Summer Stagnation Research Articles

No trophy for the trophy? - How lake trophy impacts bacterial assemblages of biofilm on microplastic

The composition of biofilm formed on artificial microplastics (MPs) during the summer stagnation was studied in a field experiment at five lakes with different trophy. After a two-month incubation of MPs, molecular analyses were carried out to isolate the genetic material of bacteria present in the biofilm. Next-generation sequencing of 16S rRNA genes was performed to identify species. Bacterial abundance was also determined in the lake water (2.31 – 4.26 Mcell ml−1) and in the water from experimental baskets containing MPs (0.58 – 4.68 Mcell ml−1). The biofilm formed on the MPs was analysed at various systematic levels, including phylum, family, class, genus, and species. A total of 18 species were identified, with a high percentage of the Proteobacteria phylum noted. This may indicate that this group favours MPs regardless of the trophic level. In this study, the presence of bacteria with the ability to degrade polymers, such as Pseudomonas putida, was observed, as well as Lacibacterium aquatile, which can indicate water quality. Among the other identified bacterial species, several pathogens were found, including Escherichia coli, Staphylococcus aureus, Candidatus Saccharibacteria, and Candidatus Cardinium, which may indicate anthropogenic pollution. The presence of E. coli was detected on MPs in each of the studied lakes, suggesting that MPs may serve as a new vector for dangerous pathogens, regardless of trophic status. Despite the two-month experiment, no statistically significant differences in bacterial species diversity (as measured by alpha and beta indices) were observed between lakes with different trophy.

Attributing the drivers of runoff decline in the Thaya river basin

Study Region:The Thaya river basin provides multiple water uses in the transboundary region of Lower Austria and Southern Moravia. Due to the low precipitation (P) to reference evapotranspiration (ETo) ratio, the Thaya river basin is among the most sensitive to climate change in the region. Study Focus:The main objective is to understand the changes in the water balance variables including actual evapotranspiration (ET), P and runoff (RO) and their drivers for the period 1981–2020, and 2001–2020 in the case of using remote sensing data. New Hydrological Insights for the Region:The analyses confirm previously reported increasing trends in air temperature, ETo, and no trends in P. ET consistently increased during spring and decreased during summer, although insignificantly. This change was associated with a significant increase of spring vegetation development followed by summer stagnation. The spring RO shows significantly decreasing trends, especially in the upland water source areas. The correlation analysis reveals a different behavior along the altitude gradient, with ET in the uplands generally limited by available energy whilst in the lowlands by available water in spring. In summer, however, the entire basin is often water-limited, with a more pronounced limitation in the lowlands. Complex adaptation measures reflecting the different hydroclimate relations across the altitudinal gradient are needed to sustain the water dependent sectors operating in the region facing increasing aridity.

Litter per liter – Lakes' morphology and shoreline urbanization index as factors of microplastic pollution: Study of 30 lakes in NE Poland

Human activity and anthropopression play key roles in contaminating aquatic environments with microplastics (MPs). The lakes of northeastern Poland provide a wide range of freshwater ecosystems differing in morphology, hydrology and ecology. In this study, we investigate 30 lakes during summer stagnation, considering their varying levels of anthropogenization of the catchment area and taking into account increased tourist activity. MPs were found in each of the studied lakes in the range from 0.27 MPs/L to 1.57 MPs/L, and the average value was 0.78 ± 0.42 MPs/L. The features of the MPs were evaluated, including size, form and color (most frequent: 4–5 mm (35.0 %); fragments (36.7 %); blue (30.6 %), respectively). Gradual accumulation of MPs has been observed in the lakes that comprise the hydrological sequence. The amount of sewage produced by wastewater treatment plants was considered in the study area. Statistically significant differences were found between lakes with different surface areas and shoreline lengths, where lakes with the highest and smallest values were notably more polluted with MPs than lakes in the medium range (F = 34.64, p < .0001 and F = 5.96, p < .01, respectively). The study presents an easy-to-obtain shoreline urbanization index (SUI) that is particularly useful for lakes with heavily transformed catchments in terms of hydrology. A significant correlation between the MP concentration and SUI, reflecting the degree of direct catchment anthropopression (r = +0.4282; p < .05), was observed. The analysis of the human impact on shoreline conversions and development should also pique the interest of other researchers as a potential indicator of MP pollution.

