O12- Automatic detection of Meager’s (Argyrosomus regius) chorusing activity reveals natural rhythms and noise impacts
Manuel Vieira, Departamento de Biologia Animal and cE3c – Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Portugal; MARE – Marine and Environmental Sciences Centre, ISPA-Instituto Universitário, Lisboa.
- Clara P. Amorim, MARE – Marine and Environmental Sciences Centre, ISPA-Instituto Universitário, Lisboa; Faculdade de Ciências, Universidade de Lisboa, Portugal.
Tiago A. Marques, Centre for Research into Ecological and Environmental Modelling, , University of St Andrews, St Andrews, Scotland; Departamento de Biologia Animal, Centro de Estatística e Aplicações, Universidade de Lisboa, Portugal.
Paulo J. Fonseca, Departamento de Biologia Animal and cE3c – Centre for Ecology, Evolution and Environmental Changes; Faculdade de Ciências, Universidade de Lisboa, Portugal.
Many fish species rely on acoustic communication to fulfil several functions such as advertisement and mediation of social interactions. Therefore, Passive Acoustic Monitoring (PAM) can be a valuable tool to monitor activity and distribution of important soniferous fish species such as the meagre (Argyrosomus regius). However, PAM often involves extensive sound recordings and consequently automatic methods are invaluable tools to detect and extract relevant biological information. This study assesses the impact of boat passages on the vocal behaviour the meagre over four months in the Tagus estuary (Portugal). The Tagus estuary is an important breeding site for this species, but also holds important maritime harbours and a network of ferryboat connections. We used an automatic pattern-recognition methodology based on Hidden Markov Models to assess the occurrence of meagre choruses from continuous recordings. We further tested the impact of boat passages on meagre choruses by quantifying changes in chorus energy assessed with power spectral density. Meagre choruses were observed from 13h30 to 05h00 and were dominated by long-grunts and series of isolated pulses. The chorus onset was dependent on minimum water temperature, daytime length and lunar phase (generalized additive model, R2 = 0.74). Minimum temperature had the highest explanatory power (R2 = 0.66), with a non-linear correlation with chorus onset. On average we observed a significant reduction in the chorus energy related to the ferryboat passages. This study shows that PAM can be used to obtain relevant information on the meagre spatial and temporal use of spawning areas, and to assess the impact of boat noise on fish behaviour.