Mountain Lakes Research Articles

Water quality management in a tropical karstic system influenced by land use in Chiapas, Mexico

Urbanization and agricultural activities are increasingly threatening karstic systems and the water resources they provide, which are crucial for the livelihood of rural communities. Over the past decade, the Río Grande de Comitán-Lagos de Montebello (RGC-LM) watershed in Chiapas, Mexico, has experienced significant deterioration in water quality. The objective of this study was to analyze the water quality dynamics within the RGC-LM watershed and their potential interaction with land use change. We conducted assessments of the physicochemical and microbiological parameters across the lotic and lentic systems within the watershed over eight monitoring campaigns (from 2013 to 2020). Cluster Analysis (CA) and Principal Component Analysis (PCA) statistical approaches were performed to identify the main drivers of surface water quality variability. This approach aims to enhance water quality assessments within environmental management strategies, with the goal of promoting sustainable land-use practices aimed at protecting and improving water resources within the watershed. Our findings indicate that there is a substantial difference between the upper and lower watershed water quality. The good water quality conditions observed in the higher altitude lakes (mountain lakes) can be attributed to favorable topographical features, specific land use patterns, and effective conservation measures. In contrast, the lotic system in the middle watershed and the lentic water bodies located at lower altitudes (plain lakes) exhibit signs of water quality degradation due to inefficient wastewater treatment and agricultural runoff. This study highlights the importance of implementing adequate environmental management strategies to address these water quality challenges effectively. Given the pressing issue of water quality degradation in karstic environments, we emphasize on the need for increased monitoring frequency of both physicochemical and microbiological parameters to capture seasonal variations and to further understand the vulnerability of water resources in karstic environments. Future assessment of nutrient concentrations, pesticide levels, and blue-green algae populations will also be crucial for evaluating the trophic state at a watershed scale.

Diatomite evidence for a small palaeo mountain lake at 3400 m asl, Lesotho, southern Africa

ABSTRACTThe Eastern Lesotho Highlands experience an excess of rainfall sufficient to form the country's primary export, supplying the economic hub of southern Africa, Gauteng South Africa. However, there is currently only one natural lake in the country, Letšeng‐la Letsie, and evidence of palaeolakes in the region is therefore of particular interest. This study presents the analysis of a diatomite outcrop from a depression northwest of Mafadi Summit, at 3400 m asl. The presence of diatomite, dominated by the facultative planktonic species Staurosirella pinnata and Staurosira construens and abundant planktonic Aulacoseira ambigua, is indicative of the continuous presence of a shallow lake between ~4600 and 100 cal a bp. Comparative analysis of rainfall for the Mafadi and Letšeng‐la Letsie regions from CHIRPS gridded rainfall data demonstrates sufficient rainfall for a lake of comparable size, if not larger, as Mafadi receives considerably more rainfall than Letšeng‐la Letsie. Analysis of the SRTM 30‐m Digital Elevation Model and Topographic Position Index calculations demonstrate the feasibility of a shallow surface water feature at Mafadi. The conversion of this palaeolake into the contemporary wetland is hypothesized to be the result of post‐industrial warming, possibly augmented by migration of livestock into the Eastern Lesotho Highlands.

Exploring the Spatiotemporal Evolution Patterns and Determinants of Construction Land in Mianning County on the Eastern Edge of the Qinghai–Tibet Plateau

Studying the spatiotemporal evolution and driving forces behind construction land amidst the intricate ecological and geological setting on the eastern edge of the Qinghai–Tibet Plateau offers invaluable insights for local sustainable development in a landscape transition zone and ecologically fragile area. Using construction land data from four phases, spanning 1990 to 2020, in Mianning County, this study employs methodologies like the Landscape Expansion Index (LEI) and land use transfer matrix to delineate the spatiotemporal evolution characteristics of construction land. A comprehensive set of 12 influencing factors across five categories—geomorphology, geological activity, climate, river and vegetation environment, and social economy—were examined. The Geographically Weighted Regression (GWR) model was then employed to decipher the spatial distribution pattern of construction land in 1990 and 2020, shedding light on the driving mechanisms behind its changes over the three decades. The research reveals distinct patterns of construction land distribution and evolution in Mianning County, shaped by the ecological and geological landscape. Notably, the Anning River wide valley exhibits a concentrated and contiguous development mode, while the Yalong River deep valley showcases a decentralized development pattern, and the Dadu River basin manifests an aggregation development mode centered around high mountain lakes. Over the study period, all three river basins witnessed varying degrees of construction land expansion, transitioning from quantitative expansion to qualitative enhancement. Edge expansion predominantly characterizes the expansion mode, complemented by leapfrog and infilling modes, accompanied by conversions from cropland and forest land to construction land. An analysis of the spatial pattern and drivers of construction land change highlights human-induced factors dominating the Anning River Basin, contrasting with natural factors prevailing in the Yalong River Basin and the Dadu River Basin. Future efforts should prioritize climate change considerations and environmental capacity, aiming for an ecologically resilient spatial pattern of construction land.

