Stream macroinvertebrate communities in restored and impacted catchments respond differently to climate, land-use, and runoff over a decade

Identifying which environmental drivers underlie degradation and improvements of ecological communities is a fundamental goal of ecology. Achieving this goal is a challenge due to diverse trends in both environmental conditions and ecological communities across regions, and it is constrained by the lack of long-term parallel monitoring of environmental and community data needed to study causal relationships. Here, we identify key environmental drivers using a high-resolution environmental - ecological dataset, an ensemble of the Soil and Water Assessment Tool (SWAT+) model, and ecological models to investigate effects of climate, land-use, and runoff on the decadal trend (2012-2021) of stream macroinvertebrate communities in a restored urban catchment and an impacted catchment with mixed land-uses in Germany. The decadal trends showed decreased precipitation, increased temperature, and reduced anthropogenic land-uses, which led to opposing runoff trends - with decreased runoff in the restored catchment and increased runoff in the impacted catchment. The two catchments also varied in decadal trends of taxonomic and trait composition and metrics. The most significant improvements over time were recorded in communities of the restored catchment sites, which have become wastewater free since 2007 to 2009. Within the restored catchment sites, community metric trends were primarily explained by land-use and evaporation trends, while community composition trends were mostly associated with precipitation and runoff trends. Meanwhile, the communities in the impacted catchment did not undergo significant changes between 2012 and 2021, likely influenced by the effects of prolonged droughts following floods after 2018. The results of our study confirm the significance of restoration and land-use management in fostering long-term improvements in stream communities, while climate change remains a prodigious threat. The coupling of long-term biodiversity monitoring with concurrent sampling of relevant environmental drivers is critical for preventative and restorative management in ecology.

Differential associations of five riverine organism groups with multiple stressors

The decline of river and stream biodiversity results from multiple simultaneous occuring stressors, yet few studies explore responses explore responses across various taxonomic groups at the same locations. In this study, we address this shortcoming by using a coherent data set to study the association of nine commonly occurring stressors (five chemical, one morphological and three hydraulic) with five taxonomic groups (bacteria, fungi, diatoms, macro-invertebrates and fish). According to studies on single taxonomic groups, we hypothesise that gradients of chemical stressors structure community composition of all taxonomic groups, while gradients of hydraulic and morphological stressors are mainly related to larger organisms such as benthic macro-invertebrates and fish. Organisms were sampled over two years at 20 sites in two catchments: a recently restored urban lowland catchment (Boye) and a moderately disturbed rural mountainous catchment (Kinzig). Dissimilarity matrices were computed for each taxonomic group within a catchment. Taxonomic dissimilarities between sites were linked to stressor dissimilarities using multivariable Generalized Linear Mixed Models. Stressor gradients were longer in the Boye, but did in contrast to the Kinzig not cover low stress intensities. Accordingly, responses of the taxonomic groups were stronger in the Kinzig catchment than in the recently restored Boye catchment. The discrepancy between catchments underlines that associations to stressors strongly depend on which part of the stressor gradient is covered in a catchment. All taxonomic groups were related to conductivity. Bacteria, fungi and macro-invertebrates change with dissolved oxygen, and bacteria and fungi with total nitrogen. Morphological and hydraulic stressors had minor correlations with bacteria, fungi and diatoms, while macro-invertebrates were strongly related to fine sediment and discharge, and fish to high flow peaks. The results partly support our hypotheses about the differential associations of the different taxonomic groups with the stressors.

The recovery of European freshwater biodiversity has come to a halt

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss1. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity2. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity.

The Asymmetric Response Concept explains ecological consequences of multiple stressor exposure and release

Our capacity to predict trajectories of ecosystem degradation and recovery is limited, especially when impairments are caused by multiple stressors. Recovery may be fast or slow and either complete or partial, sometimes result in novel ecosystem states or even fail completely. Here, we introduce the Asymmetric Response Concept (ARC) that provides a basis for exploring and predicting the pace and magnitude of ecological responses to, and release from, multiple stressors. The ARC holds that three key mechanisms govern population, community and ecosystem trajectories. Stress tolerance is the main mechanism determining responses to increasing stressor intensity, whereas dispersal and biotic interactions predominantly govern responses to the release from stressors. The shifting importance of these mechanisms creates asymmetries between the ecological trajectories that follow increasing and decreasing stressor intensities. This recognition helps to understand multiple stressor impacts and to predict which measures will restore communities that are resistant to restoration.

