Metrics details Water transparency affects the thermal structure of lakes and within certain lake depth ranges it can determine whether a lake mixes regularly (polymictic regime) or stratifies continuously (dimictic regime) from spring through summer Phytoplankton biomass can influence transparency but the effect of its seasonal pattern on stratification is unknown Therefore we analysed long term field data from two lakes of similar depth transparency and climate but one polymictic and one dimictic and simulated a conceptual lake with a hydrodynamic model Transparency in the study lakes was typically low during spring and summer blooms and high in between during the clear water phase (CWP) caused when zooplankton graze the spring bloom The effect of variability of transparency on thermal structure was stronger at intermediate transparency and stronger during a critical window in spring when the rate of lake warming is highest Whereas the spring bloom strengthened stratification in spring The presence or absence of the CWP influenced stratification duration and under some conditions determined the mixing regime including biotic interactions that suppress the CWP stratification duration and potentially also the mixing regime They unequivocally conclude that a reduction in transparency decreases deep water temperatures the thickness of the surface (mixed) layer and the overall heat content of the water body The increased temperature difference between surface and deep water stabilises thermal stratification the vast majority of these studies deals with deep seasonally stratified lakes and relatively little is known about how transparency affects marginal lakes the effect of the distinct seasonal pattern of transparency resulting from phytoplankton biomass on thermal structure and stratification duration Our hydrodynamic model simulations were performed with an idealized seasonal phytoplankton pattern in a conceptual lake where the only lake-specific parameters were light extinction coefficient (γ) thus focusing on general phenomena rather than lake-specific detail We hypothesize that seasonal phytoplankton dynamics and the CWP affect the stratification duration thermal structure and potentially the mixing regime of temperate marginal lakes Dependence of extinction (γ) on chlorophyll a and dissolved organic carbon (DOC) concentration in Müggelsee (a,b) and Heiligensee (c,d) γ was calculated from Secchi transparency (Zsecchi) with equation 3 using c = 2.05 for Müggelsee and c = 2.13 for Heiligensee (see Methods) chla is the chlorophyll concentration (μg L−1) and DOC is in mg L−1 light absorption through phytoplankton was the main driver of transparency in the study lakes Mean seasonal pattern of chlorophyll a (Chla (c,d)) and stratification strength (Ts − Tb (e,f)) in Müggelsee (a,c,e) and Heiligensee (b,d,f) lines with symbols show how the first (b,c,d,f) or second principal component (e) affect the mean seasonal pattern Open symbols show a low score of the respective principal component (25th percentile in the time series) and closed symbols show a high score (75th percentile) Seasonal patterns represented by like symbols in each lake are correlated The scores for Chla in Müggelsee are not shown because they were not correlated with Zsecchi or Ts − Tb; instead the shaded region in (a) represents 1 standard deviation from the mean Note reversed y-scale for Zsecchi reflecting depth measured downwards Monthly loadings of the first two components (PC1 PC2) from the principal component analysis of inverse-transformed chlorophyll a (Chla−1 Both lakes were on average isothermal and unstratified from October to March as reflected in near zero values of the mean difference between surface and bottom temperatures (Ts − Tb, neglecting inverse stratification in winter and noting that negative values were truncated; Fig. 2e,f) peaking in July at 1.6 °C and 8.1 °C in Müggelsee and Heiligensee PC2 on the other hand had the highest absolute loading in April in both lakes and mainly represented variation in spring stratification relative to summer We assessed synchrony between the two lakes by comparing the deseasonalised (centred) monthly means of Ts − Tb and Secchi transparency in the two lakes during the period of parallel measurements (1979–2000) considering only the potentially stratified months of April to August df = 93) were significantly correlated in the two lakes Monthly chlorophyll concentrations did correlate between the lakes however (p = 0.008 at least during the years when parallel measurements existed (1991–2000) We further checked the principal components for synchrony PC1 for Secchi transparency was not correlated between the lakes (p = 0.10) nor was PC2 for Ts − Tb in Müggelsee correlated with PC1 for Ts − Tb in Heiligensee (p = 0.55) nor were the PCs for chlorophyll correlated (p = 0.72) Thus transparency and stratification were correlated within each lake but in a way that was not synchronous between the lakes a stronger seasonal amplitude of transparency and a more intense CWP significantly weakened summer stratification and skewed temperature gradients away from summer towards spring in both lakes This response was independent of whether the lake was polymictic or dimictic Seasonal extinction scenarios used in model simulations The base seasonal extinction pattern (black line in (a,b)) was defined based on long term measured extinction