Data and code from: Between mosses and microbes: stable isotopes (¹⁵N, ¹³C) clarify the trophic niches of oribatid mites on a high-arctic permafrost archipelago (Svalbard, Norway)

Maraun, Mark 1 ; Clausen Kaiser, Rasmus1; Coulosn, Stephen2; Pan, Xue1; Scheu, Stefan 1 ; Seniczak, Anna3

Published Sep 15, 2026 on Dryad. https://doi.org/10.5061/dryad.69p8cz9jv

Abstract

Tundra biomes are strongly affected by globally changing temperatures. Rising temperatures will increase soil biota activity and result in higher CO₂ release from tundra soils and ‘greening’ of this biome, which in turn will affect carbon cycling and soil food webs. It is therefore important to better understand those high-latitude soil food webs in tundra biomes. Here, we investigated adult and juvenile soil living oribatid mites (Acari) in eight different microhabitats (i.e., patches of vegetation from Bistorta vivipara, Carex sp./Luzula sp., Cassiope tetragona, Dryas octopetala, Salix spp. and Saxifraga spp., mosses and grasses) using stable isotopes (¹⁵N, ¹³C) in the Svalbard archipelago, a challenging habitat for soil biota with permafrost soils being entirely frozen for about nine months of the year. Ten oribatid mite taxa were sufficiently abundant for stable isotope analyses, i.e., Camisia dictyna, Ceratoppia sphaerica, Diapterobates notatus, Dissorhina ornata, Fuscozetes setiger, Mycobates sarekensis, Oppiidae, Oribatula tibialis, Scutozetes arcticus and Tectocepheus sarekensis. Four trophic groups of oribatid mites were identified (phytophagous - likely feeding on mosses, secondary decomposers, predators/scavengers and lichen feeders); primary decomposers were missing, pointing to low litter quality. The “detrital shift” in ¹³C was generally low pointing to the dominance of young carbon resources including mosses. Most oribatid mite taxa (Camisia dictyna, Ceratoppia sphaerica, Diapterobates notatus, Fuscozetes setiger, Mycobates sarekensis and Scutozetes arcticus) were boreal/tundra habitat specialists with strong sclerotization which likely improves coping with cold and dry habitats. Juveniles and adults typically occupied the same trophic niche despite smaller body size and mouthparts than in adults. Oribatid mite trophic niches did not differ between microhabitats indicating that they are not specifically adapted to certain plant species or microhabitats. Overall, the consistent trophic roles of oribatid mites across microhabitats allows predicting how Arctic soil food webs will shift under continued warming. This repository makes available data and R Scripts for the associated study.

Dataset DOI: 10.5061/dryad.69p8cz9jv

Description of the data and file structure

The data attached here are the original stable isotope data of oribatid mites and microhabitats from Svalbard (Norway). Moreover, they include the calibrated (calibrated to litter) data for the statistical analysis. They also include the R Scripts for the statistical analyses of the data.

This repository contains the original data, R scripts, and supplementary material associated with this paper:
Authors: Mark Maraun, Rasmus Clausen Kaiser, Stephen J. Coulson, Xue Pan, Stefan Scheu, Anna Seniczak
Title: "Between mosses and microbes: stable isotopes (¹⁵N, ¹³C) clarify the trophic niches of oribatid mites on a high-arctic permafrost archipelago (Svalbard, Norway)"
Journal: Ecology and Evolution; doi: 10.5061/dryad.69p8cz9jv

Overview

This study investigated the trophic ecology of adult and juvenile soil living oribatid mites (Acari) in eight different microhabitats (i.e., patches of vegetation from Bistorta vivipara, Carex sp./Luzula sp., Cassiope tetragona, Dryas octopetala, Salix spp. and Saxifraga spp., mosses and grasses) using stable isotope ratios (15N/14N, 13C/12C) in the Svalbard archipelago. Ten oribatid mite taxa were sufficiently abundant for stable isotope analyses, i.e., Camisia dictyna, Ceratoppia sphaerica, Diapterobates notatus, Dissorhina ornata, Fuscozetes setiger, Mycobates sarekensis, Oppiidae, Oribatula tibialis, Scutozetes arcticus, and Tectocepheus sarekensis. Four trophic groups of oribatid mites were identified (phytophagous - likely feeding on mosses, secondary decomposers, predators/scavengers and lichen feeders); primary decomposers were missing, pointing to low litter quality. The “detrital shift” in Δ13C was generally low pointing to the dominance of young carbon resources including mosses. Most oribatid mite taxa (Camisia dictyna, Ceratoppia sphaerica, Diapterobates notatus, Fuscozetes setiger, Mycobates sarekensis, and Scutozetes arcticus) were boreal/tundra habitat specialists. Juveniles and adults typically occupied the same trophic niche despite smaller body size and mouthparts in juveniles than in adults. Oribatid mite trophic niches did not differ between microhabitats indicating that they are not specifically adapted to certain plant species or microhabitats.

