Mittwoch 17. Juni 2026 um 14.00 Uhr
Alexandra A.-T. Weber, Dr.
Eawag, Swiss Federal Institute of Aquatic Science and Technology
Title: A deep dive into quagga mussel invasion and depth-associated ecomorph differentiation
Abstract:
Quagga mussels are among the most successful freshwater invaders, with major ecological and economic impacts. By colonizing deep lake habitats, they act as ecosystem engineers, altering food webs and nutrient cycling, while also creating substantial management costs for drinking-water infrastructure, thermal water use, and fisheries. After invading North America in the early 1990s, quagga mussels have more recently expanded across Western Europe, including rapid ongoing spread in Switzerland and Austria. In this talk, I will present ongoing research on quagga mussel invasion history and depth-associated ecomorph differentiation. I will first summarize recent genomic results on global and local invasion routes, including evidence for multiple quagga mussel lineages in Europe. I will then focus on a striking phenomenon observed in quagga mussels: the emergence of shallow and deep ecomorphs along a depth gradient, despite little genetic differentiation. Using field sampling and laboratory experiments, we combine genomic, epigenomic, transcriptomic, and phenotypic data to investigate the molecular basis of this divergence. Preliminary results suggest that shallow and deep ecomorphs largely reflect developmental phenotypic plasticity rather than fixed genetic differences. They also suggest that the shallow ecomorph may be more generalist with broad environmental tolerance, whereas the deep ecomorph appears more specialized with a narrower tolerance range. These findings are important because the deep ecomorph likely contributes to the exceptional success of quagga mussels in deep lakes, where they can outcompete zebra mussels and strongly reshape invaded ecosystems. More broadly, this work asks how invasive species generate ecological specialization, expand into novel habitats, and transform ecosystems over short timescales.