Eawag - Swiss Federal Institute of Aquatic Science and Technology

We study ecology, evolution and biodiversity of fishes and other aquatic organisms. We are interested in the mechanisms that drive the origins, the maintenance and the loss of species, genetic and functional diversity.

Out and about with the electric fishing boat: the fish are caught, briefly stunned, fitted with a transmitter, and then released back into the water.

October 24, 2025 –

In this report, SRF Regionaljournal Aargau Solothurn provides information about our project ‘Climate Change and Fish Movement Patterns’. This relatively new research project in the major rivers of Aargau is attracting widespread...

In this report, SRF Regionaljournal Aargau Solothurn provides information about our project ‘Climate Change and Fish Movement Patterns’. This relatively new research project in the major rivers of Aargau is attracting widespread public interest.

Pair of whitefish (C. lavaretus) spawning near the shore in Lac d'Aiguebelette (Photo: Alamy).

May 9, 2025 –

The diversity of whitefish species in Swiss lakes is unique and plays a central role in lake ecosystems. A comprehensive Eawag report now summarises the results of 150 years of research on these fish. They make it clear that the...

The diversity of whitefish species in Swiss lakes is unique and plays a central role in lake ecosystems. A comprehensive Eawag report now summarises the results of 150 years of research on these fish. They make it clear that the mechanisms and environmental conditions that have contributed to their development must be taken into account in order to preserve this species diversity. Last but not least, protecting whitefish diversity helps to preserve the natural yield potential of lakes as a source of food for humans.

Research team taking fish samples in the Langete river using the electrofishing method (Photo: Dario Josi).

February 11, 2025 –

The public can take part in a survey to decide on the names of two fish species discovered by Bárbara Calegari and her colleagues. In this interview, the biologist explains where they live and how to make the diversity of our...

The public can take part in a survey to decide on the names of two fish species discovered by Bárbara Calegari and her colleagues. In this interview, the biologist explains where they live and how to make the diversity of our waters visible.

Figure 1. in Dr. Alexus Roberts-Hugghis publication "A classic key innovation constrains oral jaw functional diversification in fishes"

January 27, 2025 –

Another paper from Alexus showing that the modified pharyngeal jaw, while undoubtedly a functional innovation, at the same time also restricts the diversification of the feeding system.

More News from the Department of Fish ecology and evolution

Eawag News

Postdoctoral position in Aquatic Ecology

Internship in Alpine Lake Ecology (100%)

31.01.2026,

9.15 am

Hotel ARTE Olten

FIBER Seminar 2026

"Laichzeit! – Monitoring, Besatz & Aufwertungen – Wo sollen wir ansetzen?"

08.09.2026,

9.00 am

Swiss Museum of Transport, Lucerne

Info Day 2026: Water & Energy Transition

Info Day 2026

26.10.2026,

9.00 am

Eawag Dübendorf

Angewandte Naturschutzgenetik für die Praxis

PEAK-Basiskurs B38/26

Ahi, E. P., Sturmbauer, C., Albertson, R. C., & Singh, P. (2026). Molecular basis of variations in facial soft tissues: insights from cichlid fishes. Developmental Biology, 529, 200-212. doi:10.1016/j.ydbio.2025.10.014, Institutional Repository

The human face serves as a crucial component of attractiveness and identity, playing a pivotal role in social interactions. Teleost fish models, particularly zebrafish, have offered valuable insights into the developmental and molecular mechanisms governing craniofacial skeletogenesis, owing to the molecular conservation in these processes. However, knowledge regarding the morphogenic processes shaping facial soft tissues remains surprisingly sparse. On the human side, most causal evidence comes from gene–phenotype associations in clinical genetics; however, these studies rarely provide cellular-resolution analyses of facial soft tissues, leaving tissue- and cell-type–specific mechanisms unresolved. The diverse family of Cichlidae constitute ∼10 % of teleost fish species and represent an exceptional opportunity for evolutionary biology research due to their extensive ecological diversity and rapid speciation rates. Cichlid fishes also exhibit remarkable craniofacial morphological diversity, making them excellent models for studying both craniofacial skeletal and soft tissue morphogenesis. Utilizing the wealth of natural mutants within cichlid populations, this short review pitches cichlid fish models as valuable tools for investigating the genetic regulators and interactions underlying facial soft tissue formation. At present, most cichlid studies rely on comparative transcriptomics between closely related species with and without pronounced traits; these data are associative, and the regulatory hierarchy and primary drivers remain to be established through functional tests (e.g., genome editing). By synthesising developmental and regulatory mechanisms that influence morphological variations in facial soft tissues in cichlids and other model organisms, we create a blueprint for future molecular genetic investigations into facial diversity. Accordingly, we highlight the need for (i) causative functional studies in cichlids and (ii) cellular-resolution analyses of human facial soft tissues to bridge correlative and mechanistic evidence across systems.

Mohan, A., Matthews, B., & Räsänen, K. (2026). Predation risk magnifies fungicide-driven suppression of keystone shredder feeding and behaviour, slowing freshwater leaf-litter degradation. Environmental Pollution, 390, 127490 (10 pp.). doi:10.1016/j.envpol.2025.127490, Institutional Repository

Chemical pollution is a growing global threat, and freshwater habitats, which harbor disproportionate biodiversity and provide key ecosystem services, now face overlapping chemical and biological stressors whose combined effects can accelerate biodiversity loss. Fungicides, heavily used in forestry and agriculture, often leach to freshwater environments, but their impacts remain understudied, especially sub-lethal impacts such as changes in prey behaviour or detritivore-mediated decomposition. We examined the interactive effects of a widely used triazole fungicide (Tebuconazole) and a common biotic stressor (dragonfly predators) on a keystone detritivore, the freshwater isopod Asellus aquaticus, using a 2x2 factorial microcosm experiment in the laboratory. We reared isopods in groups in a combination of two fungicide (0 vs 50 μg/L Tebuconazole) and two predator (presence or absence of a caged predator) treatments and assessed changes in performance (behavioural activity, food consumption) after 21 days, followed by a survival assay in presence of a free-ranging predator. We found that Tebuconazole alone reduced feeding by 89 % and predator cues by 44 % relative to benign (clean water-no predator present) conditions, while both stressors together reduced feeding by 91 %, indicating that chemical stress overrode effects of predators. Isopods reared in the absence of a caged predator reduced their behavioural activity by 35 % when exposed to predator cues, whereas fungicide-exposed conspecifics showed no behavioural change, indicating impaired threat detection. Prior experience with predators nearly doubled survival against a free-ranging predator (45 % for predator-naive isopods vs 80 % for isopods reared with a caged predator), but this advantage vanished in the fungicide treatments (62 % survival). Collectively, our results demonstrate that environmentally relevant pesticide concentrations can change prey behaviour, increase predation risk, and potentially destabilize trophic interactions that regulate nutrient cycling. These findings underscore the need for freshwater risk assessments that capture how multiple interacting stressors affect organisms and the ecosystem functions they support.