Long term changes in the quality and water trophy of Lake Ińsko – the effect of the re-oligotrophication?

In 1970–2010, during the period of spring circulation and summer stagnation, hydrochemical studies were conducted in Lake Ińsko (Western Pomeranian Lake Region, Poland) with determination of the lake susceptibility to degradation and trophic changes. Also, the effect of the catchment area on the water quality in this waterbody was assessed. The waters of the study lake were characterised by low static index, which is an additional indicator of low dynamics of water masses, and low susceptibility to degradation. In spite of this, significant changes in the lake quality and trophy were observed. The hydrochemical parameters defining water quality of the study lake continued to improve. In the 70’s, the water quality was at the border of class II and III, while in 2006 and 2010 it reached the level characteristic for class I waters. Moreover, in the 70’s and 80’s of the previous century, Lake Ińsko Duże was a mesotrophic lake. Then, an increase in the lake trophy was observed, resulting in signs of eutrophy. At the end of the 90’s and in the first decade of the 21st century, the study lake returned to the state of mesotrophy. No restoration works were undertaken in Lake Ińsko in the study period. The improvement in water quality, called oligotrophication, resulted most probably from the lake reaction to changes in the soil use in the catchment area, since fewer phosphorus and nitrogen compounds flow into the lake, and also from the regulation of the wastewater management in the town of Ińsko.

Permanent Thermal and Chemical Stratification in a Restored Urban Meromictic Lake

Meromictic lakes are unique aquatic ecosystems that occur extremely rarely. The phenomenon of meromixis can result from both natural and anthropogenic factors. The aim of this study was to analyse thermal and chemical stratification in a small, deep (6 ha, H max = 24.5 m) lake. The evaluated lake had a typical summer thermal profile with a shallow epilimnion, a sharp thermocline, and a distinct monimolimnion layer in the hypolimnion, which was also maintained during circulation. The lake had a clinograde oxygen profile, with an oxygen deficit in the metalimnion and permanent anoxic conditions in the deeper layers, including during circulation. A redox zone was identified during summer stagnation. The monimolimnion formed a thermally isolated layer at a depth of around 15 m, and the chemocline was situated above the monimolimnion. In the chemocline, the EC gradient ranged from 61 to 77 μS·cm−1 per meter of depth in the summer and from 90 to 130 μS·cm−1 per meter of depth during circulation. EC was significantly correlated with Ca2+ concentration (r2 = 0.549). Chemical stratification, particularly with regard to organic matter distribution, was observed in the chemocline. The monimolimnion severely limited nutrient internal loading.

Transfer efficiency of carbon, nutrients, and polyunsaturated fatty acids in planktonic food webs under different environmental conditions.

The trophic transfer efficiency (TTE) is an important indicator of ecosystem functioning. However, TTE data from freshwater food webs are ambiguous due to differences in time scales and methods. We investigated the transfer of essential substances (carbon, nutrients, and polyunsaturated fatty acids) through plankton communities in 30 Polish lakes with different trophic status in the middle of summer. The results of our study revealed that different essential substances were transferred from phytoplankton to zooplankton with varying efficiencies. The average TTE of C, N, P, and the sum of ω‐3 PUFA were 6.55%, 9.82%, 15.82%, and 20.90%, respectively. Our results also show a large mismatch between the elemental and biochemical compositions of zooplankton and their food during the peak of the summer stagnation, which may further promote the accumulation of essential substances. There were also large differences in TTEs between trophic conditions, with the highest efficiencies in oligotrophic lakes and the lowest in dystrophic and eutrophic lakes. Therefore, our study indicates that disturbances like eutrophication and dystrophication similarly decrease the TTE of essential substances between phytoplankton and zooplankton in freshwater food webs.

How the integrated engineering solutions can support the lakes restoration?