Invasion impacts and dynamics of a European-wide introduced species

Globalization has led to the introduction of thousands of alien species worldwide. With growing impacts by invasive species, understanding the invasion process remains critical for predicting adverse effects and informing efficient management. Theoretically, invasion dynamics have been assumed to follow an "invasion curve" (S-shaped curve of available area invaded over time), but this dynamic has lacked empirical testing using large-scale data and neglects to consider invader abundances. We propose an "impact curve" describing the impacts generated by invasive species over time based on cumulative abundances. To test this curve's large-scale applicability, we used the data-rich New Zealand mud snail Potamopyrgus antipodarum, one of the most damaging freshwater invaders that has invaded almost all of Europe. Using long-term (1979-2020) abundance and environmental data collected across 306 European sites, we observed that P. antipodarum abundance generally increased through time, with slower population growth at higher latitudes and with lower runoff depth. Fifty-nine percent of these populations followed the impact curve, characterized by first occurrence, exponential growth, then long-term saturation. This behaviour is consistent with boom-bust dynamics, as saturation occurs due to a rapid decline in abundance over time. Across sites, we estimated that impact peaked approximately two decades after first detection, but the rate of progression along the invasion process was influenced by local abiotic conditions. The S-shaped impact curve may be common among many invasive species that undergo complex invasion dynamics. This provides a potentially unifying approach to advance understanding of large-scale invasion dynamics and could inform timely management actions to mitigate impacts on ecosystems and economies.

Climate model variability leads to uncertain predictions of the future abundance of stream macroinvertebrates

Climate change has the potential to alter the flow regimes of rivers and consequently affect the taxonomic and functional diversity of freshwater organisms. We modeled future flow regimes for the 2050 and 2090 time horizons and tested how flow regimes impact the abundance of 150 macroinvertebrate species and their functional trait compositions in one lowland river catchment (Treene) and one mountainous river catchment (Kinzig) in Europe. We used all 16 global circulation models (GCMs) and regional climate models (RCMs) of the CORDEX dataset under the RCP 8.5 scenario to calculate future river flows. The high variability in relative change of flow among the 16 climate models cascaded into the ecological models and resulted in substantially different predicted abundance values for single species. This variability also cascades into any subsequent analysis of taxonomic or functional freshwater biodiversity. Our results showed that flow alteration effects are different depending on the catchment and the underlying species pool. Documenting such uncertainties provides a basis for the further assessment of potential climate-change impacts on freshwater taxa distributions.

A high-resolution streamflow and hydrological metrics dataset for ecological modeling using a regression model

Hydrological variables are among the most influential when analyzing or modeling stream ecosystems. However, available hydrological data are often limited in their spatiotemporal scale and resolution for use in ecological applications such as predictive modeling of species distributions. To overcome this limitation, a regression model was applied to a 1 km gridded stream network of Germany to obtain estimated daily stream flow data (m³ s^-1) spanning 64 years (1950-2013). The data are used as input to calculate hydrological indices characterizing stream flow regimes. Both temporal and spatial validations were performed. In addition, GLMs using both the calculated and observed hydrological indices were compared, suggesting that the predicted flow data are adequate for use in predictive ecological models. Accordingly, we provide estimated stream flow as well as a set of 53 hydrological metrics at 1 km grid for the stream network of Germany. In addition, we provide an R script where the presented methodology is implemented, that uses globally available data and can be directly applied to any other geographical region.

Projected effects of Climate-change-induced flow alterations on stream macroinvertebrate abundances

Global change has the potential to affect river flow conditions which are fundamental determinants of physical habitats. Predictions of the effects of flow alterations on aquatic biota have mostly been assessed based on species ecological traits (e.g., current preferences), which are difficult to link to quantitative discharge data. Alternatively, we used empirically derived predictive relationships for species' response to flow to assess the effect of flow alterations due to climate change in two contrasting central European river catchments. Predictive relationships were set up for 294 individual species based on (1) abundance data from 223 sampling sites in the Kinzig lower-mountainous catchment and 67 sites in the Treene lowland catchment, and (2) flow conditions at these sites described by five flow metrics quantifying the duration, frequency, magnitude, timing and rate of flow events using present-day gauging data. Species' abundances were predicted for three periods: (1) baseline (1998-2017), (2) horizon 2050 (2046-2065) and (3) horizon 2090 (2080-2099) based on these empirical relationships and using high-resolution modeled discharge data for the present and future climate conditions. We compared the differences in predicted abundances among periods for individual species at each site, where the percent change served as a proxy to assess the potential species responses to flow alterations. Climate change was predicted to most strongly affect the low-flow conditions, leading to decreased abundances of species up to -42%. Finally combining the response of all species over all metrics indicated increasing overall species assemblage responses in 98% of the studied river reaches in both projected horizons and were significantly larger in the lower-mountainous Kinzig compared to the lowland Treene catchment. Such quantitative analyses of freshwater taxa responses to flow alterations provide valuable tools for predicting potential climate-change impacts on species abundances and can be applied to any stressor, species, or region.

