore, raised concerns about the potential impact they may have on one of the world's largest SOC reservoirs. Earthworms could also have considerable effects on plant productivity, and the lack of experimental studies quantifying their impact on carbon (C) reservoirs in both soil and plants makes it difficult to predict the effect of earthworms on ecosystem C storage. Here we experimentally tested how earthworms known to be non-native to arctic ecosystems (Aporrectodea spp. and Lumbricus spp.) affect C reservoirs in soil and plants (above and belowground separately) in two common tundra vegetation types (heath and meadow). Earthworms lowered the mean SOC pool and substantially altered SOC quality in meadow soils by increasing the proportion of aromatic-C compounds. Simultaneously, earthworms increased the C pool stored in plant biomass, which counteracted earthworm-induced SOC losses in meadow ecosystems. A positive earthworm effect on belowground biomass in heath soil facilitated a net ecosystem uptake of similar to 0.84 kg C m-2 over the 4-year study period. The higher C uptake into plant biomass in the heath resulted in a notable increase of SOC but lower delta 13C values, likely because of recently captured C being sourced from roots or litter. Our observations of vegetation-specific feedbacks between plants, earthworms, and soils advance our understanding of non-native earthworms' impact on SOC dynamics and C budgets in high-latitude ecosystems
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