Anoxic aquatic systems - IM
The research area Anoxic Aquatic Systems (formerly known as Microbial Hydrobiology) is dedicated to the study of microorganisms in anoxic aquatic ecosystems. At our institute, research focuses on the analysis of phototrophic microbial communities, especially anoxic ones, that develop in the water column of Lake Cadagno, a unique meromictic lake located in the Swiss Alps and an international reference point for the study of stratified aquatic systems.
Cadagno is an exceptional natural laboratory: in the chemocline region, where oxygenated surface waters meet deep anoxic waters rich in sulfides, a complex community of anoxigenic phototrophic sulfur bacteria thrives. These microorganisms form a characteristic pink layer visible in the water column and play a key role in major biogeochemical cycles.
Thanks to continuous monitoring that has been ongoing for over forty years, Lake Cadagno has made it possible to characterize the composition and ecological dynamics of these microbial communities, highlighting seasonal and inter-annual variations. This long-term work has led to the discovery of surprising phenomena, such as the bioconvection generated by Chromatium okenii, a collective behavior unique among anoxic phototrophic bacteria.
The study of the anoxic aquatic systems of Lake Cadagno not only deepens our understanding of microbial interactions in stratified aquatic environments, but also provides essential models for interpreting extreme ecological conditions and processes typical of the planet's primordial ecosystems.
Cadagno is an exceptional natural laboratory: in the chemocline region, where oxygenated surface waters meet deep anoxic waters rich in sulfides, a complex community of anoxigenic phototrophic sulfur bacteria thrives. These microorganisms form a characteristic pink layer visible in the water column and play a key role in major biogeochemical cycles.
Thanks to continuous monitoring that has been ongoing for over forty years, Lake Cadagno has made it possible to characterize the composition and ecological dynamics of these microbial communities, highlighting seasonal and inter-annual variations. This long-term work has led to the discovery of surprising phenomena, such as the bioconvection generated by Chromatium okenii, a collective behavior unique among anoxic phototrophic bacteria.
The study of the anoxic aquatic systems of Lake Cadagno not only deepens our understanding of microbial interactions in stratified aquatic environments, but also provides essential models for interpreting extreme ecological conditions and processes typical of the planet's primordial ecosystems.
Il gruppo di Idrobiologia microbica presso del settore Ecologia microbica si occupa principalmente dei seguenti compiti:
- Il monitoraggio inter- e intra-stagionale del lago meromittico di Cadagno.
- Lo studio eco-fisiologico dei batteri anaerobici "phototrophic sulfur bacteria" del chemoclinio.
- Fornisce assistenza scientifica e didattica alla fondazione Centro Biologia Alpina (CBA) di Piora.
We are mainly concerned with monitoring and characterizing the ecological dynamics of the community of ancestral anoxygenic phototrophic sulfur bacteria that form a characteristic pink water in the chemocline region. We also study their physiology with classical and molecular microbiology experiments both in the laboratory and in their natural environment. In synergy with the Center for Alpine Biology (CBA) foundation in Piora, we coordinate scientific, outreach and educational activities inherent to microbial ecology topics.
Over the past 40 years, improved microbial identification techniques have been developed and applied in order to monitor the evolution and dynamics of the different layers of the water column more accurately, with particular interest in the pink chemocline bacterial layer. The dynamics of the different species of "purple" (PSB) and "green" (GSB) "sulfur bacteria" are also studied at an intra-seasonal level in order to highlight the different evolutionary strategies.
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In the chemocline of Lake Cadagno irradiation of light, inverse gradients of oxygen and sulfide favor the development of a unique community of primordial anoxygenic sulfur phototrophic bacteria. Each individual bacterial population living in this ecological niche is subjected to physical, chemical and biological stressors that have led to different evolutionary pathways with correspondingly different physiological adaptations. For example, during anoxygenic photosynthesis, "Purple sulfur bacteria (PSB)" can oxidize sulfide (H2S) into elemental sulfur (S0) and store it in their cells as reserve globules, which "Green sulfur bacteria (GSB)" do not. Or again, the ability of active movement by the PSB Chromatium okenii favors a phenomenon observed only in Lake Cadagno, called bioconvection. The synchronized movement of millions of Chromatium okenii induces the mixing of portions of water even larger than one meter, resulting in the exclusion of other PSB species and GSBs from the ecologically most advantageous zone.
Due in particular to the photosynthetic activity of the pink bacterial layer, the Cadagno can support the presence of many more fish than an ordinary alpine lake, making it popular with fishermen as well.
Due in particular to the photosynthetic activity of the pink bacterial layer, the Cadagno can support the presence of many more fish than an ordinary alpine lake, making it popular with fishermen as well.
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The synergy with the Alpine Biology Centre (CBA) foundation in Piora makes it possible to equip their buildings with the necessary instruments for advanced scientific research in microbial ecology, promoting an international scientific research pole. In addition, this allows a high level of academic quality with the regular presence of leading Swiss universities, as well as some international ones. The scientific and educational excellence fosters a natural dissemination of science offered in different forms to the numerous visitors to the region.
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We regularly offer opportunities for bachelor and master's students to undertake thesis projects related to the microbial ecology of the meromictic lake Cadagno.
The increasingly complex scientific knowledge produced in past few years rarely succeeds in being passed on to the population, actually distancing scientific knowledge from society. The importance of the results of scientific research in the unique ecosystem of the meromictic Lake Cadagno is intended to be shared by promoting various dissemination activities in close collaboration with the Centro di Biologia Alpina (CBA) foundation. Find out more about Design for Science .