Eco-hydrologic model cascades: Simulating land use and climate change impacts on hydrology, hydraulics and habitats for fish and macroinvertebrates

Climate and land use changes affect the hydro- and biosphere at different spatial scales. These changes alter hydrological processes at the catchment scale, which impact hydrodynamics and habitat conditions for biota at the river reach scale. In order to investigate the impact of large-scale changes on biota, a cascade of models at different scales is required. Using scenario simulations, the impact of climate and land use change can be compared along the model cascade. Such a cascade of consecutively coupled models was applied in this study. Discharge and water quality are predicted with a hydrological model at the catchment scale. The hydraulic flow conditions are predicted by hydrodynamic models. The habitat suitability under these hydraulic and water quality conditions is assessed based on habitat models for fish and macroinvertebrates. This modelling cascade was applied to predict and compare the impacts of climate- and land use changes at different scales to finally assess their effects on fish and macroinvertebrates. Model simulations revealed that magnitude and direction of change differed along the modelling cascade. Whilst the hydrological model predicted a relevant decrease of discharge due to climate change, the hydraulic conditions changed less. Generally, the habitat suitability for fish decreased but this was strongly species-specific and suitability even increased for some species. In contrast to climate change, the effect of land use change on discharge was negligible. However, land use change had a stronger impact on the modelled nitrate concentrations affecting the abundances of macroinvertebrates. The scenario simulations for the two organism groups illustrated that direction and intensity of changes in habitat suitability are highly species-dependent. Thus, a joined model analysis of different organism groups combined with the results of hydrological and hydrodynamic models is recommended to assess the impact of climate and land use changes on river ecosystems.

A Modelling Framework to Assess the Effect of Pressures on River Abiotic Habitat Conditions and Biota

River biota are affected by global reach-scale pressures, but most approaches for predicting biota of rivers focus on river reach or segment scale processes and habitats. Moreover, these approaches do not consider long-term morphological changes that affect habitat conditions. In this study, a modelling framework was further developed and tested to assess the effect of pressures at different spatial scales on reach-scale habitat conditions and biota. Ecohydrological and 1D hydrodynamic models were used to predict discharge and water quality at the catchment scale and the resulting water level at the downstream end of a study reach. Long-term reach morphology was modelled using empirical regime equations, meander migration and 2D morphodynamic models. The respective flow and substrate conditions in the study reach were predicted using a 2D hydrodynamic model, and the suitability of these habitats was assessed with novel habitat models. In addition, dispersal models for fish and macroinvertebrates were developed to assess the re-colonization potential and to finally compare habitat suitability and the availability / ability of species to colonize these habitats. Applicability was tested and model performance was assessed by comparing observed and predicted conditions in the lowland Treene River in northern Germany. Technically, it was possible to link the different models, but future applications would benefit from the development of open source software for all modelling steps to enable fully automated model runs. Future research needs concern the physical modelling of long-term morphodynamics, feedback of biota (e.g., macrophytes) on abiotic habitat conditions, species interactions, and empirical data on the hydraulic habitat suitability and dispersal abilities of macroinvertebrates. The modelling framework is flexible and allows for including additional models and investigating different research and management questions, e.g., in climate impact research as well as river restoration and management.

[Workplace Health Promotion in Small, Medium-Sized and Large Enterprises of the Health-Care Sector - Frequency, Reasons for the Company Management to Take Action and Barriers to Implementation]

PURPOSE

The aim of this study was to gain insight into worksite health promotion in small and medium-sized companies compared to large concerns in Middle Franconia. Action in worksite health promotion, obstacles and demand for networks for workplace health promotion were determined.

