TBG-Project Kathrin Theissinger

Functional Environmental Genomics

Freshwater Crayfish and Their Invasive Disease in Europe

European Noble Crayfish (Astacus astacus) ​Foto: © Kathrin Theissinger

Institution: Senckenberg Gesellschaft für Naturforschung

SUMMARY

Biological invasions are the second largest contributor to the loss of biodiversity. 

The conservation of freshwater biodiversity has, in the past, received less attention than the terrestrial biodiversity. However, current estimated extinction rates of freshwater species exceed those of terrestrial species. Freshwater crayfish are keystone species in European freshwater ecosystems. As ecosystem engineers, they have a high impact on freshwater ecosystem biodiversity. Additionally, they have a high economic value as human food delicacy. Unfortunately, population trends of native crayfish all across Europe are in severe decline. The main threats they are exposed to are the increasing populations of invasive North American crayfish, which are vectors of the crayfish plague pathogen Aphanomyces astaci, an oomycete listed amongst the 100 worst invasive species worldwide. North American crayfish species are usually resistant towards the crayfish plague disease. 

For European crayfish, however, A. astaci is a highly infectious pathogen, leading to crayfish mortality usually within a few days to weeks, depending on pathogen strain virulence and environmental conditions. However, recent reports from studies conducted both in the laboratory and in the wild indicate that A. astaci-exposed noble crayfish can, in some cases, resist acute crayfish plague infection. In my research we use a multi-scale approach, from molecular to trophic and evolutionary levels, to address the consequences of host-parasite interactions on European freshwater biodiversity and ecosystems. 

We investigate the molecular mechanisms underlying crayfish plague immune resistance within an original transcriptomic framework. Furthermore, we test hypotheses on host-jumps and the host-parasite co-evolution by culturing various A. astaci strains from different host species and conducting controlled laboratory cross-infection experiments. With the A. astaci pure cultures we do whole genome sequencing and subsequent GWAS analyses from more and less virulent strains to infer whether the virulence is genetically encoded. We also study the impact of A. astaci interactions with zooplankton in freshwater food webs by conducting grazing experiments with Daphnia species. 

This research will contribute to understand the impacts of A. astaci on European freshwater ecosystems, by investigating its effects from molecular to species to ecosystem levels, and will aid conservation and management of European freshwater crayfish to prevent them from extinction.

Project members

Contributors

Odile Lecompte, University of Strasbourg
Anne Thielsch, University of Koblenz-Landau

GROUP EXPERTISE / METHODS

  • whole genome and transcriptome de novo assembly and annotation
  • RNAseq and gene expression analyses
  • comparative genomics
  •  population genetics and genomics

GENOMES SEQUENCED

Noble crayfish Astacus astacus
(assembly in preparation)