An Evaluation of the Impact of Hiking Tourism on the Ecological Status of Alpine Lakes—A Case Study of the Valley of Dolina Pięciu Stawów Polskich in the Tatra Mountains

Anthropogenic pollution gradient along a mountain river affects bacterial community composition and genera with potential pathogenic species

Mountain regions in Poland are among the most frequently visited tourist destinations, causing a significant anthropogenic pressure put on the local rivers. In this study, based on numbers of 9 microorganisms, content of 17 antibiotics and 17 physicochemical parameters, we determined a pollution gradient in six sites along Białka, a typical mountain river in southern Poland. The E.coli/Staphylococcus ratio varied evidently between polluted and non-polluted sites, indicating that the possible utility of this parameter in assessing the anthropogenic impact on river ecosystems is worth further investigation. Then, using next generation sequencing, we assessed the changes in bacterial community structure and diversity as a response to the pollution gradient. Proteobacteria and Bacteroidetes were the most abundant phyla in the majority of samples. Actinobacteria were the most abundant in the most pristine (groundwater) sample, while Firmicutes and Verrucomicrobia were more prevalent in polluted sites. Bacterial diversity at various levels increased with water pollution. Eleven bacterial genera potentially containing pathogenic species were detected in the examined samples, among which Acinetobacter, Rhodococcus, and Mycobacterium were the most frequent. At the species level, Acinetobacter johnsonii was most prevalent potential pathogen, detected in all surface water samples, including the pristine ones. Two bacterial taxa-genus Flectobacillus and order Clostridiales showed very distinct variation in the relative abundance between the polluted and non-polluted sites, indicating their possible potential as biomarkers of anthropogenic impact on mountain river waters.

Exposure to global change pressures and potential impacts on ecosystem services of mountain lakes in the European Alps

Mountain lakes are increasingly affected by global change pressures. While there is growing evidence of impacts on ecosystem functioning, few studies considered changes in ecosystem services (ES). This study aimed (1) to examine the exposure of small and natural mountain lakes in the European Alps to global change pressures and (2) to estimate potential impacts on six relevant ES considering future climate projections and potential changes in water use. For 2455 lakes, we mapped the level of exposure to global change pressures, including climate change, atmospheric nutrient deposition, and anthropogenic activities (e.g., water use). Our results indicate that more than half of the Alpine mountain lakes feature a considerable level of exposure to global change. Hotspot analysis revealed spatial clusters of lakes with above-average exposure (23.7% of all lakes), mostly located in the central part of the Alps, while lakes with below-average exposure level prevailed in the south-western (19.3%) and eastern parts (10.6%). For 15 case study lakes, we quantified potential impacts on six key ES. The results revealed, in particular, potential negative effects on maintaining habitat and populations as well as aesthetic value, but contrastingly, also some positive effects for outdoor recreation, research and education. Our findings suggest the need for a comprehensive integration of mountain lakes into current management and policy frameworks to ensure the ecological integrity and ES provision of mountain lakes. Interdisciplinary mountain lake research will be important to overcome uncertainties related to the coupling of limnological parameters and ES indicators.

COVID-19 lockdown shows how much natural mountain regions are affected by heavy tourism

Mountain areas in Poland are among the most frequented tourist destinations and such intensive tourism negatively affects the natural environment. The COVID-19 pandemic and the resulting lockdown restricted travel for a few months in 2020, providing a unique opportunity to observe the studied mountain environment without the impact of typical tourist traffic. This study is based on the determination of antibiotic content, hydrochemical parameters, enumeration of culturable bacterial water quality indicators, antimicrobial susceptibility tests together with extended spectrum beta-lactamase (ESBL) gene detection in waterborne E. coli and NGS-based bacterial community composition at six sites along the Białka river valley (one of the most popular touristic regions in Poland) in three periods: in summer and winter tourist seasons and during the COVID-19 lockdown. The results of individual measurements showed decreased numbers of bacterial indicators of water contamination (e.g. numbers of E. coli dropped from 99 × 104 CFU/100 ml to 12 CFU/100 ml at the most contaminated site) and the share of antimicrobial resistant E. coli (total resistance dropped from 21% in summer to 9% during lockdown, share of multidrug resistant strains from 100 to 44%, and ESBL from 20% in summer to none during lockdown). Antibiotic concentrations were the highest during lockdown. The use of multivariate analysis (principal component analysis - PCA and heatmaps) revealed a clear pattern of tourism-related anthropogenic pressure on the water environment and positive impact of COVID-19 lockdown on water quality. PCA distinguished three major factors determining water quality: F1 shows strong effect of anthropogenic pressure; F2 describes the lockdown-related quality restoration processes; F3 is semi-natural and describes the differences between the most pristine and most anthropogenically-impacted waters.

