Eawag’s Department of Aquatic Ecology is currently home for eight research groups that cover the broad disciplines of ecology and evolution from the individual to the community and ecosystem level, utilizing a wide range of tools and techniques from microscopes to molecular genetics. Read more
Until recently, researchers assumed that Switzerland had around 20 native species of amphipods. Now, a project by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and the University of Zurich has revealed that...
Until recently, researchers assumed that Switzerland had around 20 native species of amphipods. Now, a project by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and the University of Zurich has revealed that there are actually more than 40. It is always worth taking a closer look, because we can only protect the things that we know exist.
Environmental DNA allows upscaling spatial patterns of biodiversity in freshwater ecosystems
The alarming declines of freshwater biodiversity call for efficient biomonitoring at fine spatiotemporal scales, such that conservation measures be grounded upon accurate biodiversity data. Here, we show that combining environmental DNA (eDNA) extracted from stream water samples with models based on hydrological first principles allows upscaling biodiversity estimates for aquatic insects at very high spatial resolution. Our model decouples the diverse upstream contributions to the eDNA data, enabling the reconstruction of taxa distribution patterns. Across a 740-km2 basin, we obtain a space-filling biodiversity prediction at a grain size resolution of 1-km long stream sections. The model’s accuracy in matching direct observations of aquatic insects' local occurrence ranges between 57-100%. Our results demonstrate how eDNA can be used for high-resolution biodiversity assessments in rivers with minimal prior knowledge of the system. Our approach allows identification of biodiversity hotspots that could be otherwise overlooked, enabling implementation of focused conservation strategies.
How pulse disturbances shape size-abundance pyramids
Ecological pyramids represent the distribution of abundance and biomass of living organisms across body-sizes. Our understanding of their expected shape relies on the assumption of invariant steady-state conditions. However, most of the world’s ecosystems experience disturbances that keep them far from such a steady state. Here, using the allometric scaling between population growth rate and body-size, we predict the response of size-abundance pyramids within a trophic guild to any combination of disturbance frequency and intensity affecting all species in a similar way. We show that disturbances narrow the base of size-abundance pyramids, lower their height and decrease total community biomass in a nonlinear way. An experimental test using microbial communities demonstrates that the model captures well the effect of disturbances on empirical pyramids. Overall, we demonstrate both theoretically and experimentally how disturbances that are not size-selective can nonetheless have disproportionate impacts on large species.
On biological evolution and environmental solutions
Drawing insights from multiple disciplines is essential for finding integrative solutions that are required to tackle complex environmental problems. Human activities are causing unprecedented influence on global ecosystems, culminating in the loss of species and fundamental changes in the selective environments of organisms across the tree of life. Our collective understanding about biological evolution can help identify and mitigate many of the environmental problems in the Anthropocene. To this end, we propose a stronger integration of environmental sciences with evolutionary biology.
Population genetics approaches to investigate how the massive level of habitat fragmentation affects population connectivity of crayfish, and if technical countermeasures effectively mitigate the negative effects of fragmentation.
New tools to monitor changes in ecosystem conditions and to quantify genetic changes of populations in (semi-)natural environments to predict how human mediated environmental change will influence stability and resilience of ecosystems.
We test how natural selection acts on quantitative immune defence traits and how ecological factors create variation in the form and strength of selection.
Assess the distribution and genetic structure of all amphipod species in Switzerland.