Search

The zooplankton of the lakes Borodaevskoe and Ferapontovskoe (Russky Sever (Russian North) National Park) has been studied in 1975, 2008, and 2021. The zooplankton composition is similar in the lakes. In total, 70 zooplankton species are registered (21 species of Rotifera, Cladocera, 32, Copepoda, 17). The relict species Limnocalanus macrurus has been found earlier in the lakes. The zooplankton abundance is higher in the shallower Lake Borodaevskoye. The ratio of zooplankton groups in the water bodies was similar throughout the study period, with crustaceans as dominating group. The core of dominants includes 5 to 7 species (Kellicottia longispina, Diaphanosoma brachyurum, Daphnia сucullata, D. сristata, Bosmina coregoni, Mesocyclops leuckarti, and Thermocyclops oithonoides). The zooplankton abundance depends on the water temperature. As the latter has increased by 5 °С in summer 2021, there was an increase in the abundance and biomass of zooplankton in deep water areas of the studied lakes.

Small lakes are important elements of the ecosystem, especially under conditions of climate change and active water use. Studying their condition is of key importance for understanding the water balance and biodiversity of the region. This study compares remote sensing techniques for small lakes using Landsat-8, Sentinel-2, Planet and unmanned aerial vehicle (UAV) data. The aim of the work is to determine the most effective approach for monitoring lake conditions by analyzing the accuracy of different methods and indices. The methods used include the analysis of multispectral data such as NDWI, MNDWI and AWEI, which allow the distinction between aquatic and non-aquatic objects. The scientific significance of the study lies in assessing the potential of modern remote sensing technologies for detailed monitoring of ecosystem changes. Practical significance of the work consists in providing recommendations for sustainable water resources management and development of adaptation strategies. The research methodology included processing satellite data of different resolutions, accuracy verification using UAV reference data, and application of spectral indices for water surface mapping. Results showed that high-resolution imagery (PlanetLab data) most closely matched field observations. The spectral indices NDWI, MNDWI and AWEI showed different accuracy depending on data characteristics and lake features. The analysis confirms the effectiveness of an integrated approach using high-resolution data and spectral indices for monitoring the condition of small lakes. The practical value of the study lies in optimizing the monitoring of water bodies and maintaining their ecological sustainability. [ABSTRACT FROM AUTHOR]

In the conditions of growing anthropogenic pressure, aquatic ecosystems all over the world are subject to transformation, expressed in the growth of eutrophication, increase in acidity, changes in water exchange, etc. In the region of Eastern Siberia we studied, located in Yakutia in the middle reaches of the Lena River basin, there is a significant population growth accompanied by advancements in agriculture and public utilities. The region is rich in small lakes, which have been under pressure from human activities for the past few decades. The studied region is located in the permafrost zone and is characterized by severe climatic conditions, cold long winters, short hot summers, and a short ice-free period on reservoirs. We studied 17 lakes of various genesis, with varying degrees of anthropogenic pressure, located in the largest city of the region, small villages, and at different distances from them. Previous studies have established that cyanobacteria constitute the phytoplankton main group in these lakes during the summer period. Therefore, we selected them as the focus for our bioindication analysis. An integrated assessment of the bioindication properties of cyanobacteria, along with chemical water parameters, was undertaken using statistical mapping methods, JASP, and Redundancy Analysis (RDA). This analysis revealed the impact of urbanized areas, characterized by a decrease in pH, runoff of nitrogen compounds, and an increase in organic matter. Despite the cryolithozone harsh conditions, in small lakes of urbanized areas, cyanobacteria exhibit their competitive advantages within the plankton community. The prospect of continuing our work is associated with the need to determine the risk of cyanoHAB development since potentially toxic cyanobacteria have a mass development in a number of lakes. [ABSTRACT FROM AUTHOR]

Numerous policies have been proposed by international and supranational institutions, such as the European Union, to surveil Earth from space and furnish indicators of environmental conditions across diverse scenarios. In tandem with these policies, different initiatives, particularly on both sides of the Atlantic, have emerged to provide valuable data for environmental management such as the concept of essential climate variables. However, a key question arises: do the available data align with the monitoring requirements outlined in these policies? In this paper, we concentrate on Earth Observation (EO) optical data applications for environmental monitoring, with a specific emphasis on ocean colour. In a rapidly changing climate, it becomes imperative to consider data requirements for upcoming space missions. We place particular significance on the application of these data when monitoring lakes and marine protected areas (MPAs). These two use cases, albeit very different in nature, underscore the necessity for higher-spatial-resolution imagery to effectively study these vital habitats. Limnological ecosystems, sensitive to ice melting and temperature fluctuations, serve as crucial indicators of a climate in change. Simultaneously, MPAs, although generally small in size, play a crucial role in safeguarding marine biodiversity and supporting sustainable marine resource management. They are increasingly acknowledged as a critical component of global efforts to conserve and manage marine ecosystems, as exemplified by Target 3 of the Kunming–Montreal Global Biodiversity Framework (GBF), which aims to effectively conserve 30% of terrestrial, inland water, coastal, and marine areas by 2030 through protected areas and other conservation measures. In this paper, we analysed different policies concerning EO data and their application to environmental-based monitoring. We also reviewed and analysed the existing relevant literature in order to find gaps that need to be bridged to effectively monitor these habitats in an ecosystem-based approach, making data more accessible, leading to the generation of water quality indicators derived from new high- and very high-resolution satellite monitoring focusing especially on Chlorophyll-a concentrations. Such data are pivotal for comprehending, at small and local scales, how these habitats are responding to climate change and various stressors. [ABSTRACT FROM AUTHOR]

Changes in the macrozoobenthos of two northern lakes differing in degree of humification of water over the 50-year period that have passed since the first studies were considered. In the lake with water uncolored by humus, the benthos biomass increased, and in the humified one, it decreased. The changes that have occurred are due to climate warming, especially pronounced in winter. It was concluded that even closely located bodies of water can respond differently to climate change. Depending on the nature of the catchment area and the morphology of the lakes, either an increase in their productivity due to the supply of nutrients or a decrease due to humification can be observed. [ABSTRACT FROM AUTHOR]

