Dataset supporting the use of nematodes as bioindicators of polluted sediments

Schenk J, Höss S, Brinke M, Kleinbölting N, Brüchner-Hüttemann H, Traunspurger W. Dataset supporting the use of nematodes as bioindicators of polluted sediments. Data in Brief. 2020;32: 106087.We provide the dataset supporting the research article “Nematodes as bioindicators of polluted sediments using metabarcoding and microscopic taxonomy” [1]. Nematodes are frequently used as bioindicators and the NemaSPEAR[%] is an validated index that is originally based on morphological data. The index was compared to molecular sequence data for the 28S rDNA, 18S rDNA and COI gene for 7 locations. This dataset includes chemical analyses of the sediments for 33 different substances. The sequence data for OTU-based analyses for the 28S rDNA, 18S rDNA and COI gene is given, together with the read distribution during bioinformatics processing. We furthermore include alternative ASV data, based on a cluster-independent approach. The morphological data is presented, including the biomass for each species, as well as an overview about whether the species is represented in the NCBI database. Furthermore, rarefaction analysis is given for the morphological data, and furthermore NMDS plots for the species and genus level based on morphological and molecular data. The correlation between the mean PEC-Q and the NemaSPEAR[%] values is given in order to compare the efficiency of the index, based on morphological and molecular data

A semi-fluid gellan gum medium improves nematode toxicity testing

Brinke M, Heininger P, Traunspurger W. A semi-fluid gellan gum medium improves nematode toxicity testing. Ecotoxicology and Environmental Safety. 2011;74(7):1824-1831.This study examined an alternative test medium for nematodes that use gellan gum as the gelling agent instead of agar. The semi-fluid consistency of the gel-like component nematode growth gellan gum (CNGG) supports three-dimensional distribution of the nematodes and food bacteria, but still allows free movement of the former. Moreover, flexible preparation of the medium and easy recovery of the test organisms are possible. Here, the effects of the nematicides ivermectin (pharmaceutical) and aldicarb (pesticide) and of the metal cadmium on the growth and reproduction of the free-living nematodes Caenorhabditis elegans and Panagrolaimus cf. thienemanni were studied in CNGG media. Results were compared to those obtained with the standard liquid test media in order to evaluate the applicability of CNGG for nematode toxicity testing. The sensitivity of P. cf. thienemanni to all three substances was found to be higher than that of C. elegans, but both nematodes showed the highest sensitivity to ivermectin exposure. This raises concerns about the risk posed by the pharmaceutical to non-target nematodes. In contrast to ivermectin bioassays carried out in CNGG medium, those conducted in liquid medium resulted in wide-ranging variability between and within replicates. Thus, CNGG seems to be particularly valuable for testing hydrophobic substances with a high sorption affinity as it favors their sorption to food bacteria and minimizes contact with the surfaces of the test vessels. However, the medium was less suitable for deriving toxicity thresholds for cadmium and may likewise not be an appropriate choice for testing other metals. The medium introduced herein was shown to be appropriate for sublethal nematode toxicity testing and likely provides a convenient environment for testing other nematode species. Besides improved testing of hydrophobic substances, CNGG also offers advantages for long-term studies, such as full life-cycle experiments, in which fresh medium is regularly needed. Moreover it may be beneficial for testing other poorly soluble or insoluble substances, such as nanoparticles. (C) 2011 Elsevier Inc. All rights reserved

Life history traits of the free-living nematode, Plectus acuminatus Bastian, 1865, and responses to cadmium exposure

