MARE – Centro de Ciências do Mar e do Ambiente, ISPA
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Browsing MARE – Centro de Ciências do Mar e do Ambiente, ISPA by Subject "Acoustic communication"
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- Agonistic sounds signal male quality in the Lusitanian toadfishPublication . Amorim, Maria Clara Pessoa; Conti, Carlotta; Modesto, Teresa; Gonçalves, Amparo; Fonseca, Paulo JorgeAcoustic communication during agonistic behaviour is widespread in fishes. Yet, compared to other taxa, little is known on the information content of fish agonistic calls and their effect on territorial defence. Lusitanian toadfish males (Halobatrachus didactylus) are highly territorial during the breeding season and use sounds (boatwhistles, BW) to defend nests from intruders. BW present most energy in either the fundamental frequency, set by the contraction rate of the sonic muscles attached to the swimbladder, or in the harmonics, which are multiples of the fundamental frequency. Here we investigated if temporal and spectral features of BW produced during territorial defence reflect aspects of male quality that may be important in resolving disputes. We found that higher mean pulse period (i.e. lower fundamental frequency) reflected higher levels of 11-ketotestosterone (11KT), the main teleost androgen which, in turn, was significantly related with male condition (relative body mass and glycogen content). BW dominant harmonic mean and variability decreased with sonic muscle lipid content. We found no association between BW duration and male quality. Taken together, these results suggest that the spectral content of fish agonistic sounds may signal male features that are key in fight outcome.
- 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.
- Brays and bits: Information theory applied to acoustic communication sequences of bottlenose dolphinsPublication . Luís, Ana Rita; Alves, Inês Sofia Carvalho Alves; Sobreira, Filipa Veiga; Couchinho, Miguel Nogueira; Santos, Manuel Eduardo dosAcoustic call sequences are important components of vocal repertoires for many animal species. Bottlenose dolphins (Tursiops truncatus) produce a wide variety of vocalizations, in different behavioural contexts, including some conspicuous vocal sequences – the ‘bray series’. The occurrence of brays is still insufficiently documented, contextually and geographically, and the specific functions of these multi-unit emissions are yet to be understood. Here, acoustic emissions produced by bottlenose dolphins in the Sado estuary, Portugal, were used to provide a structural characterization of the discrete elements that compose the bray series. Information theory techniques were applied to analyse bray sequences and explore the complexity of these calls. Log-frequency analysis, based on bout criterion interval, confirmed the bout structure of the bray series. A first-order Markov model revealed a distinct pattern of emission for the bray series’ elements, with uneven transitions between elements. The order in these sequential emissions was not random and consecutive decreases in higher order entropy values support the notion of a well-defined structure in the bray series. The key features of animal signal sequences here portrayed suggest the presence of relevant information content and highlight the complexity of the bottlenose dolphin’s acoustic repertoire.
- Effects of temperature on sound production in the painted goby Pomatoschistus pictusPublication . Vicente, Joana R.; Fonseca, Paulo Jorge; Amorim, Maria Clara PessoaThe painted goby Pomatoschistus pictus emits courtship sounds (drums) that are important in reproductive outcome. The effect of temperature (14–22 °C) on courtship drum features was characterised. Pulse period (or rate) was linearly related with temperature (R2 = 0.83) presenting a Q10 of 2.13. Pulse period decreased by 1.95 ms per 1 °C and varied from 34 ms to 18.6 ms within the studied temperature range. Sound duration changed concomitantly from 1128 ms to 658 ms. Changes in sound duration were due to pulse period rather than pulse number, since the latter was not affected by temperature. Pulse duration was similarly affected by temperature, decreasing by 0.3 ms per 1 °C (R2 = 0.51, Q10 = 1.45) and changing from 10.0 ms at 14 °C to 7.5 ms at 22 °C. Drum emission rate, sound amplitude, fatigue and dominant frequency were also not related to temperature. The temperature effect on pulse rate likely reflects temperature-dependence of the vocal central pattern generator as observed in other animals. In contrast, shorter pulse durations likely result from temperature effects at the peripheral level of the vocal system, as muscle twitches typically shorten with rising temperatures. Because pulse rate is likely important in mate choice and conspecific recognition in fish, including P. pictus, future studies are needed to understand if temperature-related changes in pulse rate are coupled with changes in mate preference as found in insects and anurans.