Primary studies of the concentrations of rare elements in the sediments of two lakes on King George Island (Kitezh and Glubokoe) showed that their geochemistry reflects the geological features of the area. Compared to the composition of the upper part of the Earth's crust, the studied sediments are enriched in Cu, Cd, V, Tl, Mn, Ti, and P. Similar patterns have been identified in the geochemistry of volcanic and sedimentary rocks of the Fildes Peninsula. Trends in REE changes generally follow their behavior in rocks, but the overall REE concentration in sediments of lakes is higher, which may be due to the presence of organic matter accumulating in sediments of water bodies. Unlike the aquatic environment, the chemical composition of sediments does not reflect the significant influence of the activities of polar stations. However, small increases in Pb and Sb concentrations in the upper sediments suggest the influence of long–range atmospheric transport of the contaminants. [ABSTRACT FROM AUTHOR]

Small floodplain lakes (SFLs), characterized by their diminutive size (

This study provides the first long-time series of spatial and temporal distributions for small lakes in the Larsemann Hills (69°23′S, 76°20′E) in the East Antarctic. In the Larsemann oasis, there is a significant number of over 150 small lakes, which can be observed with high spatial resolution in remote sensing imagery. However, accurately identifying and analyzing these small water bodies and elongated rivers has been challenging due to the mixed pixels effect and limitations in available middle spatial resolution imagery. In our study, we propose a data-driven approach within the conditional random fields framework, which considers three scales: superpixel, pixel, and subpixel, to refine the boundaries of small water bodies efficiently. The superpixel level quickly identifies the main water body and normalized difference water index provides a buffer region, while the pixel level employs support vector machine (SVM) to obtain a more precise boundary. Subpixel mapping technology within the pixel level further reduces mixed pixel effects for improved accuracy. The waterbodies were extracted from Sentinel-2 images with a spatial resolution of 10 m. The lake boundaries derived from the proposed algorithm in this study showed good agreement with in situ measurements of the lake shoreline delineated by aerial images from the 39th Chinese Antarctic Scientific Expedition. The analysis revealed distinct seasonal patterns across the Larsemann Hills, while the lake areas achieved their peak extents earlier, specifically in February before 2020 and in January after 2020. The water body mapping based on the proposed algorithm can contribute to Antarctic remote sensing hydrological observations, particularly in the monitoring of outburst events. These findings demonstrate the potential of extending this method to other Antarctic oases to enhance intra-annual lake observations. Moreover, Sentinel-2 images provide valuable remote sensing data for studying the seasonal cycles of water bodies, including those of varying sizes in the Larsemann Hills, based on long-term time series imagery.

Small lakes play an essential role in maintaining regional ecosystem stability and water quality. However, turbidity in these lakes is increasingly influenced by anthropogenic activities, which presents a challenge for traditional monitoring methods. This study explores the feasibility of using consumer-grade UAVs equipped with RGB cameras to monitor water turbidity in small lakes within the Taihu Lake Basin of eastern China. By collecting RGB imagery and in situ turbidity measurements, we developed and validated models for turbidity prediction. RGB band indices were used in combination with three machine learning models, namely Interpretable Feature Transformation Regression (IFTR), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). Results showed that models utilizing combinations of the R, G, B, and ln(R) bands achieved the highest accuracy, with the IFTR model demonstrating the best performance (R² = 0.816, RMSE = 3.617, MAE = 2.997). The study confirms that consumer-grade UAVs can be an effective, low-cost tool for high-resolution turbidity monitoring in small lakes, providing valuable insights for sustainable water quality management. Future research should investigate advanced algorithms and additional spectral features to further enhance prediction accuracy and adaptability.

The phytoplankton composition, TN:TP ratios as the limiting factor on phytoplankton and the trophic Status of Lake Karagöl, a small volcanicoriginated lake, were first investigated in this study. Additionally, the physicochemical parameters of the lake were measured. As a result of the investigations, 21 dominant taxa from four divisions among phytoplanktonic organisms were identified in Karagöl. Three taxa belonged to Cyanobacteria, eleven to Chlorophyta, six to Ochrophyta (only Bacillariophycea), and to one to Myzozoa. The average depth of the lake was calculated as 8.7 m. In line with the atmospheric temperatures brought by the Mediterranean climate prevailing in the region, surface water temperatures of the lake fluctuated between 23.0 °C (summer) and 6.5 °C (winter). Conductivity ranged from 780 to 423 µS and dissolved oxygen ranged from 15.3 to 7.3 mg l-1. The average scores of TSI (SD), TSI (Chl-a), TSI (TN) and TSI (TP) were calculated as 68.0, 55.1, 62.1 and 86.4 respectively. These TSI scores indicated that Lake Karagöl was at eutrophic or hypereutrophic levels. TN:TP ratio of the lake ranged from 9.8 to 7.2 and in this case, the Lake Karagöl food chain is nitrogen-limited because of the low TN:TP ratios. Dolichospermum flosaquae (N2-fixing heterocystous Cyanobacteria) was the dominant species in Lake Karagöl phytoplankton during the summer months when the high-water temperature. As a result of this study, based on phytoplankton composition, dominant algae groups (especially Cyanobacteria) and TSI scores, it was evaluated that Lake Karagöl (Dikili) has suitable environmental conditions for many algae species found in mesotrophic and eutrophic lakes and is in a very rapidly progressing hypertrophication process. [ABSTRACT FROM AUTHOR]

Small lakes (areas ranging from 0.01 km2 to 1 km2) are highly sensitive to climate change and human activities. However, few studies have investigated the long-term intra-annual trends in the number and area of small lakes and their driving mechanisms in the Qinghai–Tibet Plateau (QTP). As a significant water tower in northwest China, the Qilian Mountains region (QMR) in the QTP is essential for sustaining regional industrial and agricultural production, biodiversity, and human well-being. We conducted an analysis of the dynamics of small lakes in the QMR region. In this study, we employed Geodetector and examined nine factors to investigate the driving mechanisms behind the long-term variations in the small lake water bodies (SLWBs). We specifically focused on understanding the effects of single-factor and two-factor interactions. The results indicate that the number and area of small lakes had a fluctuating trend from 1987 to 2020. Initially, there was a decrease followed by an increase, which was generally consistent with trends in the large lakes on the QTP. All basins had far more expanding than shrinking lakes. The area of seasonal SLWBs in each basin was increasing more rapidly than permanent SLWBs. The distribution and trends in the area and number of small lakes varied widely across elevation zones. Runoff, snow depth, and temperature contributed the most to SLWB changes. Human activities and wind speed contributed the least. However, the main drivers varied across basins. The impact of two-factor interactions on SLWB changes in basins was greater than that of single factors. Our results provide useful information for planning and managing water resources and studies of small lakes. [ABSTRACT FROM AUTHOR]