WITHDRAWN: Reconstructing the environmental impact of mining on mountain lakes

Mountain lakes are particularly fragile ecosystems undergoing important transformations associated with ongoing global change. However, the history of anthropogenic impacts on mountain lakes and their catchments is much longer, in many cases featuring millennia of summer pastoral farming. More recently, the growing demand for raw materials and energy linked to industrialization, particularly accelerated since the 19th century CE, meant a further increase in human impact on mountain areas. The Cantabrian Range (northern Spain) constitutes a paradigmatic case of southern European mountain range experiencing intense human impact during the past few millennia and particularly the past two centuries. Here, we have reconstructed the environmental dynamics of this area during the last millennium, with a particular focus on the impact of mining, based on the multidisciplinary analysis (sedimentology, biogeochemistry, magnetic susceptibility, diatoms, pollen, charcoal and dung fungal spores) of sediment cores from Lago de La Cueva (43°03′N, 6°06′W, 1550 m a.s.l.). Changing land use and climate have driven lake dynamics during the last centuries. A major fire-caused deforestation event dated to the late 15th century CE increased erosion and the frequency of intense runoff episodes, in the context of the wetter and colder Little Ice Age. The onset of iron mining activities in the catchment ca. 200 years ago had a strong impact on the lake. Sedimentation rates notably raised and mining waste containing hematite and potentially toxic elements (e.g. Fe, Co, As) was washed into the lake. Additionally, diatom assemblages showed that lake regulation since the early 20th century CE severely altered the natural hydrological regime introducing rapid seasonal lake-level oscillations and increased lakeshore erosion, water turbidity and nutrient loads. The recent environmental restoration, finished in 2006, has involved the re-deposition of large volumes of mine tailing. Although some mining wastewater still arrives into the lake because mine drainage is still active, restoration works have succeeded in reducing erosion rates and nutrient loads. Lower land-use intensity has also contributed to natural vegetation recovery, further diminishing erosion. This study illustrates the complex interactions between human activities (grazing, mining, hydropower) and climate change in defining mountain landscape shifts through time. Moreover, our results highlight the usefulness of paleolimnological research to quantitatively assess the effectiveness of lake restoration programs.

Evaluation of the Geotourism Potential of the Mountain Lakes in the Călimani Massif: Colibița Lake, Iezer Lake and Zânelor Lake

Evaluation of the Geotourism Potential of the Mountain Lakes in the Călimani Massif: Colibița Lake, Iezer Lake and Zânelor Lake. This paper evaluates the key geosites in the Călimani National Park: Colibița Lake, Iezer Lake and Zânelor Lake. The internationally recognized methodology used in this study has a crucial role in the development of tourism and the conservation of natural resources. The obtained results show that these geosites have a significant potential for tourism development. Colibița Lake, an artificial lake, attracts tourists with its picturesque landscape and recreational activities. Iezer Lake impresses with its natural beauty and ecological importance, being a crucial habitat for local flora and fauna. Zânelor Lake offers a unique cultural experience, thanks to the charming landscape and local legends. The evaluation and management of these geosites will contribute to the management and conservation of natural resources in the Călimani Massif. The development of sustainable tourism requires appropriate management strategies that ensure responsible use and conservation of the environment. Promoting sustainable tourism and respecting conservation principles will ensure the preservation and sustainable exploitation of these geosites, benefiting both local communities and visitors. Keywords: Geotourism, Geosite, Călimani Massif, Carpathian Mountains, Romania.