ABSTRACT A method of the simultaneous reduction of external and internal load of phosphorus as a new solution for lake restoration is presented. A flow-through, stratified lake, with diverse morphometry was selected for the study. In all three parts of the lake, an oxygen deficit was noted at the lake bottom at peak summer stagnation, with a simultaneous increase in mineral forms of phosphorus (the concentration of orthophosphates at sites I, II and III reached 0.301, 0.318 and 0.395 mg P l−1, respectively). Additionally, a large load of nutrients originating from the main inflow (annual load of 14395.9 kg P y−1 and 16 4829.8 kg N y−1), indicates that the conditions present in the lake are conducive to more intensive eutrophication. In this situation, reduction of the main loads of nutrients can be achieved by the simultaneous employment of pipelines delivering oxygenated water to the lake bottom during summer stagnation and a pipeline withdrawing deoxygenated and nutrient-rich water from the bottom in the vicinity of the outflow from the lake. It has been calculated that during the period of summer stagnation (VI-IX), the operation of delivering pipelines can reduce the phosphorus load from the main inflow by 5800.5 kg (40.3%). Using the pipeline withdrawing (site III), the amount of phosphorus removed from the lake would increase by 30.4% (from 2259.6 kg to 3247.8 kg). An additional solution, can be dosing the precipitating substances into the pipes delivering water to the lake, which will enable precise inactivation of phosphorus.

Thermal Structure of Water During the Summer in Lakes of the Polish Lowlands as a Result of their Varied Morphometry

Abstract The paper discusses the impact of lake morphometric parameters on the thermal structure of water during the period of summer stagnation. The summer period in the lakes is characterized by clearly expressed properties of the thermal structure of water, differentiating lakes from one another. The study was carried out on 141 lakes in northern Poland, for which at least 3 vertical water temperature measurements were taken in different years. They showed a significant influence of lake basin morphometry upon the thermal structure of water in lakes. In general, measurements of the vertical distribution of water temperature showed clear diversity, and depending on the depth also thermal layers (epi-, meta- and hypolimnion). The results of the analysis of 8 lake morphometric parameters and 10 thermal stratification parameters revealed the existence of significant dependencies between them. The best-preserved relations (statistically significant) occurred between the parameters characterizing the lake depth and meta- and hypolimnion properties, as well as the thermal stratification factor and heat content in a unit of volume.

Managing climate change in drinking water reservoirs: potentials and limitations of dynamic withdrawal strategies

BackgroundClimate change induced a rise in surface water temperature and a prolongation of summer stratification in drinking water reservoirs. Stratification and temperature are important factors for drinking water production because they influence bio-geo-chemical processes and thus affect water quality. Most drinking water reservoirs have outlet structures that allow water to be withdrawn from different depths at variable rates. The thermal structure of these reservoirs can thus be managed actively by means of dynamic withdrawal schemes.ResultsWe employed the hydro-physical General Lake Model to simulate the effects of different withdrawal strategies on temperatures and stratification in three German reservoirs. In particular, we assessed the potential of depth- and time-variable withdrawal to mitigate the impacts of climate change. We found that deep water temperatures (25 m below surface) and the end of summer stagnation are strongly controlled by the withdrawal regime. Specifically, the simulated impact of the withdrawal scheme was of the same order of magnitude as the observed impact of climate change over the last 30 years. However, the end of ice cover, the onset of summer stagnation, and near-surface temperatures (3 m depth) were rather insensitive to altered withdrawal strategies.ConclusionsOur results suggest that an adaption of withdrawal depth and timing will partly compensate for the effects of climate change. Dynamic withdrawal should thus be considered as an integral part of future reservoir management strategies.

Concentrations of some heavy metal and macroelements in sediment, water, macrophyte species, and leech (Hirudo sulukii n. sp.) from the Kara Lake, Adiyaman, Turkey.