in Müggelsee (grey lines in (a) each line representing one year) and Heiligensee (grey lines in (b)) Extinction scenarios were then derived from the base extinction pattern by varying annual mean extinction with a clear water phase (CWP (c)) and without a CWP (d) or by varying the timing of the spring bloom (e) Seasonally variable extinction scenarios were compared with control scenarios of constant extinction (f) Model validation against measured temperatures and stratification in Müggelsee (a,c) and Heiligensee (b,d) open orange symbols show surface temperatures closed blue symbols show surface-bottom temperature differences (a) or bottom temperatures (b) Lines show the corresponding simulated temperatures vertical bars show the observed (orange) and modelled (blue) total number of stratified days per year Error bars in (d) were estimated from the sampling interval We used the period 2004–2009 in (c) for Müggelsee because high frequency temperature profiles were available only after 2004 The model was parameterised for a conceptual lake similar to both Müggelsee and Heiligensee It was run with the same meteorological forcing for both lakes with the exception of a 50% increase in wind speed for Müggelsee Simulated effect of annual mean extinction, on mean lake thermal properties under constant extinction or variable extinction scenarios with and without clear water phase (CWP) Grey dashed lines denote a transitional region between polymixis and dimixis at Dur = 120 days The lake becomes dimictic at higher extinction when the CWP is present than when it is absent Seasonally variable extinction produced striking effects on thermal structure in the transitional range of 0.5–1.5 m−1. Variable extinction with a CWP weakened thermal gradients and stratification compared to constant extinction within the range  = 0.6–1.0 m−1, as evident from higher Tb and shorter stratification (Fig. 6) temperature gradients and stratification duration were considerably higher at the same across the whole transitional range (0.5–1.5 m−1) at  = 0.7 m−1 mean Tb was 1 °C lower and stratification duration was on average 49 days longer when the CWP was absent than when it was present the presence or absence of the CWP determined whether the lake was dimictic or polymictic Seasonal development of mean simulated lake thermal characteristics comparing constant extinction (dashed lines) and seasonally variable extinction scenarios with a clear water phase (CWP = 0.7 m−1 (a,b,c) or 1.0 m−1 (d,e,f)) and without a CWP (dot-dashed lines Scenarios with variable spring bloom timing showed that a delay in spring bloom timing from day 90 to day 120 (approximate range observed in Lake Müggelsee) increased thermal stability of the water column slightly as evident in higher Ts − Tb beginning near the spring bloom and persisting as long as Ts − Tb was positive Bloom timing had little effect on Ts or overall stratification duration Effect of a short term deviation in extinction at different times of year on the annual mean difference between surface (Ts) and bottom temperature (Tb) (c,d) The deviation was created by doubling (a) or halving (b) a constant arbitrary baseline extinction (1.0 m−1) for 20 days Simulations were performed with the deviation midpoint shifted to different days of the year Sensitivity of mixing regime to mean extinction () mean lake depth (Zmean) and the clear water phase (CWP) for a lake with 1000 m fetch similar to Heiligensee (a) and for a lake with 4000 m fetch and increased wind speed by 50% The shaded area represents the region that is on average only polymictic when the CWP is present delineating the transitional conditions under which lakes shifted between polymictic and dimictic regimes in at least 10% of simulated years The circles marked “M” and “H” show the average observed conditions in Müggelsee and Heiligensee We demonstrated that stratification duration and the mixing regime of marginal lakes may respond strongly to seasonal changes in phytoplankton biomass Our study showed that cardinal planktonic events in spring potentially have a large influence because they fall within a critical window during which transparency has a much stronger effect than at other times of the year The model simulations indicated the existence of certain depth and extinction combinations where the presence or absence of the CWP altered the average mixing regime The empirical results demonstrated that a stronger seasonal pattern associated with a more intense CWP decreased summer stratification relative to spring We therefore confirm our hypothesis that seasonal phytoplankton dynamics and the CWP significantly affect the stratification duration thermal structure and mixing regime of temperate marginal lakes which does not seem to be the case in deep dimictic temperate lakes Our results are in line with these conclusions and suggest that the effect of transparency is a lot stronger in marginal lakes because its seasonal variability has a greater effect in the range between stable polymixis and stable dimixis Thus we conclude that not only the annual mean transparency but also the seasonal variation in transparency and the CWP play an important role This is not surprising for marginal lakes because by definition the mean lake depth is similar to the thermocline depth so there is most likely an interaction between stratification and bloom formation This interaction