Optical properties of ice in a shallow Chinese lake (Hanzhang) with consequent impacts on primary production.

Primary production is a key factor in assessing aquatic ecosystems and the global carbon cycle. Despite the ice-cover period lasting several months in many lakes, less attention has been paid to primary production in winter under ice compared to the open water period. In particular, the relationship between light conditions under ice and associated primary production remain not fully understood.

Strong Subseasonal Variability of Oxic Methane Production Challenges Methane Budgeting in Freshwater Lakes.

Methane (CH) accumulation in the well-oxygenated lake epilimnion enhances the diffusive atmospheric CH emission. Both lateral transport and in situ oxic methane production (OMP) have been suggested as potential sources. While the latter has been recently supported by increasing evidence, quantifying the exact contribution of OMP to atmospheric emissions remains challenging.

Variation of bacterial communities along the vertical gradient in Lake Issyk Kul, Kyrgyzstan.

We explored the diversity and community composition of bacteria along a vertical gradient in Lake Issyk Kul, Kyrgyzstan, one of the world's largest and deepest brackish lakes. We identified 4904 bacterial amplicon sequence variants based on the 16S rRNA gene analysis and determined significant changes in the composition, responding mainly to depth and salinity. A higher abundance of Proteobacteria and Bacteroidetes was observed in the surface waters and lake tributaries.

High Spatiotemporal Dynamics of Methane Production and Emission in Oxic Surface Water.

The discovery of methane (CH) accumulation in oxic marine and limnic waters has redefined the role of aquatic environments in the regional CH cycle. Although CH accumulation in oxic surface waters became apparent in recent years, the sources are still subject to controversial discussions. We present high-resolution in situ measurements of CH concentration and its stable isotope composition in a stratified mesotrophic lake.

Contribution of oxic methane production to surface methane emission in lakes and its global importance.

Recent discovery of oxic methane production in sea and lake waters, as well as wetlands, demands re-thinking of the global methane cycle and re-assessment of the contribution of oxic waters to atmospheric methane emission. Here we analysed system-wide sources and sinks of surface-water methane in a temperate lake. Using a mass balance analysis, we show that internal methane production in well-oxygenated surface water is an important source for surface-water methane during the stratified period.

Citizen science shows systematic changes in the temperature difference between air and inland waters with global warming.

Citizen science projects have a long history in ecological studies. The research usefulness of such projects is dependent on applying simple and standardized methods. Here, we conducted a citizen science project that involved more than 3500 Swedish high school students to examine the temperature difference between surface water and the overlying air (T-T) as a proxy for sensible heat flux (Q).

Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm.

Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening.

Planktonic events may cause polymictic-dimictic regime shifts in temperate lakes.

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.

Estimating In Situ Zooplankton Non-Predation Mortality in an Oligo-Mesotrophic Lake from Sediment Trap Data: Caveats and Reality Check.

Background: Mortality is a main driver in zooplankton population biology but it is poorly constrained in models that describe zooplankton population dynamics, food web interactions and nutrient dynamics. Mortality due to non-predation factors is often ignored even though anecdotal evidence of non-predation mass mortality of zooplankton has been reported repeatedly. One way to estimate non-predation mortality rate is to measure the removal rate of carcasses, for which sinking is the primary removal mechanism especially in quiescent shallow water bodies.

Enhancing surface methane fluxes from an oligotrophic lake: exploring the microbubble hypothesis.

Exchange of the greenhouse gases carbon dioxide (CO2) and methane (CH4) across inland water surfaces is an important component of the terrestrial carbon (C) balance. We investigated the fluxes of these two gases across the surface of oligotrophic Lake Stechlin using a floating chamber approach. The normalized gas transfer rate for CH4 (k600,CH4) was on average 2.

Seeking a compromise between pharmaceutical pollution and phosphorus load: Management strategies for Lake Tegel, Berlin.

Lake Tegel (Berlin, Germany) is controlled by two main inflows: inflow #1 (River Havel) is heavily phosphorus-laden, whereas inflow #2 is an artificial confluence that includes discharge from a municipal wastewater treatment plant distinguished by high levels of phosphorus and pharmaceuticals. To reduce the phosphorus load on the lake, a phosphorus elimination plant (PEP) is situated at inflow #2. Moreover, the two inflows are short-circuited by a pipeline that transfers part of the inflow #1 water to the PEP and finally releases it into inflow #2.

Plasticity in habitat use determines metabolic response of fish to global warming in stratified lakes.

We used a coupled lake physics and bioenergetics-based foraging model to evaluate how the plasticity in habitat use modifies the seasonal metabolic response of two sympatric cold-water fishes (vendace and Fontane cisco, Coregonus spp.) under a global warming scenario for the year 2100. In different simulations, the vertically migrating species performed either a plastic strategy (behavioral thermoregulation) by shifting their population depth at night to maintain the temperatures occupied at current in-situ observations, or a fixed strategy (no thermoregulation) by keeping their occupied depths at night but facing modified temperatures.