Microplastics increase susceptibility of amphibian larvae to the chytrid fungus Batrachochytrium dendrobatidis.

Microplastics (MPs), a new class of pollutants that pose a threat to aquatic biodiversity, are of increasing global concern. In tandem, the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causing the disease chytridiomycosis is emerging worldwide as a major stressor to amphibians. We here assess whether synergies exist between this infectious disease and MP pollution by mimicking natural contact of a highly susceptible species (midwife toads, Alytes obstetricans) with a Bd-infected reservoir species (fire salamanders, Salamandra salamandra) in the presence and absence of MPs. We found that MP ingestion increases the burden of infection by Bd in a dose-dependent manner. However, MPs accumulated to a greater extent in amphibians that were not exposed to Bd, likely due to Bd-damaged tadpole mouthparts interfering with MP ingestion. Our experimental approach showed compelling interactions between two emergent processes, chytridiomycosis and MP pollution, necessitating further research into potential synergies between these biotic and abiotic threats to amphibians

Eradication of introduced fish allows successful recovery of a stream-dwelling amphibian

Introduction of alien fish is a major problem for the conservation of amphibians inhabiting originally fishless mountain streams. While fish eradication programs in lakes and ponds have proven successful for the recovery of amphibian populations, there is no such information for stream-dwelling amphibians, possibly because fish removal from streams is difficult and costly. Here, we show the first case of successful recovery of a stream-dwelling amphibian (Rana iberica) in a mountain area of central Spain, following eradication of introduced brook trout (Salvelinus fontinalis) and native brown trout (Salmo trutta) translocated from downstream reaches by local anglers. Electrofishing for 12 consecutive years eradicated both fish species in the introduced area, and allowed the recovery of the R. iberica population as a result of natural recolonization from nearby streams and reintroduction of captive-reared individuals. Our results demonstrate how electrofishing can be a costly but effective method for the eradication of introduced fish and the conservation of stream-dwelling amphibians

Habitat filtering determines spatial variation of macroinvertebrate community traits in northern headwater streams

Although our knowledge of the spatial distribution of stream organisms has been increasing rapidly in the last decades, there is still little consensus about trait-based variability of macroinvertebrate communities within and between catchments in near-pristine systems. Our aim was to examine the taxonomic and trait based stability vs. variability of stream macroinvertebrates in three high-latitude catchments in Finland. The collected taxa were assigned to unique trait combinations (UTCs) using biological traits. We found that only a single or a highly limited number of taxa formed a single UTC, suggesting a low degree of redundancy. Our analyses revealed significant differences in the environmental conditions of the streams among the three catchments. Linear models, rarefaction curves and beta-diversity measures showed that the catchments differed in both alpha and beta diversity. Taxon- and trait-based multivariate analyses also indicated that the three catchments were significantly different in terms of macroinvertebrate communities. All these findings suggest that habitat filtering, i.e., environmental differences among catchments, determines the variability of macroinvertebrate communities, thereby contributing to the significant biological differences among the catchments. The main implications of our study is that the sensitivity of trait-based analyses to natural environmental variation should be carefully incorporated in the assessment of environmental degradation, and that further studies are needed for a deeper understanding of trait-based community patterns across near-pristine streams

Quantifying the patient´s perspective in neuromyelitis optica spectrum disorder: Psychometric properties of the SymptoMScreen questionnaire