makes it difficult to infer causality from field data to help interpret whether phytoplankton-mediated changes in transparency also alter stratification The model simulations of the conceptual lake indicated that a more intense CWP compared to constant extinction weakens summer stratification relative to spring under both weak stratification (summer Ts − Tb ~ 0–5 °C) and stronger stratification (summer Ts − Tb ~ 5–10 °C) as observed in Müggelsee and Heiligensee we did not detect any significant synchrony in the correlated principal components between the two lakes suggesting that internal dynamics might have a stronger influence than regional climate in addition to the well-known effects of stratification on bloom formation seasonal variability of transparency through phytoplankton also significantly influences stratification in marginal lakes regardless of whether predominantly polymictic or seasonally stratified which explains why the CWP and spring bloom have such a strong effect on thermal structure This was clearly evident in the statistical analysis of Müggelsee and Heiligensee where a smaller spring bloom and clearer CWP weakened summer stratification relative to spring The simulations with the conceptual lake reproduced this stratification response to seasonal transparency delivering an explanation for this behaviour Whereas the spring bloom initially strengthens stratification the CWP reduces vertical temperature differences by allowing radiation to penetrate to and heat deeper water layers and thus potentially alter the mixing regime The importance of the CWP and the weather conditions during the spring critical window also explains the anomaly in the model validation against the stratification duration observed in Müggelsee in 2008 (Fig. 5c) 2008 had the highest mean global radiation the third highest mean air temperature and the lowest mean wind speed in the 30 year data period using a standard extinction scenario in the validation the model predicted strong stratification in Müggelsee beginning in late April which was stable enough to persist into summer Whereas this led to a long period of stratification in the simulation the observed stratification duration in Müggelsee was considerably shorter strong stratification also developed in late April but had disappeared again by mid June The reason is likely that the CWP in May 2008 (mean Secchi depth 4.1 m) was one of the most intense in the 35 year record being only exceeded in May 1998 (mean Secchi depth 4.5 m) Therefore biotic interactions may accelerate the mixing regime shifts in temperate marginal lakes expected due to climate change DOC was measured by non-dispersive infrared sensing after combustion with an N/C analyser (Shimadzu in Heiligensee or a Jena Analytics multi N/C 2100 in Müggelsee) γ was reconstructed for 1975–2001 from the longer Secchi depth time series FLake indirectly assumes the lake to have a constant cross-sectional area and flat bottom (maximum depth is equal to the mean depth) the bottom temperature in FLake is the temperature in a hypothetical lake of regular form with the same area and volume as the real lake The result of this simplification is the possibility to apply the self-similarity approach to the temperature profile and an enormous increase of computational speed (FLake is at least 102 times faster than any existing one-dimensional lake model) The side effect is a divergence of the simulated near-bottom temperatures from the observed ones The inconsistencies in the bottom temperature are however comparable to those found in other lake models and can be reduced by fitting the model to a certain lake In this study we intentionally avoid any fitting using the model as a process-based mechanistic representation of heat transport in an ‘ideal lake’ capturing the general dynamics and mean behaviour observed in two real lakes Model simulations with FLake were forced using meteorological data (3-hourly resolution) from 1980–2010 from a weather station in Potsdam Some missing cloud cover data and other small data gaps were filled with data from nearby stations The model forcing variables include solar radiation humidity and long wave radiation estimated from cloud cover where t is the independent variable (time, day of the year) and a, b, c, d and e are free parameters. The extinction during the summer phytoplankton maximum was described by a Gauss (bell) function, g(t) (equation 5): Equations (4) were parameterized with the values in Table 1 in addition to σ = 35 Planktonic events may cause polymictic-dimictic regime shifts in temperate lakes Modeling the impact of global warming on water temperature and seasonal mixing regimes in small temperate lakes A change of climate provokes a change of paradigm: taking leave of two tacit assumptions about physical lake forcing Interannual variation in the thermal structure of clear and colored lakes Thermal structure of lakes varying in size and water clarity Significance of dissolved organic carbon in the prediction of thermocline depth in small Canadian shield lakes Effects of whole-lake base addition on thermal stratification in three acidic adirondack lakes water clarity and climatic variability on mixing depths in Canadian Shield lakes Effects of climate variability on transparency and thermal structure 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duration on plankton succession during spring in