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- Assessment of fighting ability in the vocal cichlid Metriaclima zebra in face of incongruent audiovisual informationPublication . Amorim, Maria Clara Pessoa; Fonseca, Paulo; Mathevon, Nicolas; Beauchaud, MarilynInformation transfer between individuals typically depends on multiple sensory channels. Yet, how multi-sensory inputs shape adaptive behavioural decisions remains largely unexplored. We tested the relative importance of audio and visual sensory modalities in opponent size assessment in the vocal cichlid fish, Metriaclima zebra, by playing back mismatched agonistic sounds mimicking larger or smaller opponents during fights of size-matched males. Trials consisted in three 5-min periods: PRE (visual), PBK (acoustic+visual) and POST (visual). During PBK agonistic sounds of smaller (high frequency or low amplitude) or larger (low frequency or high amplitude) males were played back interactively. As a control, we used white noise and silence. We show that sound frequency but not amplitude affects aggression, indicating that spectral cues reliably signal fighting ability. In addition, males reacted to the contrasting audio-visual information by giving prevalence to the sensory channel signalling a larger opponent. Our results suggest that fish can compare the relevance of information provided by different sensory inputs to make behavioural decisions during fights, which ultimately contributes to their individual fitness. These findings have implications for our understanding of the role of multi-sensory inputs in shaping behavioural output during conflicts in vertebrates.
- Boat noise affects meagre (Argyrosomus regius) hearing and vocal behaviourPublication . Vieira, Manuel; Beauchaud, Marilyn; Amorim, Maria Clara P; Fonseca, PauloAquatic noise has increased in last decades imposing new constraints on aquatic animals' acoustic communication. Meagre (Argyrosomus regius) produce loud choruses during the breeding season, likely facilitating aggregations and mating, and are thus amenable to being impacted by anthropogenic noise. We assessed the impact of boat noise on this species acoustic communication by: evaluating possible masking effects of boat noise on hearing using Auditory Evoked Potentials (AEP) and inspecting changes in chorus sound levels from free ranging fish upon boat passages. Our results point to a significant masking effect of anthropogenic noise since we observed a reduction of ca. 20 dB on the ability to discriminate conspecific calls when exposed to boat noise. Furthermore, we verified a reduction in chorus energy during ferryboat passages, a behavioural effect that might ultimately impact spawning. This study is one of few addressing the effects of boat noise by combining different methodologies both in the lab and with free ranging animals.