FUTUREFISH: The role of circadian rhythms immunity and infection in enhancing aquaculture

Disease outbreaks currently hinder the economic growth of intensive aquaculture, and increasingly are the key factor leading to closure of fisheries. For indoor fish farms, photoperiod manipulation is used to improve growth and maturation rates. However, how such practices contribute to current disease problems is unknown. Circadian rhythms are ubiquitous to life and central to this rhythmicity is the expression of "clock genes", which regulate rhythms in key biological processes including immune functions. Whilst the intricate links between clock genes and immunity are recognised for mammals, the molecular mechanisms underlying parasite rhythmicity is poorly understood. Therefore, an integrated chronobiological approach to host-pathogen interactions is required to enhance fish production yield. Utilising a multi-model fish-parasite system (Oncorhynchus mykiss-Gyrodactylus, Argulus, Saprolegnia), I will apply behavioural, experimental, qPCR techniques to assess how interactions between light regimes and parasite infections alter activity, clock and immune gene expression, and disease susceptibility. I will employ high-throughput RNA sequencing to reveal rhythmicity of the Gyrodactylus transcriptome in relation to circadian patterns of parasite activity and transmission potential. Finally, using 16S rRNA gene profiling, I will assess the rhythmicity of commensal microbiota of O. mykiss skin and examine how Gyrodactylus infection and antibiotic treatments alters skin microbiomes. For the first time, this will 1) examine the impact of ectoparasites on host circadian rhythms, 2) test the effect of photoperiod manipulation on fish disease susceptibility, and 3) uncover the molecular control of circadian rhythms in parasites. By incorporating rhythmicity of host, commensal microbiota, and parasite, into the first skin interactome, this project will provide for a step change in development of holistic chronobiological approaches to animal health and disease mitigatio