COD LARVAL SURVIVAL · Elucidating the role of microbial communities in cod larval death and survival

This proposal contributes to solve a significant problem in commercial aquaculture: namely the high mortality of fish larvae caused by microbial infection. To enhance the survival of cod larvae I will gain in-depth insight into the microbiome of the cod larvae gastrointestinal tract by using novel and advanced correlative three-dimensional cryogenic-transmission electron microscopy and fluorescence in situ hybridization, and large-volume high-resolution focused ion beam scanning electron microscopy imaging approaches that were developed at the University of California, Berkeley and the Lawrence Berkeley National Laboratory in the U.S. I will adapt and apply these state-of-the-art imaging techniques to a research effort at the Norwegian University of Science and Technology (NTNU) designed to replace trial-and-error management of bacteria in larval cod production with an evidence-based gnotobiotic system that has been developed at NTNU. This system reduces the inherent complexity of microbial control in the wild with a carefully designed protocol beginning with bacteria-free cod larvae, and introducing bacteria stepwise as the larvae develop. Specifically I will address the following three questions: (1) Do different microbial conditions have an effect on the survival, growth and development of the fish larvae? (2) Do probionts and pathogens colonize the same region of the gastrointestinal tract? (3) What happens to the indigenous intestinal microbiota and the host during infection? By adapting these novel technologies in the context of commercial/industrial aquaculture I will not only create long-term collaborations and mutual co-operation between Europe and the U.S., but also significantly contribute to the wellbeing of the commercial aquaculture industry, which is of significant importance to both the Norwegian as well as the European economy. Thus, my proposed efforts will contribute to both European scientific excellence and European commercial competitiveness.