Background: The assessment of self-reported outcomes in neuromyelitis optica spectrum disorder (NMOSD) is limited by the lack of validated disease-specific measures. The SymptoMScreen (SyMS) is a patient-reported questionnaire for measuring symptom severity in different domains affected by multiple sclerosis (MS), but has not been thoroughly evaluated in NMOSD. The aim of this study was to assess the psychometric properties of the SyMS in a sample of patients with NMOSD. Methods: A non-interventional, cross-sectional study in adult subjects with NMOSD (Wingerchuk 2015 criteria) was conducted at 13 neuroimmunology clinics applying the SyMS. A non-parametric item response theory procedure, Mokken analysis, was performed to assess the underlying dimensional structure and scalability of items and overall questionnaire. All analyses were performed with R (v4.0.3) using the mokken library. Results: A total of 70 patients were studied (mean age: 47.5 ± 15 years, 80% female, mean Expanded Disability Status Scale score: 3.0 [interquartile range 1.5, 4.5]). Symptom severity was low (median SyMS score: 19.0 [interquartile range 10.0, 32.0]). The SyMS showed a robust internal reliability (Cronbach's alpha: 0.90 [95% confidence interval 0.86, 0.93]) and behaved as a unidimensional scale with all items showing scalability coefficients > 0.30. The overall SyMS scalability was 0.45 conforming to a medium scale according to Mokken's criteria. Fatigue and body pain were the domains with the highest scalability coefficients. The SyMS was associated with disability (rho: 0.586), and physical and psychological quality of life (rho: 0.856 and 0.696, respectively). Conclusions: The SyMS shows appropriate psychometric characteristics and may constitute a valuable and easy-to-implement option to measure symptom severity in patients with NMOSD

Perception of Stigma in Patients with Neuromyelitis Optica Spectrum Disorder

Background: Perception of stigma was associated with low self-esteem, psychological problems, and decreased health-seeking behavior among patients with different neurological disorders. The purpose of this study was to assess stigmatization and its impact in patients with neuromyelitis optica spectrum disorder (NMOSD). Methods: A non-interventional study was conducted at thirteen neuroimmunology clinics in Spain. Patients with a diagnosis of NMOSD (2015 Wingerchuk criteria) were included. The 8-item Stigma Scale for Chronic Illness (SSCI-8), the Expanded Disability Status Scale (EDSS), the 29-item Multiple Sclerosis Impact Scale (MSIS-29), the Beck Depression Inventory-Fast Screen (BDI-FS), the MOS Pain Effects Scale (MOS-PES) and the Fatigue Impact Scale for Daily Use (D-FIS) were used to assess the perception of stigma, disability, quality of life, mood, pain, and fatigue, respectively. Associations between outcome measures were analyzed using Spearman's rank correlation. Results: Seventy-one patients were studied (mean age: 47.4 years ± 14.9, 81.7% female, mean time since disease onset: 9.9 years ± 8.1). The median EDSS score was 3.0 (interquartile range 1.5, 4.5). Stigma prevalence was 61.4% (n=43). Thirty-one patients (43.6%) had depression. The SSCI-8 score showed a significant correlation with both physical (rho=0.576, p<0.0001) and psychological (rho=0.608, p<0.0001) MSIS-29 scales scores, EDSS score (rho=0.349, p=0.0033), BDI-FS score (rho= 0.613, p<0.0001), MOS-PES score (rho= 0.457, p<0.0001), and D-FIS score (rho=0.556, p<0.0001). Conclusion: Stigma is a common phenomenon affecting over 6 out of 10 patients with NMOSD. Understanding stigma may be useful to develop educational strategies improving NMOSD knowledge

Cognitive Performance and Health-Related Quality of Life in Patients with Neuromyelitis Optica Spectrum Disorder

Background: The frequency of cognitive impairment (CI) reported in neuromyelitis optica spectrum disorder (NMOSD) is highly variable, and its relationship with demographic and clinical characteristics is poorly understood. We aimed to describe the cognitive profile of NMOSD patients, and to analyse the cognitive differences according to their serostatus; furthermore, we aimed to assess the relationship between cognition, demographic and clinical characteristics, and other aspects linked to health-related quality of life (HRQoL). Methods: This cross-sectional study included 41 patients (median age, 44 years; 85% women) from 13 Spanish centres. Demographic and clinical characteristics were collected along with a cognitive z-score (Rao's Battery) and HRQoL patient-centred measures, and their relationship was explored using linear regression. We used the Akaike information criterion to model which characteristics were associated with cognition. Results: Fourteen patients (34%) had CI, and the most affected cognitive domain was visual memory. Cognition was similar in AQP4-IgG-positive and -negative patients. Gender, mood, fatigue, satisfaction with life, and perception of stigma were associated with cognitive performance (adjusted R-2 = 0.396, p < 0.001). Conclusions: The results highlight the presence of CI and its impact on HRQoL in NMOSD patients. Cognitive and psychological assessments may be crucial to achieve a holistic approach in patient care