UAV-based LiDAR Bathymetry at an Alpine Mountain Lake

Abstract. LiDAR bathymetry provides an efficient and comprehensive way to capture the topography of water bodies in shallow water areas. However, the penetration depth of this measurement method into the water column is limited by the medium water and water turbidity, resulting in a limited detectability of the bottom topography in deeper waters. An increase of the analyzable water depth is possible by the use of extended evaluation methods, in detail full-waveform stacking methods. So far, however, this has only been investigated for water depths of up to 3.50 m due to water turbidity. In this article, the potential of these extended data processing methods is investigated on an alpine mountain lake with low water turbidity and thus high analyzable water depth. Compared to the standard data processing, the penetration depth could be significantly increased by 58%. In addition, methods for depth-resolved water turbidity parameter determination on the basis of LiDAR bathymetry data were successfully tested.

Estimating stream sediment loads to assess management options for a Southern Appalachian mountain lake

Enka Lake is a 25-ha reservoir in the Southern Appalachian mountains surrounded by the Biltmore Lake residential neighborhood. The aesthetic and recreational value of Enka Lake can be negatively affected by turbid water and sediment buildup, resulting from stormwater originating upstream in its 15.38 km2 watershed. In this study, we monitored streamflow and sediment loads for nearly 2 years to better understand sedimentation dynamics and evaluate management options. We collected nearly 500 water samples throughout the watershed, focusing on two tributaries that provide the majority of streamflow into Enka Lake. During baseflow conditions, those tributaries are very clear (turbidity ranging from 1 to 20 NTU), but sediment-laden stormflow (turbidity > 1000 NTU) from dirt roads, gravel driveways, and poorly vegetated yards is common and, during extreme storm events, causes lake discoloration. Discharge-sediment data pairs were used to construct sediment rating curves and estimate sediment fluxes through these tributaries. The predicted sediment fluxes were tested with high-frequency sampling during and after three storms in different seasons; predicted values underestimated the peak sediment fluxes (0–400%) but generally matched total measured sediment loads. Estimates of annual sediment load from the two tributaries (540–900 tonnes/year) suggest that a dredging effort commissioned by the neighborhood association in 2016 may have removed only about 1–3 years’ worth of sediment. Installing sediment forebays or other retention structures is likely the preferred sediment management strategy moving forward (over a regular dredging schedule) since they can be maintained more easily without affecting lake levels. Designing these retention structures will benefit from the estimates of stormflow and sediment fluxes, and the study design presented here—including the help of community-based volunteer samplers—provides a model that could be used at other sites in the Southern Appalachians and elsewhere.

Трансформація оселищ і її вплив на зообіоту

The history of the use of the term “habitat” is considered. It is emphasized that this term refers to the habitat of a particular animal species or population and is determined by their ranges. The factors that lead to the destruction of habitats of many populations on the lowlands and in the highlands of the Ukrainian Carpathians are indicated. Attention is drawn to the degradation of mountain lakes and streams as habitats for aquatic hydrobionts. Among the factors that cause the destruction of habitats, the factors of both natural and anthropogenic origin are identified: climate change, absolute protection of territories, demutational processes, uncontrolled recreation activities, changes in traditional land use, water chemiсal composition and pollution, the appearance of invasive plants, urbanization, etc. The synergistic effect of these factors leads to rapid habitat change, and thus to the loss of adaptive capacity of individuals of different species to the changed conditions of their habi­tats. Among the objects of our study are such taxa as planktonic crustaceans (Cladocera), ants (Formicidae), lampreys (Cyclostomata), ray-finned fish (Actinopterygii), amphibians (Amphibia) and birds (Aves). It was found, in particular, that deciduous forest habitats are the most favorable for the existence of a significant diversity of ants. The mega-habitats for amphibians were identified as a complex of individual habitats that vary during the vegetation season and are connected by migration routes. The key habitat in Western Polissia, as an example, can be the Unychi wetland, which is home to a number of rare bird species. The nest-building behavior of birds under the influence of anthropogenic factors also undergoes changes - its species-specific appearance and composition of nesting materials are transformed in response to habitat pollution. In addition, the study showed that the use of invasive trees and shrubs for urban greenery has a negative impact on the diversity of urban bird fauna, as it paradoxically reduces the number of nesting and foraging habitats for birds. It is proposed to identify key habitats for the populations of rare and endangered animal species within the protected areas and on the non-protected ones, to indicate their locations and the type of management approach (protection, restoration, reconstruction, etc.).

