An automated multi-flume actograph for the study of behavioral rhythms of burrowing organisms

Abstract

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 current 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 customized 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/m2/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