Quantifying Ecosystem Services of High Mountain Lakes across Different Socio-Ecological Contexts

Mountain lakes are highly sensitive to global change, requiring sustainable management strategies that support crucial ecosystem services (ES). However, small mountain lakes are rarely in the focus of ES assessments, and indicators are potentially lacking. Therefore, this study aimed at comprehensively assessing key ES of 15 study lakes located in two regions in the European Alps. We involved local stakeholders and experts to identify important ES. We quantified eight ES in non-monetary terms, using 29 indicators based on limnological, spatial and socio-economic data. Finally, we evaluated ES in relation to the socio-ecological context of the study lakes. The most important ES included surface water for non-drinking purposes, maintaining populations and habitats, outdoor recreation, aesthetic value, entertainment and representation, scientific research, education as well as existence, option, or bequest value. Quantitative results indicate varying levels of ES across the study lakes. Based on 12 different socio-ecological variables, we identified four groups of lakes differing also in five ES. Maintaining populations and habitats, aesthetic value as well as existence, option or bequest value were rather independent from the socio-ecological context. Our findings contribute to a deeper understanding of ES of mountain lakes, also supporting the development of sustainable management strategies in mountain regions.

“A Gem among the Rocks”—Identifying and Measuring Visual Preferences for Mountain Lakes

The high visual quality of lakes bolsters aesthetic and recreational experiences, but little is known about the specific visual preferences related to mountain lakes. This study therefore aimed at assessing people’s preferences on visual characteristics of mountain lakes using an online questionnaire. Adopting a qualitative approach, we first identified major recognised characteristics of mountain lakes, i.e., respondents indicated that mountain lakes are typically small-sized lakes with clear, cold and blue water and are embedded in a natural mountain landscape. Then, we used different picture sets related to water clarity, water colour, presence of algae, lake shore and surrounding land cover to quantify preferences. Our results indicated a clear preference for blue, clear water and the absence of algae as well as large rocks at the lake shore and forest around the lake. In particular, preferences related to visual water characteristics were highly homogeneous across socio-cultural groups and confirmed previous findings. To illustrate the applicability of our findings, we integrated our results with spatial and limnological data to quantify aesthetic values for four selected study lakes in the European Alps. Finally, we discuss our findings in the context of increasing demand for nature-based experiences and the implications for decision-making.

Anthropogenic Impacts on Water Quality in a Small, Forested Mountain Catchment: A Case Study of the Seebächle, Black Forest, Southern Germany

The aims of this case study are to assess water quality in a small, forested mountain catchment in the Black Forest, forming part of a National Park and Natura 2000 zone. Field work was carried out in the catchment of the Seebächle torrent, a small headwater basin of the River Acher, a confluent of the Rhine, in Southern Germany between late winter and early summer of 2018. The catchment has a diverse natural setting of water bodies, including springs, torrents, and a lake, and is impacted by anthropogenic activities such as summer tourism, winter sports, two quarries, road traffic, and an isolated construction site. Physio-chemical and bacterial water samples were obtained at 10 measurement sites, including a spring, a lake (Mummelsee), a fountain, artificial and natural snow on and next to a ski run (Seibelseckle), artificial ditches and parking lots draining the ski run, and the Seebächle torrent above two granite mines. Samples were either taken directly on site or analyzed in corresponding hydrology and hospital microbiology laboratories. Water of the Seebächle is oxygen-rich, peaty, and mostly acidic, but the pH varies between 4.1 and 9.5 throughout the catchment, inclining towards acid in the fountain and below the ski run and towards alkaline in the lake. Conductivity is spatially highly variable, reaching the most elevated values below the ski run and its parking lot (149 µS/cm). A high density of bacteria including enterobacteria was detected at nearly all sites. Human pathogenic bacteria were found below and surrounding the ski run, at parking lots draining the ski run, as well as at the lowest site during the mid-spring campaign. They were also detected in the touristically highly frequented lake and in the spring feeding the lake during the end-of-spring campaign. Whilst most physico-chemical parameters followed a similar pattern and fell within good to very good EU drinking water quality status, the lake turbidity levels (19.2 NTU) by far exceeded norms after ice thawing. The most contaminated site in terms of bacteria and turbidity (5.2 NTU), ammonium nitrogen (0.18 mg/L), and total nitrogen (5.06 mg/L) was the spring feeding the Mummelsee draining the construction site of a new restaurant. These field analyses show that the water quality of a virtually uninhabited, natural headwater catchment is strongly interconnected and can degrade both by direct and indirect impacts of overtourism.