Bioacoustics The International Journal of Animal Sound and its Recording, 1996, Vol. 6, pp. 265--272 0952-4622/96 $10 © 1996 AB Academic Publishers SOUND PRODUCTION IN THE BLUE-GREEN DAMSELFISH, CHROMIS VIRIDIS (CUVIER, 1830) (POMACENTRIDAE) MARIA CLARA PESSOA DE AMORIM S.O.A.E.F.D., Marine Laboratory, Aberdeen AB9 BDB, Scotland, UK ABSTRACT Sound production is widespread in coral reef fish of the family Pomacentridae. As commonly found in other teleosts, damselfish emit calls in agonistic and courtship contexts. In this paper, evidence of sound production by the blue-green damselfish Chromis viridis is presented for the first time. The recorded sounds consisted of clicks produced during agonistic interactions. Key words: sound production, agonistic behaviour, Chromis, damselfish, Pomacentridae INTRODUCTION It is known that acoustic signalling is widely used by fish during courtship and agonistic activities (Myrberg 1981). Also, laboratory and field studies have shown that sound production in fish may have a communicative function and contribute to both survival and reproductive success (see Hawkins and Myrberg 1983 and Bass 1990 for a review). Some of these studies have focused on the coral reef fish from the family Pomacentridae, in particular of the genus Pomacentrus, and have produced evidence that sound emission has indeed a fundamental role in the outcome of courtship and territorial defence in damselfish (Myrberg 1972, Myrberg et al. 1978, Spanier 1979, Takemura 1983, Myrberg and Riggio 1985, Myrberg et al. 1986, Kenyon 1994). In the present paper, a first description is given of the sounds produced by the blue-green damselfish Chromis viridis-often incorrectly named as C. caerulea (Randall et al. 1985). METHODS Sounds from 5 blue-green adult damselfish, ranging in size from 8 to 9 em TL, were recorded at the Vasco da Gama Aquarium exhibition 266 centre in Lisbon, Portugal. Recordings were made when the Aquarium was closed to the public or at periods of low public attendance (i.e. when extraneous noise conditions allowed recording). Fish were obtained from a local tropical fish shop and included both males and females. Fish were kept in a glass display tank, 68 (h) x 35 (w) x 160 em (maximum length), together with other tropical fish: Amphiprion ocellaris; hybrids of A. frenatus and A. clarkii (Pomacentridae); Halichoeres trispilus (Labridae); Anampses chrysocephalus (Labridae); Pseudanthias squamipinnis (Serranidae); Nemateleotris magnificus (Eleotridae). The aquarium was supplied with hard coral, rocks and anemones, and also with biological filters and aeration. Fish were fed with brine shrimp. Before the beginning of each recording session, aeration was stopped. The fish were monitored during three different days for approximately 60 min, and the behaviour accompanying each sound emission was noted down. Particular behaviours identified the individual producing sounds, and only sounds that could be definitely attributed to the blue-green damselfish were considered for analysis, since there were other sound-producing species in the tank. Sounds were obtained with a hydrophone (MS.83 Sound Range Hydrophone, Plessey Ltd.) with a sensitivity of -100 dB re 1V/)lbar and with a flat frequency response up to 40 kHz, placed approximately in the middle of the experimental tank; amplified and filtered with a low noise amplifier (Brookdeal, model 450), set to 30 dB gain, with highand low-pass filters set at 10Hz and 10kHz respectively; and recorded with a professional digital audiotape recorder (DAT) (Casio, model DA-1). A Loughborough Sound Images Workstation (version 2.0; Metagraphics Software Corporation ©), with IBM-compatible hardware (Elonex PC-333), was used for sound analysis. The following sound features were measured: peak frequency (frequency at the highest sound amplitude, Hz) (filter bandwith-125 Hz); pulse and sound duration (msec); number of pulses in a sound; pulse peak to peak interval (interval between the peak amplitude of two pulses, msec); interval between sounds (msec) when sounds were produced in bursts. RESULTS C. viridis produced click-like sounds during agonistic interactions (Table 1). Although there were several fish species in the aquarium, most