The problem of eutrophication of the waters in remote Arctic regions is discussed as a consequence of climate warming and global dispersion of phosphorus. The analysis of long-term monitoring results of water quality from 1990 through 2018 (once every four to five years) provides evidence that the total concentrations of phosphorus and nitrogen, as well as organic matter, had increased by the last decade, which is confirmed by reliable relationships with temperature conditions. The fluxes of phosphorus into lakes from drainage areas were calculated using V.V. Bouillon's model and turned out to grow during the last decade. The trophic status indicator (TSI) of the lakes shows that the number of oligotrophic lakes has decreased and the number of meso- and eutrophic ones has increased even where no influence of any anthropogenic factors was identified. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The chemical composition and seasonal dynamics of the water in Murmansk urban lakes (Murmansk region, Russia) under the anthropogenic load of varying intensity was analysed. The studies were conducted in the period from 2018 to 2020. The chemical composition of the water in the studied lakes differed significantly from that of the lakes located in the background territories of the region. High values of pH and mineralization, increased concentrations of major ions and elevated content of nitrogen and phosphorus compounds were recorded in the surface waters. The nutrient concentrations were subject to noticeable seasonal fluctuations, mainly due to their consumption by phytoplankton, as well as to the changes in the ratios of surface and underground runoff. Lake Ledovoe (the central part of Murmansk) was the most polluted among the studied lakes, and Lake Bolshoe (used for drinking supply of the city) was the least polluted. Assessing the trophic status of the Murmansk lakes showed that the studied lakes are mostly mesotrophic, except for Lake Bolshoe (oligotrophic) and Lake Ledovoe (hypertrophic). In most of the lakes, phosphorus was the limiting factor for the growth and development of phytoplankton. The data obtained can be useful for understanding the fundamental processes of water composition transformation in the urbanized territories of the Arctic regions of the world and for making managerial (practical) decisions to create a comfortable urban environment in the North of Russia. [ABSTRACT FROM AUTHOR]

Species distribution and assemblage structuring are influenced by a combination of species dispersal mode and the dispersal routes used. Habitat connectivity is particularly important for passively dispersing taxa such as freshwater molluscs. In addition, current anthropogenic eutrophication affects the structure of assemblages by reducing native fauna and promoting the spread of generalist species. Here, we examined mollusc assemblages in two systems of small lakes differing in hydrological connectivity. The assemblages of 22 isolated lakes in Albania were mainly controlled by the distance between the lakes with a lower contribution of environmental conditions and lake area. In contrast, assemblages of 52 interconnected lakes in Czechia were driven primarily by environmental conditions. However, as lake trophic status increased, the assemblages in Czechia became more homogeneous in species composition as high trophic status filtered out all species except generalists. These assemblages from 33 eutrophic lakes were strongly determined by environmental variables, whereas the remaining assemblages from 19 low trophic lakes were structured by a combination of spatial and environmental variables. We conclude that hydrological connectivity between lakes is crucial for the distribution of molluscs, but eutrophication may influence the importance of individual mechanisms structuring mollusc assemblages. [ABSTRACT FROM AUTHOR]

The Local Government and the Government Agency shape the Seven Crater Lakes. The present study focused on understanding the predominant Governments and Lake Governance's concept vis‐a‐vis the small lakes and their basin communities. These foremost authorities are intertwined, and Lake Governance's essential criteria interplayed and continuous to the responsibility. Although the City Government of San Pablo City and the Laguna Lake Development Authority (LLDA) have improved the small lake's situations and they are satisfactorily functioning, serious issues still remain at present and into the future. Focusing on the criteria's lessons, Pandin Lake, Yambo Lake, Mohicap Lake and Sampaloc Lake have been ameliorated to varying degrees. In contrast, Bunot Lake, Palakpakin Lake and Calibato Lake continue to struggle with deficiencies. Thus, over the dual governments need to exhibit greater commitment, decisiveness and effectiveness if the Seven Crater Lakes are to flourish in development and conservation. Furthermore, while the Structuring Government and Administering Water criteria are adequate, completing the Developing Tourism, accomplishing the Regulating Fishery and substantially subsidizing the Supporting Finance in the City Government and the LLDA remain deficient. Accordingly, the main target of the paired Governments' over time is to address the remaining challenges facing the Seven Crater Lakes. [ABSTRACT FROM AUTHOR]

Dense submerged macrophyte stands in lakes may promote alternating daytime stratification and nighttime convective mixing, driving extensive spatiotemporal variations in water temperature, oxygen, pH, and inorganic carbon (DIC). We set out to investigate environmental conditions and ecosystem metabolism in the macrophyte‐dominated littoral zone (0.6 m depth) of a shallow, mesotrophic lake and compared this with the pelagic zone (3.0 m deep). We found that, during summer, vertical water column gradients only occasionally occurred and were weak in the pelagic zone, while dense littoral macrophyte stands of charophytes exhibited strong diel changes and steep daytime temperature and oxygen depth gradients. Oxygen showed daytime surface supersaturation and bottom anoxia, alternating with nighttime mixing. In spring, before charophytes appeared, the vertical gradients were largely absent. Ecosystem metabolism was primarily positive in spring, but areal rates of daily gross primary production (GPP) and closely related respiration increased 6‐fold in summer. Ecosystem metabolism calculated based on oxygen or DIC was very similar, with a 1:1 M basis. Daytime DIC loss by CaCO3 precipitation on charophyte surfaces averaged 6.3% of total DIC loss, and this loss was restored during nighttime. The contribution of shallow littoral macrophyte communities to whole‐lake summer GPP exceeded that estimated for phytoplankton. Environmental conditions in the macrophyte‐covered littoral zone differed markedly from pelagic waters with steep vertical gradients in temperature and chemistry during daytime including anoxic micro‐habitats in stark contrast to deep pelagic waters. The study highlights the significant influence of the littoral zone and macrophytes on whole‐lake ecosystem processes. Plain Language Summary: In shallow water in clear‐water lakes where light reaches the bottom, dense stands of submerged plants may develop. Dense plant stands promote stratification of the water column resulting in large differences in water temperature, oxygen, pH, and dissolved inorganic carbon between surface and bottom waters. We set out to investigate how dense plant stands in the shallow water of a nutrient‐poor lake influence environmental conditions and compare this to open waters. During summer, we found small differences between the surface and bottom water at the open water site, while pronounced differences developed in dense plant stands in the shallow water site. During daytime, oxygen was high in surface water with high photosynthesis, while respiration consumed virtually all oxygen in dim light below the plant canopy close to the bottom. During nighttime, differences vanished due to surface cooling, which promotes mixing of the entire water column. Two independent methods showed a close 1:1 balance between oxygen production and consumption and complementary carbon consumption and production in photosynthesis and respiration, respectively. Our study highlights the differences between shallow and open waters and the prominent role that plants may play in productivity and environmental conditions in the whole lake. Key Points: Extensive diel and depth variation in temperature, oxygen and pH occurred in dense littoral macrophyte stands in a small mesotrophic lakeMetabolism of oxygen and dissolved inorganic carbon were closely coupled and photosynthesis and calcification peaked before noonSensor measurements reveal the extensive variability of physical mixing, chemical gradients, and metabolism in dense macrophyte stands [ABSTRACT FROM AUTHOR]

