Selected publications

The authors investigated how ongoning changes in winter conditions may have consequences for annual phytoplankton biomass and production. They showed that earlier winter/spring runoff and snowmelt during warmer winters lead to lower summer chlorophyll-a in 41 north temperate lakes in Europe and North America.

Diversity and community composition of bacteria along vertical gradients were studied in Lake Issyk Kul, Kyrgyzstan, the 6th deepest lake worldwide and the largest high-altitude lake. In the molecular assessment, the 16S rRNA gene analysis revealed significant changes in the composition, responding mainly to depth and salinity with Planctomycetes and Chloroflexi dominating in the deepest layers.

This study is an important step to establish the use of satellite imagery for inland water quality monitoring. By using in situ measurements of the algal pigment chlorophyll-a from small-sized lowland lakes in Northern Germany, we identified the best performing atmospheric correction and bio-optical algorithm to accurately estimate chlorophyll-a from Sentinel 2 satellite images. 

Climate change causes a decrease in the ice cover on lakes throughout the world. Yet, there has been insufficient research into how this decline of the winter period affects the interplay of phytoplankton and zooplankton. This study shows that even a gradual decline in the average duration of ice cover can result in abrupt changes in plankton dynamics.

The vertical flux of marine snow reduces atmospheric CO2. In particular, particle associated prokaryotes are responsible for organic C-loss. Analysis of prokaryotic heterotrophic production a. species richness in the North Atlantic reveal that C- loss a. associated microbial richness are different with particle fractions. Especially large, fast-sinking particles drive C-flux a. -sequestration.

This study investigated whether the microbial degradation of more refractory organic matter (OM) is stimulated by the addition of well available OM from dead zooplankton. A significantly higher respiration was measured when zooplankton-derived OM was added to ratio of 1:1. Stimulation was stronger in a complex microbial community with eukaryotes than just bacteria. 

Phaeocystis pouchetii regularly dominates Arctic marine plankton and is considered a key food source supporting highly productive fisheries. But the relevance of biomass transfer to higher trophic levels is debated. This study shows that endometabolic markers can be correlated to the metabolic state of Phaeocystis populations, which allows testing the influence on zooplankton trophic transfer.

The authors have shown that shifts in microbial communities triggered by chronic exposure to low concentrations of silver nanoparticles increases the community tolerance to silver, as described in the pollution-induced community tolerance (PICT) concept, with consequences for leaf litter decomposition, a pivotal process in forest streams.