Biological rhythms in the beach amphipod Talitrus saltator

All living things, from bacteria to humans have biological 'clocks' that enable them to keep time with their surrounding environment which is how we humans tend to wake up at roughly the same time each day! Remarkably, these internal timing mechanisms, which are normally found in the brains of animals, continue to work even when the organism is separated from cues, such as cycles of night and day. Biological clocks are extremely important because organisms can prepare in advance for bouts of activity, growth, mating and other necessary activity at the most appropriate part of the day to avoid predators, find food or mates. Therefore they contribute significantly to the survival and success of all organisms. We now know that the clock mechanisms in different plants and animals that have been studied share striking similarities in the molecules that drive them but, most of our understanding comes from work on a very few 'model organisms' such as the fruit fly. The fruit fly, and nearly all terrestrial organisms, uses the night and day light cycles to synchronise their clocks to local conditions. Consequently their rhythmic behaviour and physiology recurs on a cycle of about 24h. However, marine plants and animals are exposed to many different cyclic events such as the tide coming in and out (tidal clocks; every 12.4h), lunidian (cycles of tidal height; 12.8h) and even changes in tidal range (spring and neap tides) caused by the gravitational pull of the moon and the sun (semilunar clocks; 14d). Although it is well known that many marine species time their behaviour and physiology to these different events, we know very little about their how their internal clocks work. For instance, do they have the same molecular 'cogs' as daily clocks but 'run' at a different speed, or do they have dedicated 'tidal', 'lunidian' or 'semilunar' clocks? This project will decipher the genetic and biochemical basis of cyclic behaviours in the sand-hopper, Talitrus saltator. In the UK this small crustacean emerges from its burrow in the sand at night to feed. It navigates up and down the shore by moving towards the light of the sea horizon in the night but just before dawn it turns back and is drawn to the dark of the land. The emergence and light/dark preferences of the sand-hopper are under clock control and continue to be expressed even if they are kept artificially in total darkness. In the Mediterranean the same species navigate in a different way- by using the position of the sun and moon as their guide. This must also require a sense of time because as the Earth rotates, the sun and the moon appear to move across the sky and the sand-hopper must compensate for this to keep on course. I will compare the UK sand-hoppers to those of the Mediterranean to determine whether their clocks are geared differently or even if they have multiple clocks in their brains. The outcomes of this work could have important impacts on our understanding of biological clocks, how they have evolved and adapted to suit the prevailing environmental conditions and how they contribute to the success of the organism and their interactions with other species.

The proposed project is in the realms of pure science. Nevertheless, the impacts of this work are tangible and real. Beneficiaries of the proposed research include:

1) Basic research groups across multiple biological disciplines- such as biomedical research, pure ecology, evolutionary and population biology. The importance of a more detailed knowledge of biological clocks should not be underestimated. For example, mutations in mammalian clock genes are directly linked to diseases including cancer, obesity, mental illness and sleep disorders. Given the level of conservation of clock molecules across all taxa, findings of the proposed work may have wider implications; defining novel systems and molecules in a non-model animal could, conceivably, transfer into more advanced systems. The project will produce a large volume of genetic data which will be publicly available. These data will be mined by workers across multiple scientific disciplines. In addition, antisera, which are routinely used in basic and applied research, will be produced and made available to bone fide researchers upon direct request to the proposer.
2) Aquaculture organisations and applied research and development in aquaculture. Most, if not all physiological processes are influenced by biological clocks. In arthropods this extends to moulting, reproduction and metabolism etc. Inappropriate or altered light and dark regimes are known to have deleterious effects on marine organisms with implications for commercially cultured species. However, light regimes are only one clock-entraining variable that coastal species are subject to. The proposed work will define clocks that operate with different periods- e.g. 24h, 12.4h, 24.8h etc. This information may be crucial in future attempts to assess the influence of changing environmental parameters on the welfare of commercial species both in captivity and in nature where anthropogenic interference via coastal engineering and lighting will impinge on the fauna and flora. The proposed work will also complement observations reported on the behaviour of wild, commercially harvested species (e.g. the scampi, Nephrops norvegicus). Analysis on the behaviour of this and other marine species has shaped harvesting strategies and catch data interpretation. Providing fine-scale insight into how their clocks function and respond to environmental change may indirectly influence our approach to marine harvest.
3) General Public. The mere concept of biological clocks is inherently fascinating to most people and has been the subject of popular science broadcasts on several occasions (BBC Horizon). Personal experience has taught me that the public are absorbed by the fact that even the most diminutive organisms exhibit an exquisite sense of time that can be used to organise behaviour such as orientation and navigation. Moreover, many apparently have no conception of how various (even common) animals behave and integrate within the ecosystem. Therefore, informing the public about the behaviour of organisms can add to quality of life and potentially even alter behaviour towards animals and each other. One of the first questions I am asked by members of the public when I talk about 'tidal clocks' or 'circadian rhythms' is "how do they do that?" It is therefore imperative that we have the necessary knowledge on these systems to give informed and understandable explanations. The proposed work will provide such detail.