The relict northern European arctic-boreal species Mysis relicta Lovén, 1862 has been recorded in the Volga River basin after 90 years; it had previously been found once in the gut of a European perch. Ten specimens were registered at depths of 26.5 and 32.9 m in July 2021 in the small Lake Svyatozero, located in Vashkinsky District, Vologda oblast (60°26′ N, 37°49′ E). The data on the species habitat in Lake Svyatozero and the possibility of finding this species in other small lakes in the southeastern part of the range have been analyzed. It is recommended to include M. relicta in the new edition of the Red Data Book of Vologda Oblast with 1/CR/I protection status. [ABSTRACT FROM AUTHOR]

Various components of lake systems located in different landscape zones in southern West Siberia were studied for contents of natural and artificial radionuclides, following the requirements of the state standards (GOST). This work aims at assessing the radiation state of lacustrine sapropel sediments in the Baraba lowland and Kulunda plain, taking into account their natural features and the degree of contamination during nuclear tests. It was found out that the values of the total effective specific activity (As) of natural radionuclides in all of the sapropel lacustrine sediments are significantly lower than the standard value (according to the requirements of the GOST). Some sapropel horizons in the lakes contain excess 137Cs reserves that are twice as high as the global background. Such lakes tend to be spatially constrained to areal traces of radioactive fallouts after nuclear tests at the Semipalatinsk test site and undoubtedly belong to lake systems whose waters and soils on catchments were primarily contaminated with radiocesium. [ABSTRACT FROM AUTHOR]

Mountain lakes are unique and often isolated freshwater habitats that harbour a rich biotic diversity. This high conservation value may be reflected by diatoms, a group of algae that is known for its reliability as a bioindicator, but which has not been studied extensively in mountain lakes of the northern European Alps. In this study, the conservation value of these lakes was assessed by characterizing the number, share, and abundance of diatom Red List (RL) taxa and their relationship with environmental variables, diatom α and β diversity (assemblage uniqueness). For this purpose, linear regression models, generalized linear models, and generalized additive models were fitted and spatial descriptors were included when relevant. Of the 560 diatom taxa identified, 64% were on the RL and half of these were assigned a threat status. As hypothesized, a decreasing share of RL species in sediment and littoral samples at higher trophic levels was reflected by higher total phosphorous content and lower Secchi depth, respectively. Species-rich lakes contained a high number of RL taxa, contrasting our hypothesis of a logarithmic relationship. In turn, RL abundance increased with uniqueness, confirming our initial hypothesis. However, some of the most unique sites were degraded by fish stocking and contained low abundances of RL species. The results demonstrate the importance of oligotrophic mountain lakes as habitats for rare freshwater biota and their vulnerability in light of human impact through cattle herding, tourism, damming, and fish stocking. Additional conservation efforts are urgently needed for mountain lakes that are still underrepresented within legal conservation frameworks. Species richness and uniqueness reflect complementary aspects of RL status and thus should be applied jointly. Uniqueness can indicate both pristine and degraded habitats, so that including information on human impacts facilitates its interpretation. [ABSTRACT FROM AUTHOR]

Factors of formation of phosphorus load on lakes of various landscapes (from tundra to steppe zone) are considered. The calculations of the balance model showed that the phosphorus load is predominantly determined by the conditional water exchange, specific catchment area, and runoff module. Statistical analysis demonstrated that phosphorus fluxes in lakes are determined by the cumulative impact of landscape (swamp and forest areas), climatic (annual precipitation, sum of active temperatures, duration of the vegetation period). Lakes from the tundra to forest-steppe zones are characterized by the low (mesotrophic) trophicity, while lake from the steppe zone reveals the high (eutrophic) trophicity. The factual phosphorus loads in lakes during the autumn homothermy were calculated and analyzed compared to the critical loads during the period of spring mixing. [ABSTRACT FROM AUTHOR]

The paper reports the results of the analysis of Pb, Sb, Cd accumulation in top core sediments from small lakes of southern Republic of Karelia. Both lakes in urban areas (Petrozavodsk, Medvezhyegorsk, Suojarvi, and Sortavala) and lakes in areas regarded as reference for southern Karelia were included in the study. Fieldwork and analytical investigations employed a common methodology in line with globally-accepted limnological practices. The concentrations of chemical elements in the lake sediments were determined by inductively coupled plasma mass spectrometry (ICP-MS). The median background concentrations of Pb, Sb, Cd in the studied sediments deposited in the preindustrial period were calculated, and the recent levels of accumulation of these metals in the industrial period were determined for the same lakes. The main factors for the formation of technogenic Pb, Sb, Cd anomalies in the top core sediments are described, and the levels of the heavy metals are compared against those in lake sediments in other parts of the world. The levels of contamination of the Karelian lakes with these metals were calculated based on the geoaccumulation index Igeo. The Tessier sequential extraction procedure was employed to detect the main forms of the heavy metals in the top core sediments. Especially, the role of organic matter, which constitutes the bulk of the sediments, in binding the pollutants was assessed. Considering that Karelian lake sediments are potential sources of useful organic raw material, i.e. sapropel, some recommendations are given on the possible applications of these sediments in human activities.