Content of some heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and macroelements (Ca, Mg, Na, and K) were determined in samples of water, sediment, macrophytes (Potamogeton crispus, Potamogeton perfoliatus, Myriophyllum spicatum, and Chara vulgaris), and leech (Hirudo sulukii n. sp.) collected from Kara Lake Adiyaman, Turkey at four distinct seasons using inductively coupled plasma optical emission spectrometer (ICP-OES). It was found that the studied heavy metals were completely below the detection limit of ICP-OES for water samples. The results showed that most heavy metals (Ni, Cr, Zn, Fe, and Pb) and macroelements (Mg and Na) had their highest values in sediment samples in August. Increases of heavy metals and macroelements may be due to evaporation because of summer stagnation at this period. The average content of studied elements was in the order of Mn>Ni>Cr>Zn>Fe>Pb>Cu in sediment samples. As a non-essential heavy metal, Cr was the most accumulated in all the macrophytes studied. The average Cr concentration was in the order of P. crispus > P. perfoliatus > M. spicatum > C. vulgaris. In C. vulgaris, the accumulation of Ca was the highest compared with other macrophytes. The accumulation of heavy metal was in the order of Fe>Zn>Cu>Pb>Mn>Cr>Ni>Cd in H. sulukii n. sp. The obtained results showed that the heavy metal and macroelement (Na, Ca, Mg, and K) concentrations in water, sediment, macrophytes, and leech are below the risk values according to the aquatic life pollutant data provided by the U.S. Environmental Protection Agency. Overall, the element contents can be attributable to the geological sources because of the general absence of serious pollution in Kara Lake, Adiyaman, Turkey.

Vertical distribution of the relic species Eurytemora lacustris (Copepoda, Calanoida) in stratified mesotrophic lakes

The aim of this study was to determine factors affecting the vertical distribution of Eurytemora lacustris in mesotrophic lakes (Wigry, Hańcza, Szurpiły; north-eastern Poland) during the summer stagnation. Eurytemora lacustris was found in all of the studied lakes, with the highest abundance (8 ind. L−1) in Lake Wigry. In Lake Szurpiły, E. lacustris has never been recorded before. The results of this study revealed that E. lacustris was most numerous in thermocline zones, suggesting that this species could temporarily tolerate warmer water and lower oxygen concentrations due to better food resources. During the study, it was found that a large part of the E. lacustris population had epibiont ciliates, in contrast to other species of zooplankton that did not have any epibionts. The improvement in the water quality of many deep lakes could lead to an increase in the abundance of E. lacustris. However, epibiont ciliates may be a threat for this species and may play a substantial role in determining the production, distribution, and community dynamics of E. lacustris.

Present-day state and permissible

The quality of water in Lake Peipus (Pskov-Chudskoye) is described according to data from long-term monitoring. The lake tends to be of the eutrophic type, with turbid water and oxygen deficiency in near-bottom water layers during winter and summer stagnation. Permissible nutrient loadings on the lake were defined according to its assimilating capacity. Current phosphorus and nitrogen loadings are above the permissible levels, and P and N supply from point and non-point sources needs to be reduced.

Thermal and Oxygen Conditions of Lake Charzykowskie in the Years 2014-2016

Abstract This paper presents an analysis of thermal and oxygen conditions of the Charzykowskie Lake in the years 2014-2016 in the period from May to August. The measurements were carried out once a month, at points representing three different basins in the lake, and the temperatures and oxygen content dissolved in the water were recorded every 1m from the surface to the bottom at the deepest point of each basin. The changes in temperatures and content of dissolved oxygen were analysed in each of the representative measurement points for particular parts of the lake. It has been shown that the deficit of oxygen dissolved in the bottom layers of the water starts occurring by the beginning of the summer stagnation period, whereas at its peak (August) the anaerobic zone includes hypolimnion and part of the metalimnion. The hypothesis that the thickness of the thermal layers varies within the lake basin was confirmed. It was also shown that the oxygen content curve at representative points, in all years of research, evolves to the form of a clinograde at the peak of summer stagnation, where the concentration of dissolved oxygen decreases with the depth.