Kreuzinger B, Brinke M, Traunspurger W, Majdi N. Life history traits of the free-living nematode, Plectus acuminatus Bastian, 1865, and responses to cadmium exposure. NEMATOLOGY. 2017;19(6):645-654.Free-living nematodes are ubiquitous and play an essential role in ecosystems. However, little is known about their standard life history traits (LHTs), which limits their inclusion in estimations of energy flows and carrying capacities of ecosystems, as well as in modelling population-level responses to toxicants. Thus, we used the hanging-drop method to measure LHTs of Plectus acuminatus with and without exposure to cadmium (2 mg l(-1)). In controls, the mean lifespan was 68 days and the maximum 114 days. Individuals laid eggs on average 19 days after hatching, while production of offspring peaked at 37 days. Plectus acuminatus individuals were very fertile, producing on average 848 juveniles. Population growth rate of 0.19 was estimated for the control cohort leading to an average population doubling time of 3.65 days. Exposure to cadmium reduced mean lifespan by 62% and affected reproduction as only 22% of individuals produced offspring, leading to a total fertility rate 85% lower than in controls

Nematodes as bioindicators of polluted sediments using metabarcoding and microscopic taxonomy

Schenk J, Höss S, Brinke M, Kleinbölting N, Brüchner-Hüttemann H, Traunspurger W. Nematodes as bioindicators of polluted sediments using metabarcoding and microscopic taxonomy. Environment International. 2020;143: 105922.The use of bioindicator species is a widely applied approach to evaluate ecological conditions, and several indices have been designed for this purpose. To assess the impact of pollution, especially in sediments, a pollution-sensitive index based on nematodes, one of the most abundant and species-rich groups of metazoa, was developed. The NemaSPEAR[%] index in its original form relies on the morphological inspection of nematode species. The application of a morphologically based NemaSPEAR[%] at the genus-level was previously validated. The present study evaluated a NemaSPEAR[%] index based on metabarcoding of nematode communities and tested the potential of fragments from the 28S rDNA, 18S rDNA and cytochrome c oxidase subunit I (COI) genes. In general, molecular-based results tended to show a poorer condition than morphology-based results for the investigated sites. At the genus level, NemaSPEAR[%] values based on morphological data strongly correlated with those based on molecular data for both the 28S rDNA and the 18S rDNA gene fragments (R2 = 0.86 and R2 = 0.74, respectively). Within the dominant genera (>3%) identified by morphology, 68% were detected by at least one of the two ribosomal markers. At the species level, however, concordance was less pronounced, as there were several deviations of the molecular from the morphological data. These differences could mostly be attributed to shortcomings in the reference database used in the molecular-based assignments. Our pilot study shows that a molecularly based, genus-level NemaSPEAR[%] can be successfully applied to evaluate polluted sediment. Future studies need to validate this approach further, e.g. with bulk extractions of whole meiofaunal communities in order to circumvent time-consuming nematode isolation. Further database curation with abundant NemaSPEAR[%] species will also increase the applicability of this approach

Added value of the NemaSPEAR[%]-index to routinely used macrofauna-based indices for assessing the quality of freshwater sediments

Brüchner-Hüttemann H, Höss S, Ptatscheck C, Brinke M, Schenk J, Traunspurger W. Added value of the NemaSPEAR[%]-index to routinely used macrofauna-based indices for assessing the quality of freshwater sediments. Ecological Indicators. 2021;121: 107015.Assessments of the ecological status of freshwater ecosystems, such as mandated by the EU Water Framework Directive, are routinely conducted by monitoring macroinvertebrates. However, for the quality assessment of fine sediments, macroinvertebrates are of limited suitability. In such habitats they show a low species diversity and often low densities, whereas a more diverse meiofauna can be found. Among the meiofaunal groups in benthic habitats, nematodes are one of the most abundant and species-rich. Fine, cohesive sediments considerably contribute to many ecosystem services, but they are often hotspots of chemical contamination as well. In the present study, the added value of the recently developed and validated NemaSPEAR[%]-index was evaluated by directly comparing it to routinely used macrofauna-based indices. Macrofaunal and nematode communities were synchronously monitored at seven sites in six different streams. The results of a chemical analysis of sediment pollutants combined with sediment quality guidelines revealed widely diverging toxic potentials at the seven investigated locations. The seasonal robustness of the NemaSPEAR[%]-index compared with macrofauna-based indices was also determined, by additionally obtaining synchronous samples of macrofauna and nematodes over the course of one year at one of the seven sites, a reference stream with very low toxic potential. The NemaSPEAR[%] performed robustly despite seasonal variations in the nematode community in the sediment of the unpolluted stream. At the seven sampling sites, representing a pollution gradient, the Nem- aSPEAR[%]-index correlated well with the toxic potential of the sediments. By contrast, the macrofauna-based indices did not correlate significantly with either the toxic potential of the sediments or with the results of NemaSPEAR[%] at the seven sites. For many non– endobenthic macroinvertebrates, chemical exposure is mostly through the water phase, such that the toxic potential of the sediments will not necessarily be reflected directly by macrofaunal indices. Accordingly, identifying the stressors that contribute to degrading the ecological status of a water body requires the inclusion of methods that examine different types of stressors, targets, and exposure pathways. Our study shows that the NemaSPEAR[%]-index provides added value to routinely used macrofaunal- based indices