The average background concentrations of 42 elements, including heavy metals which are the most dangerous pollutants of the environment, were calculated based on detailed research of sediments of 15 small lakes in the south of the Republic of Karelia. The sediment samples from the lakes were collected from 2016 to 2018. The main items of equipment were a gravity sampler Limnos and hand sampler. The former is capable of producing a 60 cm core and dividing it into 1 cm layers, the latter can enter sediment to a depth of 15 m. All samples were prepared by chemical analysis and measured using uniform methods. The concentrations of chemical elements were taken by the mass-spectral method on a ХSeries-2 ICP-MS. To reveal the layers accumulated in the pre-industrial period, similar research of the area of the Murmansk region and countries of the Scandinavian Peninsula were used. Besides this, the geochemistry and geochronology of lake studies of the author were also used. Eventually, from 73 to 76 samples were taken for an assessment of background concentrations of heavy metals and other elements in the sediments of the lakes from Karelia's south. Given that the data obtained do not obey the normal distribution law, which is often found in geochemistry, the median sample was taken as the averaged background concentration of chemical elements. The results were similar to analog data for neighboring regions, including the Murmansk region and Scandinavian countries. Moreover, the levels of accumulation of chemical elements in lake sediments of Karelia's south are similar to some of the data for stream sediments of the studied region. The exceptions were elements controlled by terrigenous fractions of the stream sediments. This fraction is more rapidly accumulated in the stream and river sediments than in lake sediments. New data can be used for future environmental and geochemistry studies of the sediments of small lakes subject to anthropogenic impact.

Background This paper provides current data on the biodiversity of boreal lakes of the Vologda Region (north-western Russia), including macrophytes (vascular plants and macroscopic algae) and macrophyte inhabitants (invertebrates and microalgae). The raw data, given in two datasets (Sampling event dataset and an Occurrence dataset) and presented in the form of GBIF-mediated data, were collected from 139 lakes (macrophytes between 2005 and 2021, macrophyte inhabitants between 2014 and 2020). The dataset contains materials on the diversity of vascular plants (Tracheophyta, 3225 occurrences; Bryophyta, 155; Marchantiophyta, 16), macro- and microalgae (Ochrophyta, 546 occurrences; Chlorophyta, 193; Charophyta, 153; Cyanobacteria, 139; Cryptophyta, 86; Myzozoa, 33; Euglenozoa, 27; Rhodophyta, 8; Bigyra, 1) and aquatic invertebrates (Arthropoda, 1408 occurrences; Annelida, 487; Mollusca, 263; Platyhelminthes, 36; Cnidaria, 11). This paper summarises previously unpublished materials in a standardised form. New information The paper summarises the data collected during the long-term phytodiversity studies in a series of lakes of different types (Vologda Region, north-western Russia). Data on algae and invertebrates diversity were obtained in 60 different plant communities of aquatic, semi-aquatic and coastal plants or their combinations. A total of 6787 occurrences were included in the dataset, published in the global biodiversity database (GBIF) for the first time. According to the GBIF taxonomic backbone, the dataset comprised 837 taxa, including 711 lower-rank taxa (species, subspecies, varieties, forms). New records of 47 species rare and protected in the Vologda Region are given: 43 species of plants, three species of animals and one species of Cyanobacteria. [ABSTRACT FROM AUTHOR]

The taxonomic structure, typology, species richness, and total abundance of bentic and littoral macroinvertebrate communities from small lakes of the Arctic and Subarctic zones are considered on the basis of original data from three northern Palearctic regions (the foot of the Putorana Plateau, Kolguev Island, and Western Svalbard Island). A comparative analysis of the communities of these regions has been carried out. The features of High Arctic insular, Low Arctic, subarctic, and boreal lake communities are discussed using a large volume of literature data. The complex pattern of changes in the total benthos biomass of small lakes has been revealed: it decreases in the subarctic taiga, increases in the hypoarctic tundra, and decreases again in the High Arctic. [ABSTRACT FROM AUTHOR]

The article presents the first data on the study of a wide range of chemical elements in the water and sediments of small lakes located in the Arctic Zone of Russia. Among the selected objects are two lakes located in the urbanized areas. As a result, the sediments of all lakes were classified by the ratio of the main elements and the total content of organic matter. The concentration coefficients of all elements were calculated taking into average concentrations of different elements in the continental crust and the potentially toxic elements in the sediments of the background area. Analyzing sediment cores made it possible to evaluate the historical dynamics of the behavior of some metals and metalloids (Pb, Cd, Sb, Sn, Bi, Ni, Cu) in the aquatic environment during the industrial era, both in urbanized territories and in the background regions of the Arctic. The main natural and anthropogenic factors of the formation of geochemical anomalies in the concentrations of different elements, including potentially toxic ones, in the sediments studied, were identified. In urban areas, the main sources of metals entering the lake environment are emissions of the copper–nickel, thermal power plants, coal port, and an incineration plant. For all lakes, the pollution level of objects was estimated by calculating the geo-accumulation index and pollution load index. The most polluted lakes are the lakes of urban areas of the Arctic, the lakes of the background territories are characterized by a moderate level of pollution or no pollution. [ABSTRACT FROM AUTHOR]

Extremely high uranium concentrations (>100 times average crustal content) are established in the recent sediments of small lakes of the northern Murmansk region. It is substantiated that the high uranium concentrations in the sediments of the lakes of the northern Murmansk region were mainly controlled by natural uranium migration from magmatic and metamorphic rocks bearing uranium mineralization (Litsa geological district). The sediments of the studied lakes display a tight correlation of uranium with Mo and rare earth elements usually accompanying uranium in parental rocks. The main chemical fractions of uranium in the lake sediments are revealed. It is shown that organic matter significantly affects the accumulation of this element in the lake sediments. [ABSTRACT FROM AUTHOR]

The management of French freshwater bodies (lakes, reservoirs, ponds, etc.) needs to face the challenges imposed by the effects of climate change and by legal requirements to develop standards for water temperature and other physicochemical indicators. While 1D hydrodynamical models could be helpful in improving the knowledge of the thermal and hydrodynamic behaviour of French water bodies, the scarcity of data for calibration and validation, in addition to the unavailability of some forcing data, makes their application difficult for most French water bodies. In this article we explore an alternative statistical approach that takes advantage of the available data in order to inform future modelling applications. We used official monitoring data and satellite measurements to study the thermal characteristics of more than 400 French water bodies (depth: 1–310 m, surface area: 0.1–577 km2, volume: 0.1–89,000 hm3). The objective was to identify the importance of size on their thermal behaviour. For this we analysed the annual temperature cycle, the summer temperature profiles and within-lake spatial variability. Together with size, geography and transparency determine the thermal behaviour of water bodies through complex interactions. As a result of the analysis we propose a classification of French water bodies as a function of depth and surface area that reflects the summer vertical temperature gradient and the processes influencing the deepening of the thermocline. [ABSTRACT FROM AUTHOR]

