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.
In our recently published study in Molecular Ecology, Emanuel A. Fronhofer, Florian Altermatt, and me analyzed empirically observed genetic diversity of Gammarus fossarum metapopulations across the Rhine drainage area within Switzerland. We used microsatellite data and stochastic simulations to study the role of dispersal behaviour on observed genetic diversity. Allelic richness and observed heterozygosity were higher in more central nodes, unlike expected heterozygosity. Stochastic simulations suggest upstream movement probability and dispersal rate to be key factors explaining this finding. The study is open access. A huge thank you to Anja Westram and Jukka Jokela for support early on during analysis and providing data.
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.
It is an ambassador for healthy and diverse streams. Where it occurs in large numbers, the stream is healthy. Being named animal of the year, Gammarus fossarum is also a tribute to the countless small, inconspicuous organisms that keep freshwater ecosystems functioning in the first place. More information about the animal of the year can be found on the Pro Natura webpage (in German).