Optical characteristic of humic acids from lake sediments by excitation-emission matrix fluorescence with PARAFAC model

PurposeThe study aimed to find out whether fluorescence parameters of humic acids (HA), obtained from excitation-emission matrix (EEM) fluorescence spectra, could be used to explain the origin and properties of lake sediments organic matter.Materials and methodsThe research material was HA extracted from lake sediments. Sediment samples were collected in the summer stagnation, from maximum depth of each lake. Humic acids extraction was performed using the method proposed by the International Humic Substances Society. In extracted HA, the elemental composition, free radical content, UV-Vis, and EEM fluorescence spectra were determined. EEM spectral modeling was performed using a multidirectional statistical method—parallel factor analysis PARAFAC.Results and discussionFour specific, two protein-like (C2 and C4) and humic- and fulvic-like (C1 and C3) components, components responsible for emission of fluorescence were identified in HA extracted from lake sediments. In the obtained EEM spectra, the dominant component was C2, while the smallest participation have C4 component. The mean contribution of C3 and C1 components to the total intensity of fluorescence was almost the same and was about 25%. Significant correlations were obtained between the concentration of EEM components and parameters characterizing the chemical properties of sediments and humic acids.ConclusionsThe study showed that the EEM fluorescence spectroscopy can be successfully used to characterize natural organic matter in aquatic environments. This method may provide supplementary information on the origin and transformation of organic matter in the water environments. By applying the parameters obtained from PARAFAC modeling, the relative degree of organic matter transformation (component C1) and autotrophic productivity (component C3) may be assessed. The analysis of the component C1 and C4 complete the information about the organic matter origin.

Is unstable reliable? Oxygen conditions in the ecological status assessment of lakes

Abstract The Water Framework Directive introduces the requirement for ecological status assessment based primarily on aquatic organisms and supporting physico-chemical elements, including oxygen conditions. The criteria for assessing oxygen conditions applied in routine lake monitoring in Poland are based on the mean hypolimnetic saturation with oxygen at the peak of summer stagnation in stratified lakes, and on the oxygen content at the bottom in the summer in polimictic lakes. The currently used oxygen criteria usually cause dismay, particularly if biological elements indicate at least good ecological status and the oxygen conditions are the only reason for lowering status class. The aim of the article is to present the scale of variability of oxygen conditions in selected lakes within the last two decades and to analyse the limitations and conditions of applying this indicator in routine monitoring, assessment and classification of Polish lakes. Data from the years 1999–2015 on oxygen and thermal conditions in a set of nine benchmark lakes in Poland were examined and the reasons for changeability in water oxygenation from year to year were discussed. Alternative oxygen indicators were considered as well as oxygen standards based on fish protection requirements that have been adopted in some European countries. It was suggested that when assessing lake ecological status, data on the oxygen conditions from a number of years must be taken into consideration, e.g., for the analysis of trends in lake trophy changes or for documenting the effects of remedial actions in lake catchment areas in long time frames.

THE OXYGEN REGIME OF A SHALLOW LAKE

The year-round measurement data of water temperature and dissolved oxygen content in a small boreal Lake Vendyurskoe in 2007–2013 were used to explore the hydrophysical prerequisits of anoxia and accumulation and emission of greenhouse gases. Typically, anoxia appears in the bottom layers of lakes in mid-winter and during the summer stagnation. The thickness of the benthic anaerobic zone (dissolved oxygen concentration &lt;2 mg·l–1) reached one meter in the end of the winter and at the peak of the summer stratification, except for the extremely hot summer of 2010, when it reached five meters. Synoptic conditions had a crucial influence on the formation and destruction of the benthic anaerobic zones in summer. The most favorable oxygen dynamics was observed during the cold summers of 2008, 2009, and 2012, when the repeated full mixings of the water column occurred under conditions of the cyclonic weather. In the winter periods, the early dates of ice season resulted in the most pronounced deficiency of oxygen.

The effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour

&lt;p&gt;The objective of this study was to evaluate the effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour in the vicinity of the pipeline outlet. The study was carried out in 2012-2013 from the beginning of the summer stagnation period in Lake Kortowskie to complete overturn in fall. Samples of river water and ambient air were collected from two sites: near the pipeline outlet (PO) and behind the academic campus (AC). A total of 44 air samples and 44 water samples were analysed. Odour intensity was measured in samples of ambient air. The following physicochemical parameters of water were determined: flow rate, dissolved oxygen (DO), hydrogen sulphide (H&lt;sub&gt;2&lt;/sub&gt;S), sulphate (SO&lt;sub&gt;4&lt;/sub&gt;), ammonium nitrogen (NH&lt;sub&gt;4&lt;/sub&gt;-N), total nitrogen (TN), dissolved nitrogen (DN), total particulate nitrogen (T-PN), total organic carbon (TOC), dissolved organic carbon (DOC) and total particulate organic carbon (T-POC). Water samples were also analysed to determine total bacterial abundance (TBA) and the counts of bacterial rods, cocci and spiral-shaped bacteria, and sulphate-reducing bacteria (SRB). Significant variations in odour intensity were noted between years and sampling sites. Odour was significantly determined by the proportion of lake water in river water. It was also significantly correlated (P&amp;lt;0.01, P&amp;lt;0.001) with most of the analysed physicochemical and microbiological parameters. The multiple regression analysis revealed that odour intensity was influenced directly by TOC and DN and indirectly by H&lt;sub&gt;2&lt;/sub&gt;S, NH&lt;sub&gt;4&lt;/sub&gt;-N, TBA and counts of SRB, rod- and spiral-shaped bacteria only in.&lt;/p&gt;

Variation of nitrogen forms in lakes with different intensity of anthropogenic pressure

AbstractThe aim of this study was to compare the concentration of nitrogen and trace the dynamics of its changes in two lakes with different intensity of anthropogenic pressure. The dominant land use of Lake Paskierz catchment is built-up areas, while in Lake Sajmino, wasteland is the dominant land use. The total amount of nitrogen in Lake Paskierz ranged from 1.68 to 6.58 g Ntot m-3, while in Lake Sajmino it was from 1.03 to 1.84 g Ntot m-3. The organic fraction was a dominant form in the surface water layers of the examined lakes. A slightly different situation was found in near-bottom water layers of Lake Paskierz, where ammonium nitrogen was the dominant form in the summer stagnation. In other cases organic nitrogen was a dominant form in each of the reservoirs. Concentrations of nitrites and nitrates were low and did not affect essentially the overall amount of nitrogen in the studied lakes. Based on the results, it can be concluded that Lake Paskierz is overfertilized. The high concentrations of ammonia measured in near-bottom layers of the lake indicate that the internal supply may be a very important process affecting the trophic status. Lake Sajmino was characterized by significantly less nitrogen abundance, although the periodically increasing nitrogen concentration reveals the presence of adverse anthropopressure on the lake.

Evaluation of Chemical and Physico-Chemical Indicators of Water and Bottom Macrofauna the Resko Lake on the Basis of the European Union Water Framework Directive

Have studied lake close to neutral pH – 7.67 to 7.73. All lakes in accordance with the classification of the European Union Water Framework Directive have been included in the first class.The concentration in the surface layer of Ptot. Lake is little differentiated, is at level II quality class according to the classification of the European Union Water Framework Directive. Tested water lakes were changing the concentration of the PO43-sdiss - these concentrations correspond to water quality from III. The increase of the concentrations of phosphorus in the Lake may indicate a decrease in the amount of oxygen in the waters of the shallow and changes their status to release phosphorus compounds accumulated redox in sediment bottom. In the case of nitrogen-compounds nitrates and nitrites values for these indicators were at level I and II class in all the surveyed lakes in accordance with the classification of the European Union Water Framework Directive. Indicator, which indicates the high productivity of Lake is the biochemical oxygen demand (BOD5). The level of this indicator values on the studied Lake was on level III class. In the remaining Lake oxygen concentration was similar (continued in I class). Fauna of the Resko Lake bottom during summer stagnation was poor in terms of quality, which proves its considerable biological degradation. In terms of the concentration in the test macrozoobenthos Lake dominated, and Oligochaeta, Diptera larvae.

The infrared camera: a tool for mountain lakes research

AbstractDuring field research work an attempt was made to use an infrared camera in alpine conditions without the use of a plane. The images received as thermal pictures are of high value because they show a continuous record of temperature on the whole water surface. The scale of temperature diversity is very high and amounts to approximately 6°C. It is necessary to take photos of this type at short time intervals. It will enable the circulation of waters which results in a change in water temperature to be captured. This research will also allow seasonal changes of water temperature to be seized, for example during summer stagnation, water freezing, destruction of the ice layer and also the influence of the coastal zone on shaping thermal conditions in the zone of coastal waters.