Department Fish Ecology and Evolution

Fish Ecology & Evolution (FishEc)

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.

 

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News

Two new fish species discovered in Swiss waters

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.
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Evolution Letters publication from Dr. Alexus Roberts-Hugghis

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.

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.
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Biodiversity increases organic nutrient availability across ecosystems

Gebänderte Prachtlibelle, Männchen (lat. Calopteryx splendens, engl. Banded demoiselle) mit ihrer Beute (Foto: Maja Ilić).
October 17, 2024 –

Insects and spiders are superfoods: rich in essential fatty acids and therefore an important food supply for birds, fish, reptiles, amphibians and small mammals.

Insects and spiders are superfoods: rich in essential fatty acids and therefore an important food supply for birds, fish, reptiles, amphibians and small mammals.
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Fisheries advisory service: new location in French-speaking Switzerland

The fisheries advisory service (FIBER) puts research findings relevant to fisheries into practice (Photo: Adobe Stock).
October 11, 2024 –

The Swiss fisheries advisory office (FIBER) promotes sustainable fisheries through advice and training. It now has a location in French-speaking Switzerland.

The Swiss fisheries advisory office (FIBER) promotes sustainable fisheries through advice and training. It now has a location in French-speaking Switzerland.
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More News from the Department of Fish ecology and evolution

Eawag News

Seminars

26.03.​2025,
02.04.​2025,
2.00 pm
Eawag Kastanienbaum, Seeheim
Megafauna and the maintenance of biodiversity
16.04.​2025,

Latest Publications

Cereghetti, E., Bossart, R., Bruder, A., Krähenbühl, A., Wolf, F., & Altermatt, F. (2025). The year of a leaf: tracking the fate of leaf litter and its nutrients during aquatic decomposition and consumption. Ecology, 106(1), e4520 (8 pp.). doi:10.1002/ecy.4520, Institutional Repository

Temperate streams are subsidized by inputs of leaf litter peaking in fall. Yet, stream communities decompose dead leaves and integrate their energy into the aquatic food web throughout the whole year. Most studies investigating stream decomposition largely overlook long-term trajectories, which must be understood for an appropriate temporal upscaling of ecosystem processes. Using mesocosms, we quantified changes in carbon, nitrogen, and phosphorus content of three leaf species during decomposition at weekly to multi-month intervals for up to a year; then, we tested how decomposition duration affected the subsequent consumption by a keystone amphipod macroinvertebrate. Over a year, nitrogen and phosphorus percentage increased across all leaf species, but only the recalcitrant species maintained initial levels of absolute nitrogen and phosphorus. Prolonged decomposition barely affected or impaired amphipod consumption of labile leaf species, whereas it enhanced feeding on the recalcitrant species. Overall, we demonstrate that recalcitrant leaves might serve as longer stored potential resources for when labile species have already been consumed and that their increasing palatability observed over multi-month intervals of sustained decomposition may stabilize fluctuations in the rates of leaf litter integration into aquatic food webs. This yearlong perspective highlights the relevancy of slow-decomposing leaves for aquatic detrital communities.
Davidsen, J. G., Eldøy, S. H., Piper, A. T., Moccetti, C., Brodersen, J., Whoriskey, F., & Power, M. (2025). Marine migration, thermal habitat use and feeding habits of Arctic charr (Salvelinus alpinus) in SW Greenland. Canadian Journal of Fisheries and Aquatic Sciences, 82, 1-14. doi:10.1139/cjfas-2024-0053, Institutional Repository

Climate change is altering northern coastal aquatic habitats, especially in fjords. Data on current ecosystem structure and biodiversity in many northern fjord and coastal ecosystems, especially for Greenland, are lacking. We used acoustic telemetry combined with stable isotope analyses in a southwest Greenland fjord to investigate marine migrations, marine, and freshwater thermal habitat use, and the marine feeding habits of 80 acoustically tagged Arctic charr over one year. During summer, most Arctic charr occupied the inner fjord. Models of Arctic charr thermal habitat use suggested higher experienced water temperatures in the inner compared to outer fjord (estimated 1.59◦ C difference) during tagged charr mean 70-day (SD = 14 days) residencies. During February and March, non-migratory individuals used warmer waters (+0.56◦ C higher) than fish that ultimately migrated to sea, suggesting that over-wintering habitat use patterns influenced migration tactics. Stable isotope mixing model analysis indicated that Arctic charr fed mainly on capelin, marine gammarids, and three-spine sticklebacks. The results provide a contemporary baseline for assessing predictions of potential changes in the ecology of Arctic charr in SW Greenland fjords.

Research Projects

How will climate change alter the phenology, biomass, and nutritional quality of cross-ecosystem fluxes?

Nutritional phenology with climate change
Coral adaptation to the future climates

simulating response of red sea coral species to rising temperatures
Tropical Reef. Credit Conor Waldock
Simulating the roles of dispersal, thermal tolerance, and adaptive potential in tropical reef fish responses to climate change

simulating tropical fish biodiversity
In this large-scale study we investigate the effects of climate change on fish movement patterns in the Swiss Rhine-Aare River network

Climate change and fish movement patterns

More research projects