In this article, issues of environmental pollution due to long-range atmospheric transport of heavy metals are considered. Researches of recent sediment cores of Lakes Liunkunlampi and Raivattalanlampi from the Republic of Karelia were carried out. The purpose of the study was to give a detailed environmental and geochemical assessment of the recent sediments in these small lakes located in the southwestern part of Karelia. The scope of the study covers the area of the southwest of Karelia (Russia) and touches the environmental problems of northern Europe. The maximum of heavy metal accumulation appears in the upper sediment layers from 0 to approximately 15 cm. The main pollutants of the lakes are Pb, Cd, Zn, Cu, Sb, Sn, Bi, and Tl, which are geochemistry agents of long-range pollutant transport from anthropogenic sources of Russia, Finland and other countries of Northern and Eastern Europe. It was revealed that the type of sediments significantly influences the activity of heavy metal accumulation. The sediments of Lake Liunkunlampi contain more heavy metal concentrations than sediments of Lake Raivattalanlampi, because Liunkunlampi sediments consist of about 80% organic matter, whereas Raivattalanlampi sediments are made up of 26% organic matter. Analysis of fractions of heavy metals illustrated that pollutants basically are bound with mineral and organic phases of lake sediments in south-west Karelia. The high bioavailable of some metals (Cd, Pb, Zn) are noted. [ABSTRACT FROM AUTHOR]

Small lakes are numerous in the landscape and closely connected to the terrestrial environment, which strongly influences the system scale carbon cycling. However, despite their importance in large-scale carbon budgets, small lakes remain understudied compared to large lakes. We investigated oxygen and carbon dynamics in four small Danish forest lakes over a year. Continuous pH measurements were used to establish a high-frequency time series of CO2 partial pressure and 1169 direct measurements of air–water CO2 flux were performed using floating chambers. Net ecosystem oxygen production (NEP) was derived from free-water oxygen measurements in order to quantify the contribution of in-lake aerobic metabolism to the air–water CO2 flux. We found that the forest lakes, on average, were tenfold CO2 supersaturated. The two most intensively studied lakes had mean CO2 effluxes of 36.3 mol m−2 year−1. The CO2 effluxes exceeded NEP during all months implying that the CO2 generated by aerobic respiration alone could not account for the observed CO2 efflux. The observed discrepancy is likely promoted by a hydrologic CO2 input and/or anaerobic sediment processes generating CO2 without a concurrent consumption of O2. A broad-scale national analysis showed that the CO2 efflux increased as lake size decreased despite lower gas exchange velocity. Small lakes also showed higher excess CO2 efflux compared to O2 influx. Overall, small lakes and forest lakes in particular have high CO2 effluxes and high CO2 supersaturation. However, the contribution of hydrological inputs and anaerobic sediment processes to the net CO2 efflux remains elusive. [ABSTRACT FROM AUTHOR]

A quantitative assessment of the fractionation of elements during sedimentation is made based on long-term comprehensive studies with the participation of geochemists, hydrobiologists, soil scientists, and chemists. Analytical studies of the chemical composition of water, soil, bottom sediments, and biota were carried out at the Center for Collective Use of Scientific Equipment for Multielement and Isotope Studies and at the Institute of Catalysis, Novosibirsk. Based on a mineralogical and geochemical approach, we chose lakes with different types of biogenetic formation and different classes of organomineral sediments and performed detailed studies of the relationship between the organic and mineral parts of the sediments. It has been established that the organomineral sediments of different classes and biogenetic types of formation differ not only in the contents of major elements (Si, Ca, C, and O) but also in the group composition of organic matter. The direct effect of the transformation of organic matter on the mineral composition of bottom sediments has been revealed. The contents of other elements vary in a narrow range of values. At the same time, the difference in the contents of elements between organomineral sediments of different types and classes is comparable with their difference within a class. The leading role in the formation of the geochemical and mineral compositions of the organomineral sediments of small lakes belongs to intricate biological, biochemical, and physicochemical processes depending mainly on azonal factors and occurring under prolonged freezing-up (anaerobic conditions). [ABSTRACT FROM AUTHOR]

Theoretical pelagic primary production of phytoplankton and benthic primary production of periphyton were modelled for two small lakes in Estonia (Northeast Europe). Although located only 500 m apart, the water colour and light attenuation of these two lakes differed markedly. The Secchi depth (SD) in the clear‐water lake was 4.5 m and only 0.47 m in the dark‐water lake. The total phosphorus (TP) concentrations were, respectively, 15 μg/l and 28 μg/l. An empirical model whose inputs were morphometric, light conditions and dissolved organic carbon parameters obtained from in situ measurements was employed for the present study. The model calculated primary production with a time‐step of 10 min, and a spatial resolution of 10 cm, from sunrise to sunset and from lake surface to lake bottom. The primary production of periphyton and phytoplankton was almost equal in the clear lake, whereas only phytoplankton contributed to whole‐lake primary production in the dark lake because of the stronger light attenuation in the water column. The results of the present study indicated the depth‐distribution profiles differed dramatically between the two lakes. The clear lake had a deep, U‐shaped curve, with the productive layer reaching considerable depth soon after sunrise and maintaining a similar profile throughout the light hours. In contrast, the dark lake production declined rapidly with increasing depth, whereas the profile changed over the day reaching the greatest depth at noon. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the relationship between the development of rush zones in small lakes and the utilization and condition of surrounding lands. Generally, the width of the helophyte zone increased along shores with gentle slopes (>5˚) that were covered with vegetation. The most favourable conditions for rush development and spread were along sloped areas bordered by farmlands and rural developments. In addition, pasturelands that developed on top of peat accumulation adjacent to lakes were found to facilitate the development of rushes. We observed a positive effect of anthropogenic development, especially agriculture and infrastructure, on stem density and total biomass of Phragmites austalis populations in the lakes studied. However, individual stem biomass of plants was lower. In different parts of the studied lakes, macrophyte distribution patterns were influenced by environmental conditions including nutrient availability, wind exposure, and bottom slope. The poorest macrophyte communities were found in areas within the lakes that were shaded by trees growing on neighboring banks and where slopes were forested rush zones were absent altogether.

Complex ecological studies of five small lakes under direct impact of the Monchegorsk site of JSC «Kolskaya GMK» have been conducted. The lakes ecosystems develop under extreme pollution, and characterized by depleted species composition of hydrobionts and low values of their abundance and biomass. Lake Kumuzhye, with the least transformed watershed, is closest to natural environment. Lake Nyudyavr, affecting by cuprum-nikel production sewages is additionally susceptible to anthropogenic eutrophication, which obviously contributes in part to the resistance of hydrobionts to toxic load. It is established that the use of traditional hydrobiological criteria for assessment of water quality and trophic status for the studied water bodies is limited.

