Hints on how to keep Gammarus fossarum

Flow through system at Eawag, used to keep Gammarus fossarum.

Being a field biologist by training, I always wanted to study my beloved amphipods under laboratory conditions. Turns out it is not as straightforward. Our recent publication in Science of The Total Environment highlights some of the things we learned over the last few years. While some amphipod species such as Hyalella azteca are easy to breed in captivity, the freshwater genus Gammarus from Central Europe is notoriously hard to keep and maintain in the lab. Hence, most experiments rely on wild-caught animals. From an scientific point of view, having lab-bred individuals available is the preferred option. To improve survival and reproduction in lab cultures of Gammarus fossarum, we caught thousands of G. fossarum and ran several experiments in our laboratory facilities, tweaking around with food supply, day-length, water temperature, cage size etc. We supplemented the diet of G. fossarum with protein-rich food and provided additional shelter. Both these measures increased survival rate of laboratory-based populations significantly, especially the feed enrichment. We also manipulated the day length (fixed vs. variable). We did not observe a significant effect of day length on the abundance and reproductive activity of G. fossarum. Apart from these main findings, we provide several detailed husbandry protocols in the paper (https://doi.org/10.1016/j.scitotenv.2022.158730). They are intended as starting point for future experiments in environmental sciences and ecotoxicology that rely on lab-bred G. fossarum. I want to thank everyone involved in improving our lab cultures of G. fossarum, especially Sarah Bollina, Eva Cereghetti, Morris Galli, Samuel Hürlemann, Silvana Kaeser, Chelsea Little, Manja Schleich and I want to acknowledge financial support by Eawag, University of Zurich, and BAFU.

New groundwater amphipod discovered

Niphargus arolaensis, a newly described groundwater amphipod from Switzerland

Thanks to the collaboration with many water well managers, Nicole Bongni was able to describe a previously undocumented biological diversity in groundwater in her master’s thesis. The focus was on amphipods, in particular the genus Niphargus. Among the discoveries was a completely new species, which we have now described scientifically in Subterranean Biology. The name of the new species: Niphargus arolaensis, the Aare groundwater amphipod. The name is derived from the fact that we have only been able to detect the species at three sites in the Aare River basin. This research shows that we still understand the groundwater habitat far too poorly and therefore cannot protect it adequately. Thanks to the project AmphiWell we can continue basic research on this topic.

Biodiversity increases and decreases ecosystem stability

Experiments have shown that biodiversity may increase or decrease ecosystem stability. As part of a collaboration between Owen Petchey’s lab at University of Zurich and Florian Altermatt’s lab at Eawag, we performed a large experiment that showed that species richness can simultaneously increase and decrease ecological stability. This highlighed that one should consider multiple stability components and that this could provide new insights. The study was recently published in Nature (read article here) and I am proud to be part of this fruitful project. The story behind the paper can be read in this blog post by Frank Pennekamp.

An endemic amphipod of the Alps

Gammarus alpinus from Lej da Silvaplauna (Switzerland)

In our most recent paper, Florian Altermatt, Cene Fišer, and me describe a new  amphipod species that is endemic to the Alps. What has been considered to belong to the circumboreal Gammarus lacustris species complex turned out to be a highly diverged lineage. It represents an own species within the Alps. Given its natural but restricted distribution, we name the endemic amphipod species Gammarus alpinus sp. nov.

Already endangered?

The species is commonly found in high alpine lakes of Central Europe. Although its wide distribution, invasive species and increasing anthropogenic pressure in its natural habitat impose challenges to the newly described species. Assigning a name to this biological entity hopefully facilitates the conservation efforts. Our study is published in the Zoological Journal of the Linnean Society. It highlights the importance of combining different methods to resolve cryptic diversity. Furthermore I would hereby like to acknowledge all the people and institutions that helped to conduct this study.

Alpine chironomids of Switzerland


Our study on chironomids of high elevation and non-glacial streams is available online via Schweizerbart. We found highly diverse and spatially-structured communities of these ecologically important macroinvertebrates. Rarity was prevalent and highlighted the local differences between sites. Regional patterns reflected distributions of the more common taxa. Hence, projections of chironomid assemblages under climate warming are difficult and conservation of these diverse habitats is therefore important.