Assessing effects of the pharmaceutical ivermectin on meiobenthic communities using freshwater microcosms

Brinke M, Hoess S, Fink G, Ternes TA, Heininger P, Traunspurger W. Assessing effects of the pharmaceutical ivermectin on meiobenthic communities using freshwater microcosms. AQUATIC TOXICOLOGY. 2010;99(2):126-137.Ivermectin is a widely applied veterinary pharmaceutical that is highly toxic to several non-target organisms. So far, little is known about its impact on benthic freshwater species, although its rapid sorption to sediment particles and high persistence in aquatic sediments have raised concerns about the risk for benthic organisms. In the present study, indoor microcosms were used to assess the impact of ivermectin on freshwater meiobenthic communities over a period of 224 days. Microcosm sediments were directly spiked with ivermectin to achieve nominal concentrations of 0.9, 9, and 45 mu g kg(-1) dw. Initially measured ivermectin concentrations (day 0) were 0.6, 6.2, and 31 mu g kg(-1) dw. In addition to abundance of major meiobenthic organism groups, the nematode community was assessed on the species level, assuming a high risk for free-living nematodes due to their close phylogenetic relationship to the main target organisms of ivermectin, parasitic nematodes. Benthic microcrustaceans (cladocerans, ostracods) and nematodes showed the most sensitive response to ivermectin, while tardigrades profited from the presence of the pharmaceutical. The most pronounced effects on the meiofauna community composition occurred at the highest treatment level (31 mu g kg(-1) dw), leading to a no observed effect concentration (NOECcommunity) of 6.2 mu g kg(-1) dw. However, the nematode community was already seriously affected at a concentration of 6.2 mu g kg(-1) dw with two bacterivorous genera, Monhystera and Eumonhystera, being the most sensitive, whereas species of omnivorous genera (Tripyla, Tobrilus) increased in abundance after the application of ivermectin. Thus, a NOECcommunity of 0.6 mu g kg(-1) dw was derived for nematodes. Direct and indirect effects of ivermectin on meiobenthic communities could be demonstrated. The pharmaceutical is likely to pose a high risk, because its NOECs are close to predicted environmental concentrations (PECs) in sediments (0.45-2.17 mu g kg(-1) dw), resulting in worst case risk quotients (RQs) of 1.05-36.2. This observation lends support to efforts aimed at preventing the repeated entry of ivermectin in aquatic environments and thus its accumulation in sediments. Moreover, this study points out that model ecosystem studies should be part of environmental risk assessments (ERAs) of veterinary medicinal products (VMPs). (C) 2010 Elsevier B.V. All rights reserved

Using meiofauna to assess pollutants in freshwater sediments: A microcosm study with cadmium