of the observed agonistic interactions and sound production were directed to conspecifics (93.3%). The calls were produced in bursts of 1 to 22 clicks (n = 12; mean = 5.58; S.D. = 5.68-Figure 1), during chases-a behaviour which was seen to occur very frequently in the 267 TABLE 1 Sample size (n), mean, standard deviation (S.D.), minimum (Min) and maximum (Max) of the physical features of click sounds produced by captive Chromis viridis (see text for explanations). Sound duration (msec) Pulse duration (msec) No. of pulses Pulse peak-peak interval (msec) Peak frequency (Hz) Interval between sounds (msec) 4 n Mean S.D. Min Max 62 62 62 29 62 45 15.69 7.94 2.11 7.03 709.02 251.88 7.35 2.71 1.19 1.64 92.8 398.57 5.8 4.9 1 4.7 573 14.9 33.3 20.8 5 9.8 936 1693.5 ~- 3 I I! l 0 <]) "0 .8 .... as < 100 msec. Figure 1. Sonogram and oscillogram of a series of clicks produced by Chromis viridis. The filter bandwidth used for the sonogram was 125 Hz. 268 aquarium. Very often these chases ended in mutual parallel displays or in the fleeing of the chased fish. Clicks were most frequently single pulses, but they could be made up to two or more pulses (Figures 2 and 3). Multiple-pulsed clicks presented a typical pulse period (peak-peak interval) of approximately 7 msec, as can be seen in Figure 4. It should be noted that because recordings were carried out in a small tank, the pulse structure of the sounds analysed may have been (f) .:::.:. .5:! 20 <J "-- 0 0 ....,.. "'- 10 2 4 3 No. of pulses per click 5 Figure 2. Distribution of pulse numbers in click sounds. a b 10 msec Figure 3. Oscillograms of clicks made up of 1 and 2 pulses (a and b respectively). 269 _,..-... 'J <1> -c: 10 (J) E ro a 2c 6 T -r-- .T T ..::..: ,-;:; (]) Q.. I ..::..: 4 ro <1> Q.. <1> 2 N !£!. :::; CL. =9 N = 15 N =3 N =2 0 2 3 4 5 No. of pulses in a sound Figure 4. Pulse peak-peak interval (msec) of clicks with 2, 3, 4 and 5 pulses. affected by possible reverberation from the tank walls (Parvulescu 1967). DISCUSSION This paper presents the first report on sound production in the bluegreen damselfish. C. viridis uttered sounds during agonistic interactions, as found for other damselfish (Table 2). Several authors provide information, with more or less detail, on agonistic sounds of several species of Amphiprion (e.g. Schneider 1964, Allen 1975, Takemura 1983, Chen and Mok 1988), while Myrberg (1972) and Luh and Mok (1986) respectively describe the sounds of Pomacentrus partitus and Dascillus trimaculatus. One to three types of sounds are quoted for each species, not always following the same terminology, thus making it difficult to compare data between authors. Of the various sounds referred to in Table 2, A. clarkii and A. frenatus chirps (Chen and Mok 1988) are probably similar sounds to the clicks described by Allen (1975) for both A. chrysopterus and A. perideraion and to Schneider's threatening sounds (Schneider 1964). The clicks of C. viridis analysed in the present work seem also to fall into the same category of sounds, when taking into account the sound's frequency structure and the number of sounds in a call. However, unlike the previous sounds, the clicks of C. viridis may present more than one pulse, and the pulse duration was also considerably shorter than for the others. Of the multiple-pulsed aggressive sounds found in the literature, only the chirps of D. ~ TABLE 2 -J 0 Sounds produced by damselfish during aggressive encounters. Species Sound type A. clarkii, "Threatening sounds" "Fighting sounds" "Shaking sounds" A. polymnus, A. frenatus, A. ocellaris No. of pulses Pulse duration (msec) Main frequency (kHz) No. of sounds in a call Context of sound production Author 1 (?) 25--30 0.6 4-12 Fighting over an anemone Schneider (1964) ? ? 45--60 ? ? ? ? Threat, attack, submission Allen (1972) (1972) Agomstic displays Chen & Mok (1988) ? Threat. dash. bite Takemura (1983) A. perideraion Clicks Grunts (only a) 1 ? 35--45 100 <1 0.6 3--15 1-3 A. clarkii (b), A. frenatus (c) Pops Chirps 1 1 80(b)/50(c) 50 <3 <1.5(b)/<1(c) 1-2 1-17(b)/1-17(c) 1 1 1 1 ? ? ? 56 A. chrysopterus (a), A. ocellaris, A. frenatus, A. clarkii. A. melanopus, A. polymnus, A. sandaracinus ? P. partitus Pops D. trimaculatus Pops Chirps Grunts ? 