Prevalence of the crayfish plague pathogen in red swamp crayfish populations in western France: How serious is the risk for the native white-clawed crayfish?

The crayfish plague pathogen Aphanomyces astaci has been implicated in a number of mass mortalities and irreversible population declines of native crayfish across Europe. At present, the reservoirs of the pathogen in Europe are mainly populations of invasive North American crayfish species. In southwestern Europe, including France, a particularly widespread invader is the red swamp crayfish Procambarus clarkii.

Diversity and distribution of Aphanomyces astaci in a European hotspot of ornamental crayfish introductions.

Ornamental trade has become an important introduction pathway of non-native aquatic species worldwide. Correspondingly, there has been an alarming increase in the number of established crayfish of aquarium origin in Europe over the previous decade. The oomycete Aphanomyces astaci, the pathogen causing crayfish plague responsible for serious declines of European crayfish populations, is dispersed with introduced North American crayfish.

Spatial insurance against a heatwave differs between trophic levels in experimental aquatic communities.

Climate change-related heatwaves are major threats to biodiversity and ecosystem functioning. However, our current understanding of the mechanisms governing community resistance to and recovery from extreme temperature events is still rudimentary. The spatial insurance hypothesis postulates that diverse regional species pools can buffer ecosystem functioning against local disturbances through the immigration of better-adapted taxa.

Expanding ecological assessment by integrating microorganisms into routine freshwater biomonitoring.

Bioindication has become an indispensable part of water quality monitoring in most countries of the world, with the presence and abundance of bioindicator taxa, mostly multicellular eukaryotes, used for biotic indices. In contrast, microbes (bacteria, archaea and protists) are seldom used as bioindicators in routine assessments, although they have been recognized for their importance in environmental processes. Recently, the use of molecular methods has revealed unexpected diversity within known functional groups and novel metabolic pathways that are particularly important in energy and nutrient cycling.