Environmental Factors Structuring Diatom Diversity of the Protected High Mountain Lakes in the Kaçkar Mountains National Park (Rize, Turkey)

The altitude of the habitat is one of the important regulators of species survival. Kaçkar Mountains National Park is located in the Eastern Black Sea region of Turkey. This is the first study on the benthic diatom flora of the high mountain lakes in Kaçkar Mountains National Park, which is situated between 2782 and 3075 m a.s.l. A total of 84 diatom species were identified from benthic communities of 15 habitats in summer (19 July, 28 August) and autumn (10 September) months of 2020. The genus Pinnularia (thirteen species) formed the basis of the taxonomic list, followed by Eunotia (five species), Navicula (five species), and Frustulia (four species) genera, respectively. The waters in all the studied lakes were fresh, low-saline, with low-alkaline or circumneutral pH and organically uncontaminated, as evidenced by prevailed bioindicator groups. Statistical methods and comparative floristic results confirm the role of the lake altitude for the diatom species distribution. The species richness of the studied lakes was higher in lakes with lower altitudes. The statistical approach also revealed the potential for an increase in the number of species in high mountain lakes if the study of the diatom flora of the Kachkar Mountains National Park is continued and the species composition of the lakes is replenished. Further studies will be needed to continue exploring this pattern. To protect studied high mountain lakes, their ecological conditions must be constantly monitored in the Kaçkar Mountains National Park.

Ice phenology interactions with water and air temperatures in high mountain lakes

Ice phenology is of great importance for the thermal structure of lakes and ponds and the biology of lake species. Under the current climate change conditions, ice-cover duration has been reduced by an advance in ice-off, and a delay in ice-on, and future projections foresee this trend as continuing. Here, we describe the current ice phenology of Pyrenean high mountain lakes and ponds, including ice-cover duration and ice-on and ice-off dates. We used mixed models to identify the variables that explained the observed patterns, extrapolated them across all water bodies in the mountain range, and related the seasonality of air and water temperatures with ice phenology using structural equation models. Ice phenology was obtained from the temperature series of 85 lakes and ponds for fourteen years, including 2001 to 2004 and 2009 to 2019. We discovered that high autumn precipitation was related to earlier ice-on dates, and that earlier ice-off dates were associated with higher following-summer water temperatures. We found a greater predictability of ice-off dates and ice-cover duration than ice-on dates. Altitude was the most important variable explaining the variation in ice phenology, followed by latitude, which was related to climatic differences among the northern and southern slopes of the mountain range. The lake area was significant for ice-on dates and ice-cover duration. The interannual variability in air temperature and radiation was remarkable for the ice-off date and ice-cover duration but not for the ice-on date. In contrast, wind speed was related to an earlier ice-off date and shorter ice-cover duration. All the measured lakes and ponds froze in winter during the studied period, a feature maintained in the extrapolation to the whole set of water bodies.

A long-term study of the impact of the invasive species Eurasian minnow Phoxinus phoxinus on brown trout Salmo trutta production in a high mountain lake, Southern Norway

The shallow Lake Skjerja was originally one of the most outstanding brown trout lakes on the Hardangervidda mountain plateau. During the period 1973–1985, the annual yield was on average 3.35 kg ha-1. In the mid-1980s, Eurasian minnow established a dense population in the lake. Since 1994, 5304 kg of Eurasian minnow have been removed with baited traps, which correspond to an annual mean catch of 177 kg year-1 or 1.12 kg ha-1. The competition for food, in addition to longer food chains, has had a strong negative impact on the brown trout production, with an annual yield reduced to 1.07 kg ha-1, or 32% of the historical catches (1973-1985). The total removed biomass of the two fish species correspond to 65% of the brown trout yield before the invasion of the Eurasian minnow. In Lake Skjerja, the two crustacean species Gammarus lacustris and Lepidurus arcticus, have historically been staple food items for brown trout. Fishing with baited traps on the minnows, and the presence of a large fraction of predatory brown trout, may have reduced the predation pressure on the two crustacean species, and they are still a part ofthe brown trout diet. The availability of fish as food has resulted in a significant increase in the presence of large individuals of brown trout with maximum weights above four kg. Despite reduced annual yield of brown trout, Lake Skjerja is still a popular fish destination with nearly 200 big-sized brown trout (mean annual weight 1065 grams) landed annually. On Hardangervidda, an increase in air temperature has been observed since the 1980s, with a corresponding change in water temperature which may benefit Eurasian minnow. In warm summers, water temperature approaches 14°C which has proved to be near to the upper thermal threshold for Lepidurus arcticus.