ABSTRAK Keberadaan logam berat di ekosistem akuatik telah sering dilaporkan menimbulkan masalah ke biota perairan. Salah satu biota perairan yang memiliki resiko untuk terpapar logam berat dari sedimen adalah organisme makrozoobentos. Penelitian ini bertujuan untuk mendeskripsikan pengaruh kontaminasi logam berat di sedimen pada struktur komunitas makrozoobentos yang berada di ekosistem lentik (situ dan waduk). Penelitian ini telah dilakukan pada bulan Juni 2009 - September 2011 di beberapa situ dan waduk yang berada di Provinsi Jawa Barat dan Jakarta. Sampel makrozoobentos dikumpulkan dengan menggunakan alat Ekman grab. Hasil penelitian menunjukkan bahwa terdapat korelasi antara indeks keanekaragaman makrozoobentos dengan kontaminasi logam arsen yang tinggi. Kontribusi logam Pb dan Cd dalam memberikan pengaruh pada indeks keanekaragaman relatif masih kecil. Keberadaan makrozoobentos Coleoptera (Simsonia sp.), lintah (Placobdella sp.), larva chironomid (Ablabesmyia sp.), dan (Tanytarsus sp.) relatif toleran dengan kontaminasi logam arsen di sedimen yang tinggi, pH dan suhu yang rendah. Penggunaan indeks keanekaragaman pada penelitian ini masih relatif sensitif dalam mencerminkan gangguan akibat kontaminasi logam berat di sedimen. ABSTRACT Presence of heavy metals in aquatic ecosystems have been reported to cause problems in aquatic organisms. One of the aquatic organisms that have risk for exposure by heavy metals from sediments is macrozoobenthos. This paper aims to describe the influence of heavy metal contamination in sediments to the structure of macrozoobenthos communities in lentic ecosystem (small lakes and reservoirs). This study was conducted in June 2009 to September 2011 in some small lakes and reservoirs which are in West Java and Jakarta provinces. Macrozoobenthos samples were collected by using Ekman grab. The results showed that there is a low correlation index with a high diversity of macrozoobenthos contamination by arsenic. The contribution of Pb and Cd in giving effect to diversity index is relatively small. The existence of macrozoobenthos Coleoptera (Simsonia sp.), Leeches (Placobdella sp.), Chironomid larvae (Ablabesmyia sp.), and (Tanytarsus sp.) relatively tolerant to high contamination arsenic in sediment, and low pH and temperature. The use of diversity index in this study was relatively sensitive to reflect the disruption caused by heavy metal.

Small lakes are understudied compared to medium- and large-sized lakes, but have recently received increased attention due to their abundance and importance for global scale biogeochemical cycles. They have close terrestrial contact, extensive environmental variability, and support high biodiversity among them. Temporal and spatial variability of water temperature, oxygen, and stratification-mixing dynamics were examined during a year in nine small Danish lakes. We found that diel mean surface water temperatures were similar among lakes while the diel range decreased with increasing water depth. Vertical temperature stratification occurred on 47% of the days during the entire year and 64% of summer days, usually with daytime stratification and nocturnal convective mixing. The probability of daytime stratification increased with higher incident irradiance, higher air temperature, and lower wind speed. During spring, daytime stratification caused differences in oxygen saturation between surface and bottom waters. These findings offer new insights on the high variability of water temperature and oxygen in time and space in small temperate shallow lakes. The variable water temperature and the regular stratification-mixing processes will have a pronounced influence on biogeochemical cycles. Also, these features are expected to affect the performance and evolutionary process of organisms associated with small lakes. [ABSTRACT FROM AUTHOR]

More than half of the freshwater lakes in the Philippines are small with surface areas of <2 km 2 . The dynamics in these lakes are different from those in the bigger lakes. This study was conducted to determine the organic pollutants and their sources in three of the seven lakes of San Pablo City in Laguna, Philippines: lakes Palakpakin, Sampaloc, and Pandin. Gas Chromatography-Mass Spectrometry (GC–MS) and Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS) were used in the targeted and non-targeted analysis of the lake water samples. The three lakes are all volcanic crater lakes but are exposed to different anthropogenic activities, which includes domestic activities, livelihood (farming and aquaculture) and eco-tourism. Due to the presence of rice fields and fruit plantations, chlorpyrifos was detected in the three lakes while other pesticides like cypermethrin, picolinafen and quinoxyfen were additionally found in Lake Sampaloc, which is the biggest of the three lakes and located within the urbanized section of the city. Traces of different surfactants (linear alkylbenzene sulfonates, secondary alkyl sulfonates, alkyl sulfates, alkyl ether sulfates), biocide benzalkonium chloride, insect repellent diethyltoluamide, antibiotics (sulfadiazine and sulfamethoxazole), hypertension drug telmisartan, phosphate-based fire retardants, and artificial sweeteners (acesulfame, cyclamate, saccharin and sucralose) were detected in lakes Sampaloc and Palakpakin. The same surfactants, artificial sweeteners, insect repellant and phosphate-based fire retardants were also found in Lake Pandin, which is mainly used for eco-tourism activities like swimming and boating. The results of this study suggest that the organic pollutants present in the small lakes can be linked to the various human activities in the immediate lake environment. Because small lakes are more prone to environmental stresses, human activities in the said lakes must be regulated to ensure sustainable development. [ABSTRACT FROM AUTHOR]

Abstract: Predicting algal blooms has become a priority for scientists, municipalities, businesses, and citizens. Remote sensing offers solutions to the spatial and temporal challenges facing existing lake research and monitoring programs that rely primarily on high‐investment, in situ measurements. Techniques to remotely measure chlorophyll a (chl a) as a proxy for algal biomass have been limited to specific large water bodies in particular seasons and narrow chl a ranges. Thus, a first step toward prediction of algal blooms is generating regionally robust algorithms using in situ and remote sensing data. This study explores the relationship between in‐lake measured chl a data from Maine and New Hampshire, USA lakes and remotely sensed chl a retrieval algorithm outputs. Landsat 8 images were obtained and then processed after required atmospheric and radiometric corrections. Six previously developed algorithms were tested on a regional scale on 11 scenes from 2013 to 2015 covering 192 lakes. The best performing algorithm across data from both states had a 0.16 correlation coefficient (R2) and P ≤ 0.05 when Landsat 8 images within 5 d, and improved to R2 of 0.25 when data from Maine only were used. The strength of the correlation varied with the specificity of the time window in relation to the in‐situ sampling date, explaining up to 27% of the variation in the data across several scenes. Two previously published algorithms using Landsat 8's Bands 1–4 were best correlated with chl a, and for particular late‐summer scenes, they accounted for up to 69% of the variation in in‐situ measurements. A sensitivity analysis revealed that a longer time difference between in situ measurements and the satellite image increased uncertainty in the models, and an effect of the time of year on several indices was demonstrated. A regional model based on the best performing remote sensing algorithm was developed and was validated using independent in situ measurements and satellite images. These results suggest that, despite challenges including seasonal effects and low chl a thresholds, remote sensing could be an effective and accessible regional‐scale tool for chl a monitoring programs in lakes. [ABSTRACT FROM AUTHOR]

