[Frontiers in Bioscience 16, 131-150, January 1, 2011]

Activity rhythms in the deep-sea: a chronobiological approach

Jacopo Aguzzi 1, Joan Batista Company 1, Corrado Costa 2, Paolo Menesatti 2, Jose Antonio Garcia 1, Nixon Bahamon 3, Pere Puig 1, Francesc Sarda 1

1 Instituto de Ciencias del Mar (ICM-CSIC), Paseo Maritimo de la Barceloneta, 37-49. 08003 Barcelona, Spain, 2 AgritechLab - Agricultural Engineering Research Unit of the Agriculture Research Council (CRA-ING), Via della Pascolare, 16. 00016 Monterotondo (Roma), Italy ,3 Operational Oceanography and Sustainability Unit, Centre d'Estudis Avancats de Blanes (CEAB-CSIC). Carrer Acces Cala St. Francesc 14. 17300 Blanes, Spain

TABLE OF CONTENTS

1. Abstract
2. Marine chronobiology and the deep-water ecosystem
3. Internal tides and inertial currents as potential non-photic zeitgebers for deep-sea decapods
4. Activity rhythms in the three-dimensional marine scenario
5. The benthopelagic coupling as a mechanism f indirect entrainment to day-night cycles in the aphotic deep-sea
6. The bases of the entrainment in the deep-sea
7. Photoperiodic responses in the aphotic deep-sea
8. Melatonin in deep-sea decapods
9. The Norway lobster: a chronobiological model for the deep-sea
10. The technology for studying activity rhythms in deep-sea
11. Acknowledgments
12. References

1. ABSTRACT

Ocean waters deeper than 200 m cover 70% of the Earth's surface. Light intensity gets progressively weaker with increasing depth and internal tides or inertial currents may be the only remaining zeitgebers regulating biorhythms in deep-sea decapods. Benthopelagic coupling, exemplified by vertically moving shrimps within the water column, may also act as a source of indirect synchronisation to the day-night cycle for species living in permanently dark areas. At the same time, seasonal rhythms in growth and reproduction may be an exogenous response to spring-summer changes in upper layer productivity (via phytoplankton) or, alternatively, may be provoked by the synchronisation mediated by an endogenous controlling mechanism (via melatonin). In our review, we will focus on the behavioural rhythms of crustacean decapods inhabiting depths where the sun light is absent. Potential scenarios for future research on deep-sea decapod behaviour are suggested by new in situ observation technologies. Permanent video observatories are, to date, one of the most important tools for marine chronobiology in terms of species recognition and animals' movement tracking.