An automated multi-flume actograph for the study of behavioral rhythms of burrowing organisms V. Sbragaglia a, ⁎, J. Aguzzi a , J.A. García a , D. Sarriá b , S. Gomariz b , C. Costa c , P. Menesatti c , M. Vilaró a , A. Manuel b , F. Sardà a a Marine Science Institute, (ICM-CSIC) – Passeig Marítim de la Barceloneta 37–49, Barcelona 08003, Spain b Technological center of Vilanova i la Geltrú (SARTI), Rambla de l'Exposició s/n, Vilanova i la Geltrú 08800, Spain c Consiglio per la Ricerca e la sperimentazione in Agricoltura, [Unità di ricerca per l'ingegneria agraria] – Via della Pascolare 16, Monterotondo Scalo 00015, Italy abstract article info Article history: Received 17 January 2013 Received in revised form 18 March 2013 Accepted 24 May 2013 Available online 16 June 2013 Keywords: Actograph Automated video-imaging Behavioral rhythms Blue light Internal tides Nephrops norvegicus In this study, we present and test the functioning of a automated multi-flume actograph that is able to simulate concomitant geophysical cycles (day-night and hydrodynamic cycles) characterizing the benthic environment of continental margins. The burrowing Norway lobster (Nephrops norvegicus, L.) was used to test the functioning of the device. The system is endowed with pumps and a pipe system for periodical cur- rent flow generation. Monochromatic blue light cycle (472 nm) was provided by submergible LED's lighting strips. Locomotor activity of 8 individuals was tracked by 4 HD video cameras during a 10 days trial. A cus- tomized automated video-imaging protocol in MATLAB calculated displacement of animals (cm/min). The functioning of the system was tested simulating an Atlantic continental shelf scenario (i.e. light intensity of 4 · 10 -3 μE/m 2 /s and current flow at 10 cm/s). Robust time series outputs of nocturnal phase were reported, with the first laboratory evidence of the influence of current flow on burrow emergence of the species. Water flow increase inhibited lobster movement generating a dual reaction in relation to their burrow emergence phase. The method presented here could be pivotal to study unknown aspects of Norway lobster ecology. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Biological rhythms are defined as the recurrence of any event within a biological system at more-or-less regular intervals (Kalmus, 1935). Rhythms implying a modulation by a biological clock are defined as endogenous, while all the rhythms originating by a mere response to a habitat fluctuation are defined exogenous (Aschoff, 1960; Pittendrigh, 1960). One of the most studied areas of biological clock regulation is behavior. Temporal patterning has been detected in all animals studied so far (Refinetti, 2006). Behavior of marine species can be measured as locomotor/swimming activity and it is an important parameter to be studied in order to increase our knowledge about temporal changes in community composition and thus apparent biodiversity (Aguzzi et al., 2012). In this scenario, laboratory tests on animals' reaction to simulated geophysical cycles are important to understand the temporal regulation of behavior upon day-night (24 h) and tidal cycles (12.4 h) (Naylor, 2010; Palmer, 1974; Reebs, 2002). Crustaceans play a central role in laboratory research on behavioral rhythms of marine species and a wide numbers of technological approaches have been used for tracking their locomotor activity: stylus recording on rotating drums (Naylor, 1958), photo-electric cells (Williams and Naylor, 1969), infra-red light (Aguzzi et al., 2008; Naylor and Atkinson, 1972; Naylor and Williams, 1984), radio frequency identification (Aguzzi et al., 2011a), racetracks and running wheels (Jury et al., 2005), rotational displacement transducers (Johnson and Tarling, 2008), time-lapse photography (Enright, 1965; Klapow, 1972) and more lately automated video-imaging (Aguzzi et al., 2009a; Menesatti et al., 2009). The latter is gaining an increasing attention, due to progresses in automation and efficiency of objects recognition (Obdrzalek and Matas, 2002). Independently of the device used, most of laboratory research with crustaceans has been carried out with intertidal shallow water species exposed, light cycles apart, to oscillations in water presence/ absence, temperature, hydrostatic pressure, salinity, and turbulence (e.g. Chabot et al., 2008; Enright, 1965; Hastings, 1981; Jones and Naylor, 1970; Palmer, 1995; Taylor and Naylor, 1977; Williams and Naylor, 1969). Conversely, behavioral rhythms in deep water conti- nental margin species have been mostly ignored (Naylor, 2005). Locomotor activity of deep water species could also be regulated by the synergic interplay of day-night and hydrodynamic cycles (e.g. in- ternal tides), but data on these aspects are scant (Aguzzi et al., 2009b, 2010; Wagner et al., 2007). In this study, we present and demonstrate the functioning of a multi- flume automated actograph that can simulate and reproduce complex scenarios of concomitant day-night and hydrodynamic cycles (e.g. inter- nal tides). We tested the device by tracking, using automated video imaging, the burrow emergence rhythm of a commercially important Journal of Experimental Marine Biology and Ecology 446 (2013) 177–185 ⁎ Corresponding author. Tel.: +34 932309500; fax: +34 932309555. E-mail address: sbragaglia@icm.csic.es (V. Sbragaglia). 0022-0981/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jembe.2013.05.018 Contents lists available at SciVerse ScienceDirect Journal of Experimental Marine Biology and Ecology journal homepage: www.elsevier.com/locate/jembe