METHOD

A standardised telephone interview served for collecting data for this cross-sectional study. The interviewee was always the manager or their proxy. 106 companies were contacted. The results of this study were analysed via qualitative and quantitative methods in SPSS(®) 20.

RESULTS

It was possible to reach and interview 80 companies, a return rate of 75.5%. More than half the companies (68.8%) implemented at least one activity for worksite health promotion, especially ergonomic measures and measures to promote physical activity. Taking the size of the company into consideration when analysing the results, previous study results are confirmed. With an increasing size of the company, the relative frequency of measures for workplace health promotion rises. The motivation for worksite health promotion ranges from keeping the employees healthy (38.2%) to worksite health promotion as part of the business culture (9.1%). 81.1% of the companies consider their activity in worksite health promotion to be successful. Furthermore, 80.0% of the firms that implemented worksite health promotion were supported by a partner like a health insurance (43.2%). Those companies that did not implement any activities for worksite health promotion, state as a prime reason that they did not think about it as yet (44.0%). Besides, 44.0% of the companies without any worksite health promotion would like to implement measures. 65.5% of the companies that already took action in worksite health promotion and 56.0% of the companies that did not would like to cooperate with other firms in a network for workplace health promotion. Mutual exchange is the most important factor for them.

CONCLUSION

The results of this study show that almost half of the companies that did not implement measures for worksite health promotion as yet would like to take action in this regard. For a bigger establishment of worksite health promotion, networks are predestinated and are best accompanied and supported by external professionals like health insurances, mutual indemnity associations or universities.

[The MEmbeR Multicenter Study on medical-occupational rehabilitation]

INTRODUCTION

MEmbeR is a prospective multi-center study on medical-occupational rehabilitation in Germany.

METHODS

196 neurological, psychiatric, orthopaedic, and internal medicine patients from 21 rehabilitation centres all across Germany have been enrolled and followed-up for 2 years after discharge. Primary outcome parameter was defined as return to work. Further, the SF-12 and a Mini-ICF-Rating have been used.

RESULTS

Mean age was 34.1 (9.9) years, length of stay 150.0 (223.5) days. Prior to occupational rehabilitation, 69.9% were unable to work, 2 years after discharge only 5.6%. Rate of participants seeking a job was reduced from 19.7% to 3.1%. In summary, 78.1% returned to work. Employed participants were younger (32.8 [9.7] vs. 38.5 [9.4] years, p=0.001) and less disabled (Degree of Disablement [GdB]: 20.0 [31.2] vs. 36.1 [33.7], p<0.05).

CONCLUSION

The multicenter cohort study MEmbeR provides further knowledge about the outcome of medical-occupational rehabilitation in Germany.

[Which occupational groups in a hospital are particularly stressed?]

BACKGROUND AND OBJECTIVE

Increasing workload in health professionals and resulting health consequences have frequently been reported. We analysed the results from an employee attitude survey within a network of workplace health promotion and compared three occupational groups of a university hospital with two samples of employees of other industries.

METHOD

The survey was conducted in the years 2005, 2006 and 2007 using a standardized method, addressing 1748 employees of six companies. In order to compare specific occupational groups, both within the hospital and amongst different companies, five occupational groups were selected (medical profession, nursing service and administration of the hospital, academics of another company and employees of a financial service provider).

RESULTS

Some results were specific for an occupational group, such as lower back pain and skin diseases in nurses and exhaustion in clinicians. Regarding several items the responses of employees of the hospital's administration were similar to that of the medical professionals and differed significantly from the responses of administrative and related employees in other companies. Employees of all occupational groups of the hospital were often frustrated and felt their work was not appreciated. Frequent demands included improved work atmosphere, better appreciation of work and better information regarding innovations.

CONCLUSIONS

The analysis of standardized survey results specific for companies and occupational groups is an appropriate way to identify targets of health promotion. Constant over three surveys, again a high burden of stress was found in health care workers even affecting the administrative staff, regarding several work-related stress factors. According to our results activities to improve the working conditions in hospitals are urgently needed.

Efficacy of contrast-enhanced US versus CT or MRI for the therapeutic control of percutaneous radiofrequency ablation in the case of hepatic malignancies

PURPOSE

The goal of this study was to assess the informative value of contrast-enhanced ultrasound after radiofrequency ablation (RFA). Patients who had undergone RFA of malignant liver tumors were followed up with contrast-enhanced sonography (CEUS), computed tomography (CT) and/or magnetic resonance tomography (MRI), and the outcomes were compared.