The paper summarizes the results of integrated study of current state of freshwater biota of small water bodies, located in the area of ‘Fedorova tundra’ intrusion. A list of species composition is given, quantitative and structural indicators of phytoplankton, zooplankton, zoobenthos and fish are assessed. Size-weight, age and sex structure of dominant ichthyofauna are estimated. The obtained results can be used as the reference values for further monitoring of the ecological status of the water bodies.

Remote sensing of ice phenology for small lakes is hindered by a lack of satellite observations with both high temporal and spatial resolutions. By merging multi-source satellite data over individual lakes, we present a new algorithm that successfully estimates ice freeze and thaw timing for lakes with surface areas as small as 0.13 km2 and obtains consistent results across a range of lake sizes. We have developed an approach for classifying ice pixels based on the red reflectance band of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, with a threshold calibrated against ice fraction from Landsat Fmask over each lake. Using a filter derived from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) surface air temperature product, we removed outliers in the time series of lake ice fraction. The time series of lake ice fraction was then applied to identify lake ice breakup and freezeup dates. Validation results from over 296 lakes in Maine indicate that the satellite-based lake ice timing detection algorithm perform well, with mean absolute error (MAE) of 5.54 days for breakup dates and 7.31 days for freezeup dates. This algorithm can be applied to lakes worldwide, including the nearly two million lakes with surface area between 0.1 and 1 km2.

Interest in Stable Isotopes Analyses (SIA) is increasing in freshwater ecology to better clarify ecosystems’ functioning. By measuring carbon and nitrogen isotopic signatures, food sources and organism trophic levels can be tracked, providing quantitative estimates of bi-dimensional niches. In order to describe some general patterns of carbon and nitrogen stable isotope signatures in lakes, we applied SIA to zooplankton community in five subalpine lakes sampled in spring and summer along a trophic gradient (from oligotrophy to hypereutrophy). Within zooplankton taxa, temporal variation in food sources and trophic levels were compared to find out taxon-specific patterns. Carbon and nitrogen isotopic signatures differed among the five lakes, reflecting depth, topography, and trophic status of the lakes. Carbon isotopic signatures varied more considerably in deeper and larger lakes (Mergozzo and Pusiano) than in a shallower and smaller lake (Lake Endine). Nitrogen isotopic signatures were generally more enriched in lakes Pusiano and Moro than in Lake Mergozzo, whereas in summer, they were depleted in all lakes. These observations indicate that zooplankton taxa specific trophic roles differed among lakes and in time. [ABSTRACT FROM AUTHOR]

Small waterbodies, including ponds and small lakes, low-order streams, ditches and springs, are the most numerous freshwater environments globally, are critical for freshwater biodiversity and are increasingly recognised for their role in ecosystem service delivery. Small waters often represent the best remaining examples of intact freshwater habitats and are the most likely to remain unpolluted, often being a refuge for species which have disappeared from larger, more damaged, waterbodies. Practically all water-related ecosystem services are initially mediated by small waters and some, such as carbon cycling, may be dominated by them. Small waters are exposed to all the threats affecting larger waters, and some experienced only by small waters. Despite this, small waters remain the least investigated part of the water environment and are largely excluded from water management planning. We identify the priorities for research to underpin better protection of small waters and recommend policy actions needed to better integrate small waters into the management of catchments and landscapes. The primary requirements are to identify reliable monitoring programmes for small waters, develop effective measures to protect the biodiversity and ecosystem services they provide and ensure that regulators take full account of this critical part of the water environment. [ABSTRACT FROM AUTHOR]

The seasonal dynamics of freshwater lake ice and its interactions with air and snow are studied in two small subarctic lakes with comparable surface areas but contrasting depths (4.3 versus 91 m). Two, 2.9 m long thermistor chain sensors (Snow and Ice Mass Balance Apparatuses), were used to remotely measure air, snow, ice, and water temperatures every 15-min between December 2021 and March 2022. Results showed that freeze-up occurred later in the deeper lake (Ryan Lake) and earlier in the shallow lake (Landing Lake). Ice growth was significantly faster in Ryan Lake than in Landing Lake, due to cold water temperatures (mean (T w ¯) =0.65 to 0.96°C) persisting beneath the ice. In Landing Lake, basal ice growth was hindered because of warm water temperatures (T w ¯ =1.5 to 2.1°C) caused by heat released from lake sediments. Variability in air temperatures at both lakes had significant influences on the thermal regimes of ice and snow, particularly in Ryan Lake, where ice temperatures were more sensitive to rapid changes in air temperatures. This finding suggests that conductive heat transfer through the air-water continuum may be more sensitive to variability in air temperatures in deeper lakes with colder water temperatures than in shallow lakes with warmer water temperatures, if snow depths and densities are comparable. This study highlights the significance of lake morphology and rapid air temperature variability on influencing ice growth processes. Conclusions drawn aim to improve the representation of ice growth processes in regional and global climate models, and to improve ice safety for northern communities. • Two autonomous ice sensors were deployed in two Canadian subarctic lakes. • Air, snow, ice, and water temperatures measured at 15-min intervals for 4 months. • Ice temperatures were more sensitive to variable air temperatures in the deep lake. • Ice growth in shallow lake was inhibited by heat released from lake sediments. • Small lakes may act as significant regional sources of conductive heat. [ABSTRACT FROM AUTHOR]

Stable isotopes offer an opportunity to investigate lake dynamics in the absence of whole catchment studies. This study considered multi-year δ18O values for six different lakes located in the Italian Alps. We studied δ18O values of two large (L. Caldonazzo and L. Levico) and four small lakes (L. Lavarone, L. Santo di Cembra, L. Serraia, and L. Tovel) characterised by different hydrological regimes (> or or