Repository structure

000_README_Maraun_et_al_2026_Ecol_Evol_new.pdf– description of the repository
001_oribatid_mites_uncalibrated_data_new.csv – the uncalibrated stable isotope data
002_oribatid_mites_calibrated_data_new.csv – the litter calibrated stable isotope data
003_adults_and_juveniles_new.csv – the stable isotope data of juveniles and adults
004_microhabitats.csv – the stable isotope data of the mites in the microhabitats
004_R_Script_Camisia_juveniles_adults_new.R – the R script for analyzing juveniles and adults in Camisia
004_R_Script_Ceratoppia_juveniles_adults_new.R - the R script for analyzing juveniles and adults in Ceratoppia
004_R_Script_Diapterobates_juveniles_adults_new.R - the R script for analyzing juveniles and adults in Diapterobates
004_R_Script_Fusczetes_juveniles_adults_new.R - the R script for analyzing juveniles and adults in Fuscozetes
004_R_Script_Oribatula_juveniles_adults_new.R - the R script for analyzing juveniles and adults in Oribatula
004_R_Script_Tectocepheus_juvenils_adults_new.R - the R script for analyzing juveniles and adults in Tectocepheus
005_R_Script_microhabitats_new.R – the R script for analyzing stable isotopes of the mites in different microhabitats
006_Appendix_biogeography_figures_S1_-_S9.pdf – data on the biogeography of the studied oribatid mites – supplementary material
007_Appendix_statistics_new.pdf - summary of the statistical findings including figures - supplementary materia

These are the variables used in the files above:

For this file: 001_oribatid_mites_uncalibrated_data_new.csv

Species: the studied oribatid mite species (including all measurements)
Plant/litter: the baseline material for the stable isotope material
13C: the 13C signatures of the oribatid mites or the plant/litter material
15N: the 15N signatures of the oribatid mites or the plant/litter material
Species uncalibrated: the same species as above (just once mentioned since those data re the means and the standard deviation
Mean 13C: The mean of the 13C signatures of the oribatid mites or the plant/litter material
Std 13C: The standard deviation of the 13C signatures of the oribatid mites or the plant/litter material
Mean N15: The mean of the 15N signatures of the oribatid mites or the plant/litter material
Std N15: The standard deviation of the 15N signatures of the oribatid mites or the plant/litter material

For this file: 002_oribatid_mites_calibrated_data_new.csv

Species: the studied oribatid mite species
Number: the plot ID
Litter: the litter material
13C: the 13C signatures of the oribatid mites or the plant/litter material
N15: the 15N signatures of the oribatid mites or the plant/litter material
Calibrated 13C: the litter-calibrated 13C signatures of the oribatid mites
Calibrated 15N: the litter-calibrated 15N signatures of the oribatid mites
Animals uncalibrated: the names of the animals and the baseline data
Mean 13C: The mean of the 13C signatures of the oribatid mites or the plant/litter material
Std 13C: The standard deviation of the 13C signatures of the oribatid mites or the plant/litter material
Mean N15: The mean of the 15N signatures of the oribatid mites or the plant/litter material
Std N15: The standard deviation of the 15N signatures of the oribatid mites or the plant/litter material

For this file: 003_adults_and_juveniles_new.csv

Species: species names of the oribatid mites
Litter: the baseline material used for calibration
Calibrated 13C: the litter-calibrated 13C signatures of the oribatid mites
Calibrated 15N: the litter-calibrated 15N signatures of the oribatid mites

For this file: 004_microhabitats.csv

Nr: plot ID
Species: names of oribatid mite species
Litter: the baseline material
13C: the 13C signatures of the oribatid mites (uncalibrated)
N15: the 15N signatures of the oribatid mites (uncalibrated)

Requirements

Statistical analyses were performed using R version 4.5.3.

