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- Sound production in the Meagre, Argyrosomus regius (Asso, 1801): intraspecific variability associated with size, sex and contextPublication . Pereira, David; Vieira, Manuel; Pousão-Ferreira, Pedro; Candeias-Mendes, Ana; Barata, Marisa; Fonseca, Paulo; Amorim, Maria Clara PessoaMany fish taxa produce sound in voluntary and in disturbance contexts but information on the full acoustic repertoire is lacking for most species. Yet, this knowledge is critical to enable monitoring fish populations in nature through acoustic monitoring.
- Fish sounds and boat noise are prominent soundscape contributors in an urban European estuaryPublication . Vieira, Manuel; Fonseca, Paulo; Amorim, Maria Clara PPassive acoustic monitoring is a valuable tool for non-intrusive monitoring of marine environments, also allowing the assessment of underwater noise that can negatively affect marine organisms. Here we provide for the first time, an assessment of noise levels and temporal soundscape patterns for a European estuary. We used several eco-acoustics methodologies to characterize the data collected over six weeks within May 2016 - July 2017 from Tagus estuary. Biophony was the major contributor dominated by fish vocalizations and the main driver for seasonal patterns. Maritime traffic was the major source of anthropogenic noise, with daily patterns monitored using 1584 Hz third-octave band level. This indicator avoided biophony and geophony, unlike other indicators proposed for the EU Marine Strategy Framework Directive. Furthermore, the frequency overlap between anthropophony and biophony demands precautionary actions and calls for further research. This study provides an assessment that will be useful for future monitoring and management strategies.
- 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.
- Vocal rhythms in nesting Lusitanian toadfish, Halobatrachus didactylusPublication . Vieira, Manuel; Amorim, Maria Clara P; Fonseca, PauloMales of several fish species aggregate and vocalize together, increasing the detection range of the sounds and their chances of mating. In the Lusitanian toadfish (Halobatrachus didactylus), breeding males build nests under rocks in close proximity and produce hundreds of boatwhistles (BW) an hour to attract females to lay their demersal eggs on their nests. Chorusing behaviour includes fine-scale interactions between individuals, a behavioural dynamic worth investigating in this highly vocal fish. Here we present a study to further investigate this species’ vocal temporal patterns on a fine (individual rhythms and male-male interactions) and large (chorus daily patterns) scales. Several datasets recorded in the Tagus estuary were labelled with the support of an automatic recognition system based on hidden Markov models. Fine-scale vocal temporal patterns exhibit high variability between and within individuals, varying from an almost isochronous to an apparent aperiodic pattern. When in a chorus, males exhibited alternation or synchrony calling patterns, possibly depending on motivation and social context (mating or male-male competition). When engaged in sustained calling, males usually alternated vocalizations with their close neighbours thus avoiding superposition of calls. Synchrony was observed mostly in fish with lower mean calling rate. Interaction patterns were less obvious in more distanced males. Daily choruses showed periods with several active calling males and periods of low activity with no significant diel patterns in shallower intertidal waters. Here, chorusing activity was mainly affected by tide level. In contrast, at a deeper location, although tidal currents causes a decrease in calling rate, tide level did not significantly influence calling, and there was a higher calling rate at night. These data show that photoperiod and tide levels can influence broad patterns of Lusitanian toadfish calling activity as in other shallow-water fishes, but fine temporal patterns in acoustic interactions among nesting males is more complex than previously known for fishes.