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

19.03.​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.
Faust, E., Rigby, K., Olsson, A., Alenius, B., Moksnes, P. O., & Jahnke, M. (2025). Empowering regional conservation: genetic diversity assessments as a tool for eelgrass management. Molecular Ecology. doi:10.1111/mec.17656, Institutional Repository

To halt the loss of biodiversity, collaboration among scientists, managers and decision-makers is vital. Although biodiversity loss is a global problem, management actions influencing diversity are often on a local to regional scale. Our study is an example of a regional conservation genomic assessment developed in collaboration between scientists and managers. We used 2bRAD sequencing to assess 18 eelgrass (Zostera marina) meadows in northwestern Sweden, an area that has experienced large losses of eelgrass since the 1980s. Genetic diversity was comparable to other assessed meadows in the Atlantic, but an order of magnitude lower than eelgrass in the Pacific. All but one meadow showed high rates of sexual reproduction. Almost all meadows were divergent but grouped into five genetic clusters. Four of the clusters correspond to geographic regions that can be used to define management units. Meadows in areas with a high decline in eelgrass between the 1980s and 2020s are more inbred than meadows in areas with an increase in eelgrass. Overall, our results indicate that striving to protect a number of large eelgrass meadows within each genetic cluster is important for maintaining the genetic diversity and connectivity of eelgrass in northwestern Sweden and is likely beneficial for the wider ecosystem. We estimate current indicators and essential biodiversity variables and discuss their challenges in marine facultative clonal species. We showcase how regional-scale conservation genomic assessments can serve as a foundation for protection and restoration of a priority species.

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