(Dept. 3) Plankton and Microbial Ecology
Research in the Department of Plankton and Microbial Ecology on the shores of Lake Stechlin centres on impacts of global environmental change on inland waters. Consequences on the biodiversity and functioning of plankton communities in lakes receive particular attention. This includes investigations into the dynamics, activities and interactions of bacteria, phytoplankton, zooplankton and fungi. Field experiments, especially in a large outdoor facility dubbed the LakeLab in Lake Stechlin, are a hallmark of research in the department. Other essential elements are the analysis of long-term data, laboratory experiments and the development of ecological models and new methods to analyse plankton communities. We use the knowledge gained in theses studies to devise concepts and methods that foster the protection and sustainable management of inland waters in the face of ongoing environmental change.
Limnology and Oceanography
Flexible habitat choice of pelagic bacteria increases system stability and energy flow through the microbial loop
The theoretical study evaluated the microbial dynamics of particle-associated vs free-living bacteria. Bacterial generalists have the ability to utilize both habitats and increase stability and energy transport through the 'microbial loop'. Adaptive response strategies of bacteria are important to assess the consequences of increasing particle loads, e.g., sediment and microplastics.
The authors studied effects of warming on spring plankton dynamics in outdoor mesocosms. Experimental warming speeded up phytoplankton growth dramatically, triggering a massive bloom of phosphorus deficient algae that drove its zooplankton grazers to extinction. It shows that warming can aggravate the food quality mismatch at the plant–herbivore interface and limit energy transfer up the food web.
Despite significant progress in quantifying greenhouse gas emissions from dry inland waters, little is known about methane (CH4). The authors determined CH4 emissions from dry sediments across continents and found that the CH4 contribution ranged from 10 to 21% of the equivalent CO2 emissions. Therefore, CH4 emissions from dry inland waters should be considered for the global carbon cycle.
Characterizing the “fungal shunt”: parasitic fungi on diatoms affect carbon flow and bacterial communities in aquatic microbial food webs
The study demonstrates that parasitic fungi profoundly modify microbial interactions through several mechanisms (e.g., stimulating bacterial colonization on phytoplankton cells, altering the community composition of bacteria). Hence, fungal microparasites can substantially shape the microbially mediated carbon flow at the base of aquatic food webs which we termed "fungal shunt" .
The authors analyzed a combined total of 45,148 dissolved oxygen and temperature profiles and calculate trends for 393 temperate lakes that span 1941 to 2017. They found that a decline in dissolved oxygen is widespread in surface and deep-water habitats. Declines in dissolved oxygen in freshwater are 2.75 to 9.3 times greater than observed in the world’s ocean.