- Noise can affect acoustic communication and subsequent spawning success in fishPublication . Jong, Karen de; Amorim, Maria Clara Pessoa; Fonseca, Paulo João; Fox, Clive J.; Heubel, Katja U.There are substantial concerns that increasing levels of anthropogenic noise in the oceans may impact aquatic animals. Noise can affect animals physically, physiologically and behaviourally, but one of the most obvious effects is interference with acoustic communication. Acoustic communication often plays a crucial role in reproductive interactions and over 800 species of fish have been found to communicate acoustically. There is very little data on whether noise affects reproduction in aquatic animals, and none in relation to acoustic communication. In this study we tested the effect of continuous noise on courtship behaviour in two closely-related marine fishes: the two-spotted goby (Gobiusculus flavescens) and the painted goby (Pomatoschistus pictus) in aquarium experiments. Both species use visual and acoustic signals during courtship. In the two-spotted goby we used a repeated-measures design testing the same individuals in the noise and the control treatment, in alternating order. For the painted goby we allowed females to spawn, precluding a repeated-measures design, but permitting a test of the effect of noise on female spawning decisions. Males of both species reduced acoustic courtship, but only painted gobies also showed less visual courtship in the noise treatment compared to the control. Female painted gobies were less likely to spawn in the noise treatment. Thus, our results provide experimental evidence for negative effects of noise on acoustic communication and spawning success. Spawning is a crucial component of reproduction. Therefore, even though laboratory results should not be extrapolated directly to field populations, our results suggest that reproductive success may be sensitive to noise pollution, potentially reducing fitness.
- Reproductive success in the Lusitanian toadfish : Influence of calling activity, male quality and experimental designPublication . Amorim, Maria Clara Pessoa; Conti, Carlotta; Santos, Carla Sousa; Novais, Bruno; Gouveia, Maria D.; Vicente, Joana R.; Modesto, Teresa; Gonçalves, Amparo; Fonseca, Paulo JorgeAcoustic signals are sexual ornaments with an established role on mate choice in several taxa, but not in fish. Recent studies have suggested that fish vocal activity may signal male quality and influence male's reproductive success but experimental evidence is lacking. Here we made two experiments to test the hypothesis that vocal activity is essential for male breeding success in a highly vocal fish, the Lusitanian toadfish. We first compared the reproduction success between muted and vocal males. In a second experiment we related male reproduction success with acoustic activity and male quality, including biometric, condition and physiological features. As a proxy for reproductive success we tallied both total number and number of sired eggs, which were correlated. Muting experiments showed that successful mating was dependent on vocalizing. In addition, the number of eggs was positively associated with the male's maximum calling rate. In the second experiment male's reproductive success was positively associated with male condition and negatively related with circulating androgen levels and relative gonad mass, but was not associated with vocal activity. Differences in results may be related with nest design which could have influenced mate choice costs and intra-sexual competition. In the muting experiment nests had a small opening that restrained the large nest-holder but allowed smaller fish, such as females, to pass while in the second experiment fish could move freely. These experiments suggest that a combination of factors, including vocal activity, influence reproductive success in this highly vocal species.
- Vocal differentiation parallels development of auditory saccular sensitivity in a highly soniferous fishPublication . Vasconcelos, Raquel Ornelas; Alderks, Peter W.; Ramos, Andreia; Fonseca, Paulo Jorge; Amorim, Maria Clara Pessoa; Sisneros, Joseph A.Vocal differentiation is widely documented in birds and mammals but has been poorly investigated in other vertebrates, including fish, which represent the oldest extant vertebrate group. Neural circuitry controlling vocal behaviour is thought to have evolved from conserved brain areas that originated in fish, making this taxon key to understanding the evolution and development of the vertebrate vocal-auditory systems. This study examines ontogenetic changes in the vocal repertoire and whether vocal differentiation parallels auditory development in the Lusitanian toadfish Halobatrachus didactylus (Batrachoididae). This species exhibits a complex acoustic repertoire and is vocally active during early development. Vocalisations were recorded during social interactions for four size groups (fry: <2 cm; small juveniles: 2-4 cm; large juveniles: 5-7 cm; adults >25 cm, standard length). Auditory sensitivity of juveniles and adults was determined based on evoked potentials recorded from the inner ear saccule in response to pure tones of 75-945 Hz. We show an ontogenetic increment in the vocal repertoire from simple broadband-pulsed 'grunts' that later differentiate into four distinct vocalisations, including low-frequency amplitude-modulated 'boatwhistles'. Whereas fry emitted mostly single grunts, large juveniles exhibited vocalisations similar to the adult vocal repertoire. Saccular sensitivity revealed a three-fold enhancement at most frequencies tested from small to large juveniles; however, large juveniles were similar in sensitivity to adults. We provide the first clear evidence of ontogenetic vocal differentiation in fish, as previously described for higher vertebrates. Our results suggest a parallel development between the vocal motor pathway and the peripheral auditory system for acoustic social communication in fish.