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Climate change is predicted to increase sea level, causing salt water intrusion in current freshwater environments. This increase in salinity facilitates brackish communities to establish. In the Baltisch-Deutsches Hochschulkontor financed project "The influence of sea level rise on the microbiota of the model organism Theodoxus fluviatilis" scientists from the University of Greifswald and from the Estonian University of Life Sciences (EMÜ) investigated the influence of increasing salinity on the gut microbiota in the model organism Theodoxus fluviatilis also known as River nerite.

The project was led by Prof. Daniel Herlemann, who heads the group of Microbial Ecophysiology at the Estonian University of Life Science and Prof. Jan Peter Hildebrandt, head of the Department Animal Physiology and Biochemistry at the University of Greifswald. The collaboration of an animal physiologist and a microbiologist proved to be very successful to combine physiological responses of the invertebrate host with the bacterial community adaptation during salt stress.

The study revealed that the microbiome of brackish snails were relatively resistance against changes in salinity. In contrast responded microbiomes of snails sampled at freshwater highly sensitive. "This indicates that salt water intrusions to freshwater areas have a strong effect on the host-microbe interaction in Theodoxus fluviatilis, despite the abundant presence of the snail in brackish water" said Prof. Herlemann from EMÜ. The microbiome has important functions for nutrient acquisition and detoxifying compounds in snails and therefore loss of key bacteria can interrupt the host-microbiome symbiosis.

The concept of "freshwater vulnerability" resulting from this project will be implemented in Herlemanns' ongoing Mobilitas Pluss Top Researcher project "RADIX" where intensive investigations on the effect of salt on the microbiome of invertebrate model organisms are performed.