64 ? ? 0.5 <8 ? ? ? 1 20-40 0.6--1.5 1 Frontal-thrust. chase, circle Myrberg (1972) 1 13--55 " 4-8 " " ? ? ? Threat, submission 3--6 3--6 Luh & Mok (1986) " 271 trimaculatus present a similarly small pulse interval (8-16 msec) (Luh and Mok 1986) to the one found for C. viridis. Most of the multiplepulsed damselfish sounds are produced during courtship and present larger pulse intervals; for example, the chirps of P. partitus show a pulse interval of 59-90 msec when recorded under laboratory conditions (Myrberg 1972). Given the present findings, it would be interesting to compare the features of the clicks of C. viridis with the features of other agonistic sounds and also with courtship sounds produced by either the same or closely related species (genus Chromis). In addition, more detailed acoustic studies, including the playback of natural and manipulated sounds, are required to gain a better understanding of the role of sound production in the social communication system of Chromis and of the Pomacentridae family. ACKNOWLEDGEMENTS This work is included in a project financed by Programme "Ciencia" (BD/2346/92-IG) (Portugal). I am grateful to Fatima Gil for her helpfulness and to the director of Vasco da Gama Aquarium (Lisbon, Portugal) for allowing this study to take place. I am also grateful to Prof. Hawkins and Dr. Mackie for reviewing this paper and to the two referees for their helpful comments and suggestions. REFERENCES Allen, G. R. (1975). The Anemonefishes. Their classification and biology, 2nd ed. T.F.H. Publications; Neptune City. Bass, A. H. (1990). Sounds from the intertidal zone: vocalizing fish. Bioscience, 40, 249258. Chen, K.-C. & Mok, H.-K. (1988). Sound production in the anemonefishes Amphiprion clarkii and A. frenatus (Pomacentridae), in captivity. Japan J. Ichthyol., 35, 90-97. Hawkins, A. D. & Myrberg, A. A., Jr. (1983). Hearing and sound communication underwater. In Bioacoustics. A comparative approach (B. Lewis, ed.). Academic Press; London, pp. 347-405. Kenyon, T. N. (1994). The significance of sound interception to males of the bicolor damselfish, Pomacentrus partitus, during courtship. Env. Biol. Fish., 40, 391-405. Luh, H. K. & Mok, H. K. (1986). Sound production in the domino damselfish, Dascyllus trimaculatus (Pomacentridae), under laboratory conditions. Japan. J. Ichthyol., 33, 70-74. Myrberg, A. A., Jr. (1972). Ethology of the bicolor damselfish, Eupomacentrus partitus (Pisces: Pomacentridae): a comparative analysis of laboratory and field behaviour. Anim. Behav. Monogr., 5. 199-283. Myrberg, A. A., Jr., Spanier, E. & Ha, S. J. (1978). Temporal patterning m acoustical communication. In Contrasts in Behaviour (E. S. Reese & F. J. Lighter, eds). John Wiley & Sons; New York, pp. 137-179. Myrberg, A. A., Jr. (1981). Sound communication and interception in fishes. In Hearing 272 and sound communication in fishes (W. N. Tavolga, A. N. Popper & R. R. Fay, eds), Springer-Verlag; New York, pp. 395-425. Myrberg, A. A., Jr. & Riggio, R. J. (1985). Acoustically mediated individual recognition by a coral reef fish (Pomacentrus partitus). Anim. Behav., 33, 411-416. Myrberg, A. A., Jr., Mohler, M. & Catala, J. D. (1986). Sound production by males of a coral reef fish (Pomacentrus partitus): its significance to females. Anim. Behav., 34, 913-923. Parvulescu, A. (1967). The acoustics of small tanks. In Marine Bio-acoustics, Vol. 2 (W. N. Tavolga, ed). Pergamon Press; Oxford, pp. 7-13. · Randall, J. E., Bauchot, M.-L. & Desoutter, M. (1985). Chromis viridis (Cuvier, 1830), the correct name for the Indo-Pacific damselfish previously known as C. caerulea Cuvier, 1830 (Pisces: Pomacentridae). Cybium, 9, 411-413. Schneider, H. (1964). Bioakustische Untersuchungen an Anemonenfischen der Gattung Amphiprion (Pisces). Z. Morph. Okol. Tiere, 53, 453-474. Spanier, E. (1979). Aspects of species recognition by sound in four species of damselfishes, genus Eupomacentrus (Pisces: Pomacentridae). Z. Tierpsychol., 51, 301-316. Takemura, A. (1983). Studies on underwater sound-VIII Acoustical behaviour of clownfishes (Amphiprion spp.). Bull. Fac. Fish. Nagasaki Univ., 54, 21-27. Received 12 October 1995, revised 27 November 1995 and accepted 3 December 1995