Gene function in Antarctic krill: determining the role of clock-genes in synchronised behavioural patterns

Antarctic krill form an important part of the oceanic ecosystem, acting as predators on plankton and as a food source for a variety of animals including fish, sea birds and aquatic mammals. They migrate in a predictable manner each day, moving to the surface at night to feed and to greater depths during the day to avoid visually guided predators. Krill also synchronise their spawning and moulting cycles to maximise reproductive success. It is not known how these cycles are controlled, but it is likely that they are regulated by 'clock' genes. The circadian clock is an inbuilt mechanism by which the body controls many aspects of behaviour and physiology that oscillate with a 24-hour period, including the sleep-wake cycle, metabolic functions, and activity rhythms. The molecular basis of these cycles was originally described in fruit flies but has since been demonstrated in all animals investigated thus far. Interestingly, the circadian clock maintains the same general design but with remarkable species-specific differences. In addition to the circadian timekeeper, other clock mechanisms exist that control different types of periodicity, such as inter-tidal and lunar cycles, although their molecular architecture is still unknown. The aim of this project is to describe for the first time how daily migrations and monthly spawning-moulting cycles of krill are controlled by clock genes. This will involve a series of behavioural observations, to describe locomotor activity under controlled conditions, and molecular investigations to identify the clock genes associated with the daily and monthly rhythmic phenotypes and their pattern of expression. It has recently been shown that the abundance of krill has dramatically decreased in the Antarctic Ocean over the last 80 years and that this decline is correlated with a reduction in the extent of the sea ice due to global warming. In view of the importance of the species and the apparent threat from changes in climate, it is necessary that we fully understand krill behaviour so that we can monitor how they adapt to climatic changes. In particular, regular recruitment to the stock is necessary to maintain population levels so an understanding of the reproductive cycle is essential. In our work we will use both standard and state of the art methodologies and create new resources that we will make available to the scientific community. It is likely that other pelagic crustaceans have close sequence similarity with homologous krill genes. This will enable others to build on our work, both in the pursuit of scientific aims and also in relation to the farming industry.