MATERIALS AND METHODS

76 patients undergoing 194 RFAs for 118 hepatic neoplasms (n = 55 HCC, n = 63 metastases) in the course of a 7-year period were examined post-interventionally using CEUS and CT or MRI. During follow-up (gold standard of evaluation), contrast agent rim accumulations with a diameter greater than 5 mm and a growth rate of at least 25 % were counted as a recurrence.

RESULTS

CEUS-CT comparison group: A total of 65 scan pairs were compared. In 54 cases (83.1 %) the findings were the same with either method. In 7 cases (10.8 %) CEUS confirmed the correct diagnosis, and in 2 cases (3.1 %) only CT was correct. In 2 cases (3.1 %) both methods yielded incorrect results. Diagnostic accuracy (DA): CEUS 93.8 %, CT 86.2 %. CEUS-MRI comparison group: In 23 cases (88.5 %) of a total of 26 scan pairs, the findings were the same for both CEUS and MRI. In 3 discordant cases only CEUS confirmed the correct diagnosis (3 cases, 11.5 %). Diagnostic accuracy DA (n = 26): CEUS 100 %, MRI 88.4 %.

CONCLUSION

CEUS performs equally to CT and MRI in the follow-up of patients treated for liver tumors by RFA.

[Workplace health promotion in network structures - the Erlangen Model of "enterprises in motion"]

INTRODUCTION

Evidence-based health promotion and prevention are the only means to meet the future economic challenges in health care. Since preventive measures do not penetrate all strata of society alike, the workplace is a probable platform for health education and promotion. Against this background, the network of the 'Erlangen Model' attempts to include health promotion as an integral part of enterprise policy; the present paper evaluates preliminary results of this programme.

METHOD

Questionnaires and interviews were conducted among employees of 6 companies and authorities forming the network "Agitating Enterprises". A total of 1,748 subjects were included and answered questions about their professional and health-related situation, physical activities, and expectations in connection with the programme.

RESULTS

Almost half of the subjects (48%) had no intention to participate in one of the programme's courses. Most frequent mentioned reasons in favour of participation were the expectation of positive effects on general health (75%), well-being (78%), team work (32%) and enjoyment of sports (70%). Factor analysis extracted 5 dimensions of occupational burden out of over 50 items: "Co-operation with colleagues and superiors", "safety at work", "workflow organisation", "individual complaints" and "workplace design". Between participating companies the expression of these dimensions varied substantially; employees of the university hospital in general reported a higher-than-average burden. In contrast, differences regarding the health status, satisfaction with employment conditions and individual activity scores were minor.

CONCLUSION

Health promotion at the workplace is meaningful, especially for health-care employees. Differential analyses of reasons for non-participation may reveal starting points for an improvement of attendance in health-promotion programmes.

Ergonomics diagnosis components in rehabilitation: statistical evaluation of an assessment instrument

The current paper examines an assessment instrument used for combined medical and occupational rehabilitation (MOR) in a group of German hospitals. Patients with a history of musculo-skeletal disease make up a significant proportion of those undergoing rehabilitation. Scale and factor structures, discriminant factors and clustering procedures used in the Bavaria rehabilitation patient assessment method (BRPAM) are investigated in a cross-sectional study involving a sample of 800 patients. Although the results reveal good correlation between differences in the job demand/patient capability profiles and the typical stresses to which the relevant occupation is exposed, analyses also indicate that several factors and items are unstable. According to subjective assessment by the patients, the therapeutic objectives are fully attained in some 80% of cases. Discrepancies between job demands and patient capability revealed by the BRPAM yield pointers to choice of therapy and its chances of success, but these need to be examined in greater detail in long-term studies.

Comparison of the effects of sodium pentosanpolysulfate and unfractionated heparin on venous thrombosis; an experimental study in rats

Sodium pentosanpolysulfate (Fibrezym) and unfractionated heparin (Liquemin) had significant antithrombotic efficacy in rats. 1 mg/kg body weight (BW) FibrezymR had its maximal effect 2-4 hours after subcutaneous administration; 200 U/kg BW LiqueminR s.c. were most effective 4-6 hours after application. Both drugs caused frequent embolic break-offs of thrombi during the time periods of maximal antithrombotic efficiency.