a shallow polymictic lake Warming promotes cold-adapted phytoplankton in temperate lakes and opens a loophole for Oscillatoriales in spring The North Atlantic Oscillation and plankton dynamics in two European lakes–two variations on a general theme Climate change uncouples trophic interactions in an aquatic ecosystem Plankton dynamics under different climatic conditions in space and time On conditions for the vernal blooming of phytoplankton Journal du Conseil International pour l’Exploration de la Mer Critical depth and critical turbulence: Two different mechanisms for the development of phytoplankton blooms moderately flushed lake to reduced external phosphorus and nitrogen loading turbid and back–long-term changes in macrophyte assemblages in a shallow lake Long-Term Study of the Heiligensee (1975–1992)–Evidence for Effects of Climatic-Change on the Dynamics of Eutrophied Lake Ecosystems Simulated long-term temperature and dissolved 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of multiannual thermal profiles in deep Lake Geneva: A comparison of one-dimensional lake models LakeMIP Kivu: evaluating the representation of a large deep tropical lake by a set of one-dimensional lake models Using the hydrodynamic model DYRESM based on results of a regional climate model to estimate water temperature changes at Lake Ammersee The classification of mixed-layer dynamics in lakes of small to medium size 10.1175/1520-0485(1980)010<1104:Tcomld>2.0.Co;2 (1980) Cyanobacteria dominance: Quantifying the effects of climate change Alternative explanations for rising dissolved organic carbon export from organic soils Dissolved organic carbon trends resulting from changes in atmospheric deposition chemistry Photo-electric measurements of submarine illumination throughout the year Analysis and modelling of the interactive effects of temperature and light on phytoplankton growth and relevance for the spring bloom Long-term changes in oxygen depletion in a small temperate lake: effects of climate change and eutrophication Response of hypolimnetic oxygen concentrations in deep Swiss perialpine lakes to interannual variations in winter climate Verhandlungen der Internationalen Vereinigung für Theoretische und Angewandte Limnologie 30 FLake-Global: Online lake model with worldwide coverage A parameterized model of heat storage by lake sediments Identifying cardinal dates in phytoplankton time series to enable the analysis of long-term trends Patterns and mechanisms of phytoplankton variability in Lake Washington (USA) R. Core Team (2015). R: A language and environment for statistical computing v. 3.1.3. R Foundation for Statistical Computing, Vienna, Austria. URL: http://www.R-project.org/ Download references We thank Patrick Neale for assistance with statistical analyses Ursula Newen and Helgard Täuscher for sampling and sample processing and the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) for the long-term ecological program Meteorological data were kindly provided by the German Weather Service Schmidt and Torsten Seltmann provided valuable input This research was funded by a German Science Foundation (DFG) grant (No was additionally supported by the DFG grant IceBound (KI-853/11-1) was supported by the DFG grant LakeRisk (AD 91/13-1) and the EU-project LIMNOTIP funded under the FP7 ERA-Net Scheme (Biodiversa Leibniz-Institute of Freshwater Ecology and Inland Fisheries Department of Ecohydrology Leibniz-Institute of Freshwater Ecology and Inland Fisheries Department of Ecosystem Research Freie Universität Berlin Department of Biology performed the modelling and statistical analyses and wrote the manuscript All authors contributed to interpreting the results and editing the manuscript The authors declare no competing financial interests Download citation Anyone you share the following link with will be able to read this content: a shareable link is not currently available for this article Nature Reviews Earth & Environment (2020) Sign up for the Nature Briefing newsletter — what matters in science this mixed-use building has large stepped terraces the concrete volume has two external staircases connecting the five levels of apartments The successive setbacks of the levels solve privacy problems Each floor opens up fully towards its terrace with silvery curtains shielding residents from being seen from outside The rear elevation shows the stack of levels creating a covered public plaza in front of the gallery space on the ground floor there arent any match using your search terms Wednesday till Friday 18.00-21.30Saturday and Sunday 12.00-14.00 + 18.00-21.30 AddressVilla KellermannMangerstraße 3414467 Potsdam.How to get there ...var cex1 = "aW5mb0B2aWxsYWtlbGxlcm1hbm4uZGU=";var dex1 = atob(cex1);dex1 = decodeURIComponent(escape(dex1));jQuery(document).ready(function() {jQuery(".ex1").html(""+dex1+"");});+49 331 200 465 40.villakellermann.de There’s a graceful connection between old and new at restaurant Villa Kellermann at Heiligen See in Potsdam three rooms designed in entirely different ways confidently flow together: The Elephant Room Flirting with one another from across the room they don’t exactly make it easy to choose one interior over the other The view of the new garden just opposite is a dream Truly everything at Villa Kellermann is harmoniously combined and realised to perfection. 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