Female proportion has a stronger influence on dispersal than body size in nematodes of mountain lakes.

Nematodes disperse passively and are amongst the smallest invertebrates on Earth. Free-living nematodes in mountain lakes are highly tolerant of environmental variations and are thus excellent model organisms in dispersal studies, since species-environment relationships are unlikely to interfere. In this study, we investigated how population or organism traits influence the stochastic physical nature of passive dispersal in a topologically complex environment. Specifically, we analyzed the influence of female proportion and body size on the geographical distribution of nematode species in the mountain lakes of the Pyrenees. We hypothesized that dispersal is facilitated by (i) a smaller body size, which would increase the rate of wind transport, and (ii) a higher female proportion within a population, which could increase colonization success because many nematode species are capable of parthenogenetic reproduction. The results showed that nematode species with a low proportion of females tend to have clustered spatial distributions that are not associated with patchy environmental conditions, suggesting greater barriers to dispersal. When all species were pooled, the overall proportion of females tended to increase at the highest elevations, where dispersal between lakes is arguably more difficult. The influence of body size was barely relevant for nematode distributions. Our study highlights the relevance of female proportion as a mechanism that enhances the dispersal success of parthenogenetic species, and that female sex is a determining factor in metacommunity connectivity.

Estimation of Phytoplankton Primary Productivity in Qinghai Lake Using Ocean Color Satellite Data: Seasonal and Interannual Variations

Estimation of primary production in Qinghai Lake is crucial for the aquatic ecosystem management in the northeastern Qinghai–Tibet Plateau. This study used the Vertically Generalized Production Model (VGPM) with ocean color satellite data to estimate phytoplankton primary productivity (PP) in Qinghai Lake during the non-freezing period from 2002 to 2023. Field data from 2018 and 2023 were used to calibrate and verify the model. The results showed a seasonal trend in chlorophyll-a and PP, with the lowest values in May and peaks from June to September. Qinghai Lake was identified as oligotrophic, with annual mean chlorophyl-a of 0.24–0.40 µg/L and PP of 40–369 mg C/m2/day. The spatial distribution of PP was low in the center of the lake and high near the shores and estuaries. An interesting periodic increasing trend in PP every 2 to 4 years was observed from 2002 to 2023. This study established a remote sensing method for PP assessment in Qinghai Lake, revealing seasonal and interannual variations and providing a useful example for monitoring large saline mountain lakes.

Tourism Through Local Eyes: A Potential Assessment of Danawan Lake

Tourism bridges different aspects together. It depends most of its assets on the abundance of nature. This study was conducted in Danawan Lake, located at Sitio Darayaw, Panaytayan, Mansalay, Oriental Mindoro. This study, in partnership with the local government unit, is focused on the potential assessment of Danawan, a mountain lake, with a specific lens on gauging community perception when it comes to tourism development. Aside from the physical attributes of a destination, community participation in tourism development is very important as it will dictate its sustainability. This ethnographic study employed a qualitative approach from SWOT analysis through observation, mapping, and personal interviews. The results showed that Danawan Lake has potential for adventure and ecotourism, but its sustainable development requires careful consideration of both strengths and weaknesses, opportunities, and threats. The indigenous community living near the lake has signified their acceptance of tourism activities and development in the area if advanced communication is considered. Collaboration and inclusivity should be at hand to attain the desired goals reflecting that the community considers the lake sacred. Future researchers may use other alternative potential assessment tools to gain more in-depth findings.

