Wrack line formation and composition on shores of a large Alpine lake: The role of littoral topography and wave exposure.

Wrack lines are a key formation along shorelines that provide organic matter and bring ecological diversity to the local environment. Although wrack line formation has been extensively studied along marine beaches and estuaries, in contrast, knowledge about the environmental variables that promote wrack line formation within inland lakes is widely lacking. In one of the first studies to focus on wrack line formation on lakesides, we analysed the dimensions, volume, elevation and particulate composition of 36 wrack lines across 20 shore sections of a large, oligotrophic Alpine lake with natural water level fluctuations (Lake Constance-Obersee).

On the calculation of lake metabolic rates: Diel O and O technique.

Metabolic transformations have a major impact on the development of primary producers in aquatic systems and thus affect the dynamics of the entire aquatic food web. Furthermore, metabolic transformations contribute to the carbon budget and thereby influence CO emissions from aquatic systems. Several techniques have been developed that aim at an easy assessment of metabolic rates over long time periods or in many systems.

Sediment fluxes rather than oxic methanogenesis explain diffusive CH emissions from lakes and reservoirs.

Methane emissions from lakes and reservoirs are a major natural source in the global budget of atmospheric CH. A large fraction of these emissions are due to diffusive transport of CH from surface waters to the atmosphere. It was suggested recently that CH production in the oxic surface waters is required to compensate for diffusive CH emissions from lakes.

Lake Metabolism: Comparison of Lake Metabolic Rates Estimated from a Diel CO2- and the Common Diel O2-Technique.

Lake metabolism is a key factor for the understanding of turnover of energy and of organic and inorganic matter in lake ecosystems. Long-term time series on metabolic rates are commonly estimated from diel changes in dissolved oxygen. Here we present long-term data on metabolic rates based on diel changes in total dissolved inorganic carbon (DIC) utilizing an open-water diel CO2-technique.

Export of Dissolved Methane and Carbon Dioxide with Effluents from Municipal Wastewater Treatment Plants.

Inland waters play an important role for regional and global scale carbon cycling and are significant sources of the atmospheric greenhouse gases methane (CH4) and carbon dioxide (CO2). Although most studies considered the input of terrestrially derived organic and inorganic carbon as the main sources for these emissions, anthropogenic sources have rarely been investigated. Municipal wastewater treatment plants (WWTPs) could be additional sources of carbon by discharging the treated wastewater into the surrounding aquatic ecosystems.

The consequences of internal waves for phytoplankton focusing on the distribution and production of Planktothrix rubescens.

Consequences of internal wave motion for phytoplankton and in particular for the distribution and production of the harmful and buoyant cyanobacterium Planktothrix rubescens were investigated based on data from two field campaigns conducted in Lake Ammer during summer 2009 and 2011. In both years, P. rubescens dominated the phytoplankton community and formed a deep chlorophyll maximum (DCM) in the metalimnion.

Importance of the autumn overturn and anoxic conditions in the hypolimnion for the annual methane emissions from a temperate lake.

Changes in the budget of dissolved methane measured in a small temperate lake over 1 year indicate that anoxic conditions in the hypolimnion and the autumn overturn period represent key factors for the overall annual methane emissions from lakes. During periods of stable stratification, large amounts of methane accumulate in anoxic deep waters. Approximately 46% of the stored methane was emitted during the autumn overturn, contributing ∼80% of the annual diffusive methane emissions to the atmosphere.

In-situ optical and acoustical measurements of the buoyant cyanobacterium p. Rubescens: spatial and temporal distribution patterns.

Optical (fluorescence) and acoustic in-situ techniques were tested in their ability to measure the spatial and temporal distribution of plankton in freshwater ecosystems with special emphasis on the harmful and buoyant cyanobacterium P. rubescens. Fluorescence was measured with the multi-spectral FluoroProbe (Moldaenke FluoroProbe, MFP) and a Seapoint Chlorophyll Fluorometer (SCF).