Brinke M, Ristau K, Bergtold M, et al. Using meiofauna to assess pollutants in freshwater sediments: A microcosm study with cadmium. Environmental Toxicology and Chemistry. 2011;30(2):427-438.The direct and indirect effects of Cd on benthic communities were assessed in a freshwater microcosm study over a period of seven months (218 d). Cadmium was regarded as a model substance to evaluate the usefulness of small-scale laboratory microcosm with microscopic fauna. In particular, effects on the meiofauna community, an ecologically important but rather neglected benthic component, were investigated. In addition, some microfaunal parameters (protozoan abundance and microbial activity) were determined. The sediment was spiked with nominal Cd concentrations of 10, 100, and 1,000 mg/kg dry weight. Because of the strong binding of Cd to sediment particles, measured Cd pore-water concentrations never exceeded 129.5 +/- 40.7 mu g/L. At 1,000 mg/kg dry weight, the abundances of the two dominant meiofauna taxa, nematodes and oligochaetes, were significantly reduced throughout the present study. Regarding nematodes, species of bacterivorous taxa (Daptonema, Eumonhystera) decreased, whereas species of predacious and omnivorous taxa (Mononcluts, Dorylaimus, and Ironus) increased in dominance in microcosms of the highest Cd concentration. Transient effects on microfauna were observed, especially in the first half of the present study, with a reduction in microbial activity and protozoan abundance. However, in microcosms receiving the highest Cd concentration, the abundance of the flagellate Euglena mutabilis increased significantly toward the end of the present study. The results of the present study support the use of small-scale microcosms with natural meiofauna communities as a suitable tool to assess the impact of pollutants in freshwater sediments. Environ. Toxicol. Chem. 2011;30:427-438. (C) 2010 SETA

Large Scale Risks from Agricultural Pesticides in Small Streams

Small streams are important refuges for biodiversity. In agricultural areas, they may be at risk from pesticide pollution. However, most related studies have been limited to a few streams on the regional level, hampering extrapolation to larger scales. We quantified risks as exceedances of regulatory acceptable concentrations (RACs) and used German monitoring data to quantify the drivers thereof and to assess current risks in small streams on a large scale. The data set was comprised of 1 766 104 measurements of 478 pesticides (including metabolites) related to 24 743 samples from 2301 sampling sites. We investigated the influence of agricultural land use, catchment size, as well as precipitation and seasonal dynamics on pesticide risk taking also concentrations below the limit of quantification into account. The exceedances of risk thresholds dropped 3.7-fold at sites with no agriculture. Precipitation increased detection probability by 43%, and concentrations were the highest from April to June. Overall, this indicates that agricultural land use is a major contributor of pesticides in streams. RACs were exceeded in 26% of streams, with the highest exceedances found for neonicotinoid insecticides. We conclude that pesticides from agricultural land use are a major threat to small streams and their biodiversity. To reflect peak concentrations, current pesticide monitoring needs refinement

Rating the risks of anticoagulant rodenticides in the aquatic environment: a review

Anticoagulant rodenticides are used worldwide to control commensal rodents for hygienic and public health reasons. As anticoagulants act on all vertebrates, risk is high for unintentional poisoning of terrestrial and aquatic wildlife. Causative associations have been demonstrated for the unintended poisoning of terrestrial nontarget organisms. However, behavior and fate of anticoagulant rodenticides in the aquatic environment have received minimal attention in the past despite considerable acute toxicity of several anticoagulants to aquatic species such as fish. In light of recent regulatory developments in the European Union concerning rodenticides, we critically review available information on the environmental occurrence, fate, and impact of anticoagulant rodenticides in the aquatic environment and identify potential risks and routes of exposure as well as further research needs. Recent findings of anticoagulant rodenticides in raw and treated wastewater, sewage sludge, estuarine sediments, suspended particulate matter, and liver tissue of freshwater fish in the low ng/L and µg/kg range, respectively, demonstrate that the aquatic environment experiences a greater risk of anticoagulant rodenticide exposure than previously thought. While the anticoagulant’s mechanism of action from the molecular through cellular levels is well understood, substantial data gaps exist regarding the understanding of exposure pathways and potential adverse effects of chronic exposure with multiple active ingredients. Anticoagulants accumulating in aquatic wildlife are likely to be transferred in the food chain, causing potentially serious consequences for the health of wildlife and humans alike