Lake Surface Water Temperature in high altitude lakes in the Pyrenees: Combining satellite with monitoring data to assess recent trends

Lake Surface Water Temperature (LSWT) influences critical bio-geological processes in lake ecosystems, and there is growing evidence of rising LSWT over recent decades worldwide and future shifts in thermal patterns are expected to be a major consequence of global warming.At a regional scale, assessing recent trends and anticipating impacts requires data from a number of lakes, but long term in situ monitoring programs are scarce, particularly in mountain areas. In this work, we propose the combined use of satellite-derived temperature with in situ data for a five-year period (2017–2022) from 5 small (<0.5km2) high altitude (1880–2680 masl) Pyrenean lakes. The comparison of in situ and satellite-derived data in a common period (2017–2022) during the summer season showed a notably high (r = 0.94, p < 0.01) correlation coefficient, indicative of a robust relationship between the two data sources. The root mean square errors ranged from 1.8 °C to 3.9 °C, while the mean absolute errors ranged from 1.6 °C to 3.6 °C.We applied the obtained in situ-satellite eq. (2017–2022) to Landsat 5, 7 and 8/9 data since 1985 to reconstruct the summer surface temperature of the five studied lakes with in situ data and to four additional lakes with no in situ monitoring data. Reconstructed LSWT for the 1985–2022 showed an upward trend in all lakes. Moreover, paleolimnological reconstructions based on sediment cores studies demonstrate large changes in the last decades in organic carbon accumulation, sediment fluxes and bioproductivity in the Pyrenean lakes.Our research represents the first comprehensive investigation conducted on high mountain lakes in the Pyrenees that compares field monitoring data with satellite-derived temperature records. The results demonstrate the reliability of satellite-derived LSWT for surface temperatures in small lakes, and provide a tool to improve the LSWT in lakes with no monitoring surveys.

EFFECT OF TOURIST TRAFFIC ON THE ECOSYSTEM OF LAKE MORSKIE OKO

Abstract. The Tatra National Park is the most frequently visited national park in Poland. Its most popular tourist trail is the route to Lake Morskie Oko, the second largest lake in the Tatra Mountains, and the best known mountain lake in Poland. The paper is based on results of field observations, and the analysis of literature and statistical data. The ecosystem of Morskie Oko in this paper is defined as the area of the lake’s catchment. The unique character of Morskie Oko is reflected by its recognition by “The Wall Street Journal” as one of five most beautiful lakes in the world. This results in exceptionally high interest of tourists in the lake despite the difficulties reaching the place. It takes walking a nine-kilometre route with a height difference of 420 m. Study results show the annual attendance of the place by more than a million people, whereas the number of tourists per day can exceed 10,000. The tourist traffic evidently intensifies between June and September. It results in high human pressure on the lake’s waters and surroundings, leading to the degradation of most components of the natural environment. Such high traffic intensity is frequently a nuisance for tourists using the trails themselves. Moreover, high tourist traffic contributes to the intensification of slope processes, resulting in mass movements in the form of debris and snow avalanches, potentially changing the course of the trails.

Assessing ecosystem services of mountain lakes

From global to local scales, human-induced environmental changes can impact mountain lakes by, for example, altering species composition, trophic state, and thermal dynamics, thereby affecting ecosystem functions and processes. However, the consequences of these changes on ecosystem services (ES) of mountain lakes are unclear due to a lack of integrative assessments. Therefore, this dissertation adopts an interdisciplinary ES perspective to improve insight into human interactions with mountain lakes and the potential social and ecological impacts of anthropogenic pressures on them. Stakeholder consultations highlighted the importance of regulating, cultural, and provisioning ES of natural mountain lakes, emphasizing habitat, aesthetics, recreation, education and research, and surface water, with nature-based experiences as being a key aspect of human interaction with mountain lakes. Multiple indicators were proposed to quantify potential supply of these ES, revealing variations among case study lakes in the European Alps. These results informed an integrative valuation approach and exposure assessment to anthropogenic pressures, suggesting that ES by mountain lakes are sensitive to climate change-related and human use pressures. Overall, the findings advance a social-ecological understanding of mountain lakes and indicate towards the need for adaptive lake management to maintain ES under potential anthropogenic pressure.

