Preliminary characterization of the acoustic signals emitted by the crab Neohelice granulata (Brachyura, Varunidae) in different social layouts

FILICIOTTO F; SAL MOYANO M. P.; CORRIAS V; LORUSSO M; HIDALGO F; BAZTERRICA MA; SALVATORE M; BUSCAINO G; GAVIO M. A.

Dublin

Conferencia; The fourth International Conference on "The Effects of Noise on Aquatic Life"; 2016

Beginning in the late 1989s, an explosion of works involved the ecology, physiology, toxicology and behaviour of the burrowing crab Neohelice granulata, considered as a model species in a variety of biological fields, even if, until now there are no studies about its acoustic emissions.The aim of this study was to characterize preliminarily the acoustic signals emitted by the crab N. granulata, evaluating them in different social layouts.The study was conducted in the Estación Costera J.J. Nágera of the Universidad Nacional Mar del Plata, Argentina. Crabs were collected by hand from the field and, after the acclimatization phase, were moved to a circular fibre-glass tank adopting the following trial configuration: 1 male alone; 1 female alone; 1 male and 1 female; 2 males and 1 female, 2 females and 1 male (each trial consisted of 3 replicates). In total, 15 experimental trials were performed using 30 specimens of N. granulata of which 15 males (carapace width of 30.37 ± 3,1 mm; Mean ± SD) and 15 females (carapace width of 27.19 ± 3,2 mm; Mean ± SD). The trials consisted of 1 hour of acoustic recording using a calibrated hydrophone (model 8104, Brüel & Kjær) with a sensitivity of −205.6 ± 4.0dBre1VμPa?1 in the 0.1Hz?80kHz frequency band. The hydrophone was connected to a digital acquisition card (USGH416HB, Avisoft Bioacoustics) managed by Avisoft Recorder USGH software. Pulse trains and single pulses were analysed using the routine Pulse Train Analysis (Avisoft-SASLab Pro) automatic method. Overall, 75 pulse trains containing 552 single pulses were recorded during the trials. Signals from crabs showed the following acoustic parameters expressed as median ± 10th to 90th percentiles: pulse train duration of 0.3 ± 0.07-2.22 sec.; 5 ± 3-10 number of pulses in the pulse train; pulse rate of 11.9 ± 4.5-29.63 Hz, determined as the ratio of the number of pulses and the duration of the pulse train; 4.33 ± 2.6-6.2 kHz in peak frequencies; 179.32 ± 174.56-191.87 dB re 1 µPa in peak amplitude.No signals were recorded from crabs evaluated alone and all the acoustic emissions were observed in trials with grouped animals (without statistical differences in the number of signals among the group layouts), allowing us to assume a social/reproductive role of the acoustic signals in this crab species. However, further studies are needed in order to analyse the difference of signals structure depending on sex and animal size.