Reproducibility

The analyses can be reproduced by running the R scripts above

Data

The datasets required to reproduce the analyses are provided in the main directory

Results

The R scripts reproduce all analyses and figures presented in the article.

Contact

Mark Maraun, University of Göttingen, Faculty of Biology and Psychology, JFB Institute of Zoology and Anthropology, Untere Karspüle 2, 37073 Göttingen, Germany
email: mmaraun@gwdg.de
https://www.uni-goettingen.de/de/109123.html

Code/software

R and R Studio

Study sites, sampling and species determination

Samples including vegetation and soil, each 10 cm × 10 cm and 5 cm deep were cut using a knife at five sites in Ebbadalen in Svalbard (Norway) on July 7 2023. At each site three subsamples were taken from dominant plant microhabitats. Samples were kept cool (6 °C) at the University Centre in Svalbard (UNIS) until being taken to the University of Inland Norway where the oribatid mites were extracted using a Tullgren heat extractor for 10 days. Oribatid mite species which were relatively abundant in the samples and those which could be determined under the stereomicroscope were sorted and stored in 96 % ethanol for subsequent stable isotope analysis. The following species were included: adults and juveniles of Camisia dictyna, Ceratoppia sphaerica, Diapterobates notatus, Fuscozetes setiger, Tectocepheus sarekensis and Oribatula tibialis, and adults of Mycobates sarekensis, Oppiidae, Dissorhina ornate and Scutozetes arcticus. Soil and litter samples were taken from the following microhabitats at the five sampling sites if present: patches of (1) Bistorta vivipara, (2) Carex sp./Luzula sp., (3) Cassiope tetragona, (4) Dryas octopetala, (5) Salix spp., (6) Saxifraga spp., (7) grasses and (8) mosses.

Stable isotope analysis

Before stable isotope measurements, litter/plant, soil and animal samples were dried at 60 °C for 24 h. For each mite species between 5–10 individuals (depending on body mass) were transferred into tin capsules. We merged oribatid mites from litter and soil as stable isotope ratios of Oribatida species are consistent across soil layers (Lu et al. 2022). Litter and soil samples were ground in a ball mill (Retsch Mixer Mill MM200, Haan, Germany) and 1–2 mg was weighed into tin capsules. Animal, litter and soil samples were analyzed using a coupled system of an elemental analyzer (NA 1500, Carlo Erba, Milan, Italy) and a mass spectrometer (MAT 251, Finnigan, Bremen, Germany) adapted for the analysis of small sample sizes (Langel and Dyckmans, 2014). Ratios of the heavy isotope to the light isotope (¹³C/¹²C, ¹⁵N/¹⁴N, denoted as R) were expressed in parts per thousand relative to the standard using the delta notation with δ¹³C or δ¹⁵N = (R_sample/R_standard − 1) × 1000 (‰), with R_sample and R_standard being the respective target isotope ratios (¹⁵N/¹⁴N or ¹³C/¹²C). Vienna PD Belemnite limestone (V-PDB) and atmospheric nitrogen were used as standard for ¹³C and ¹⁵N, respectively. Acetanilide (C₈H₉NO, Merck, Darmstadt) was used for internal calibration (for details see Reineking et al. 1993).

Data analysis

For testing the first hypotheses, we calibrated animal stable isotope values to litter from the respective microhabitats as baseline (denoted as Δ¹³C and Δ¹⁵N values) (Klarner et al. 2014, Potapov et al. 2019) and aggregated them into four trophic groups (plant/moss feeders, primary decomposers, secondary decomposers/fungal feeders, predators/scavengers; Maraun et al. 2023). For testing the second hypothesis, we investigated the world-wide distribution of the studied oribatid mite species using data on the biogeography of oribatid mites (Xue Pan, unpubl. data; Global Oribatida Occurrence Data (GOOD)). For testing the third hypothesis, we compared Δ¹⁵N values of oribatid mite species for which we had juveniles and adults. For testing the fourth hypothesis, we compared the stable isotope values of all oribatid mites from the eight microhabitats with each other. All statistical analyses were done with linear mixed-effects model and subsamples nested in sites as random factors using the lme4, lmerTest and the emmeans packages in R (R Core Team 2025).

Data and code from: Between mosses and microbes: stable isotopes (15N, 13C) clarify the trophic niches of oribatid mites on a high-arctic permafrost archipelago (Svalbard, Norway)

Data files