Simulating Food Web Dynamics along a Gradient: Quantifying Human Influence

Realistically parameterized and dynamically simulated food-webs are useful tool to explore the importance of the functional diversity of ecosystems, and in particular relations between the dynamics of species and the whole community. We present a stochastic dynamical food web simulation for the Kelian River (Borneo). The food web was constructed for six different locations, arrayed along a gradient of increasing human perturbation (mostly resulting from gold mining activities) along the river. Along the river, the relative importance of grazers, filterers and shredders decreases with increasing disturbance downstream, while predators become more dominant in governing eco-dynamics. Human activity led to increased turbidity and sedimentation which adversely impacts primary productivity. Since the main difference between the study sites was not the composition of the food webs (structure is quite similar) but the strengths of interactions and the abundance of the trophic groups, a dynamical simulation approach seemed to be useful to better explain human influence. In the pristine river (study site 1), when comparing a structural version of our model with the dynamical model we found that structurally central groups such as omnivores and carnivores were not the most important ones dynamically. Instead, primary consumers such as invertebrate grazers and shredders generated a greater dynamical response. Based on the dynamically most important groups, bottom-up control is replaced by the predominant top-down control regime as distance downstream and human disturbance increased. An important finding, potentially explaining the poor structure to dynamics relationship, is that indirect effects are at least as important as direct ones during the simulations. We suggest that our approach and this simulation framework could serve systems-based conservation efforts. Quantitative indicators on the relative importance of trophic groups and the mechanistic modeling of eco-dynamics could greatly contribute to understanding various aspects of functional diversity

Relative influence of shredders and fungi on leaf litter decomposition along a river altitudinal gradient

We compared autumn decomposition rates of European alder leaves at four sites along the Lasset–Hers River system, southern France, to test whether changes in litter decomposition rates from upstream (1,300 m elevation) to downstream (690 m) could be attributed to temperature-driven differences in microbial growth, shredder activity, or composition of the shredder community. Alder leaves lost 75–87% of original mass in 57 days, of which 46–67% could be attributed to microbial metabolism and 8–29% to shredder activity, with no trend along the river. Mass loss rates in both fine-mesh (excluding shredders) and coarse-mesh (including shredders) bags were faster at warm, downstream sites (mean daily temperature 7–8°C) than upstream (mean 1–2°C), but the differ- ence disappeared when rates were expressed in heat units to remove the temperature effect. Mycelial biomass did not correlate with mass loss rates. Faster mass loss rates upstream, after temperature correction, evidently arise from more efficient shredding by Nemourid stoneflies than by the Leuctra-dominated assemblage downstream. The influence of water temperature on decomposition rate is therefore expressed both directly, through microbial metabolism, and indirectly, through the structure of shredder commu- nities. These influences are evident even in cold water where temperature variation is small

Benthic community structure and ecosystem functions in above- and below-waterfall pools in Borneo

Waterfalls are geomorphic features that often partition streams into discrete zones. Our study examined aquatic communities, litter decomposition and periphyton growth rates for above- and below-waterfall pools in Ulu Temburong National Park, Brunei. We observed higher fish densities in below-waterfall pools (0.24 fish m−2 vs. 0.02 fish m−2 in above-waterfall pools) and higher shrimp abundance in above-waterfall pools (eight shrimp/pool vs. less than one shrimp/pool in below-waterfall pools). However, macroinvertebrate densities (excluding shrimp) were similar among both pool types. Ambient periphyton was higher in below-waterfall pools in 2013 (4.3 vs. 2.8 g m−2 in above-waterfall pools) and 2014 (4.8 vs. 3.4 g m−2 in above-waterfall pools), while periphyton growth rates varied from 0.05 to 0.26 g m−2 days−1 and were significantly higher in below-waterfall pools in 2014. Leaf litter decomposition rates (0.001 to 0.024 days−1) did not differ between pool types, suggesting that neither shrimp nor fish densities had consistent impacts on this ecosystem function. Regardless, this research demonstrates the varied effects of biotic and abiotic factors on community structure and ecosystem function. Our results have highlighted the importance of discontinuities, such as waterfalls, in tropical streams.</p