On 19. - 24. 11. 2019 I was in business trip in IRSTEA, Aix en Provance, France. Together with Dr Arnaud Sentis and his colleagues we discuss current research project as well as we discuss new possibilities of co-operation in future.  In addition, I was ask have a lecture at this institute. Specifically, my lecture was entitled: Using stable isotopes to study aquatic food webs.