Altitudinal variation of microplastic abundance in lakeshore sediments from Italian lakes

Microplastic (MP) contamination represents an issue of global concern for both aquatic and terrestrial ecosystems, but only in recent years, the study of MPs has been focused on freshwaters. Several monitoring surveys have detected the presence of a wide array of MPs differing in size, shape, and polymer composition in rivers and lakes worldwide. Because of their role of sink for plastic particles, the abundance of MPs was investigated in waters, and deep and shoreline sediments from diverse lakes, confirming the ubiquity of this contamination. Although diverse factors, including those concerning anthropogenic activities and physical characteristics of lakes, have been supposed to affect MP abundances, very few studies have directly addressed these links. Thus, the aim of the present study was to explore the levels of MP contamination in mountain and subalpine lakes from Northern Italy. Fourteen lakes dislocated at different altitudes and characterized by dissimilar anthropic pressures were visited. Lakeshore sediments were collected close to the drift line to assess MPs contamination. Our results showed the presence of MPs in lakeshore sediments from all the lakes, with a mean (± standard deviation) expressed as MPs/Kg dry sediment accounting to 14.42 ± 13.31 (range 1.57–61.53), while expressed as MPs/m2, it was 176.07 ± 172.83 (range 25.00–666.67). The MP abundance measured for Garda Lake was significantly higher compared to all the other ones (F1,13 = 7.344; P < 0.001). The pattern of contamination was dominated by fibers in all the lakes, but they were the main contributors in mountain lakes. These findings showed that the MP abundance varied according to the altitude of the lakes, with higher levels measured in subalpine lakes located at low altitudes and surrounded by populated areas.

Diversity and Population Sizes of Wintering Waterbirds in the Wetlands of the Saïss-Middle Atlas Region (North-Central Morocco): Main Survival Factors and Evaluation of Habitat Loss.

Moroccan wetlands host up to half a million wintering birds and provide a stopover for tens of thousands of migrants, while they are inhabited by few nesting species. Most of this avifauna prefers to use the large coastal wetlands or reservoirs, while many species are dispersed across hundreds of small inland wetlands of various types. In this study, we monitored the wintering avifauna of 11 wetlands of the Saïss plain and its adjacent Atlas Mountains (north-center of Morocco), during six wintering seasons (2017-2018 to 2022-2023), with the objective of assessing the importance of this region as a waterbird wintering area. Using the richness of the species, we determine the bird population changes during this pentad and between the different types of wetlands (natural, human-made, and natural wetlands). During this study, we recorded 51 species, belonging to 17 families, among which exist four remarkable birds: the endangered Oxyura leucocephala, the vulnerable Aythya ferina and the near-threatened Aythya nyroca and Limosa limosa. Bird diversity is higher in human-made ecosystems than in peri-urban and natural ecosystems, while the populations' size is similar in urban and non-urban wetlands. With regard to bird conservation, these inland wetlands, mainly the small ones, are threatened by recurrent droughts and various anthropic stressors, which we describe using our observations of the two last decades (2003-2023). The loss of habitat is significant, reaching 348.5 hectares, while the impacts of reduced precipitation and temperature increase are particularly evident in the mountainous natural lakes.

Application of Biolog Ecoplate™ Technique for Assessing the Effects of Macrophyte Harvesting on Aquatic Bacterial Communities

Macrophyte overgrowth in freshwater ecosystems is a worldwide problem, and a common management practice for these ecosystems is to remove the aquatic vegetation. In the study, the short-term effects of macrophyte harvesting in a mountain lake (Trevnoto Lake, Bulgaria) on both bacterial metabolic activity and fingerprints were assessed using Biolog Ecoplate™ assay. Bacterial responses to human activity were manifested by: 1) increased bacterial metabolic activity by 15%, and 2) shifts in bacterial metabolic fingerprints. The most affected carbon sources were those with low availability for aquatic bacteria – 85% of them were influenced and the rates of their utilizations changed from a decrease of 96% to an increase of 681%. In general, a clear trend was formed that the greater the bioavailability of the carbon sources, the less susceptible is their utilization to the environmental change. This preliminary study indicates an immediate impact of macrophyte harvesting on lake bacteria. In this aspect, Biolog Ecoplate™ assay could be useful in lake monitoring programmes in order to develop better sustainable management practices for restoration.