Marine Ecology. ISSN 0173-9565 ORIGINAL ARTICLE Passive acoustic recording of Ophidion rochei calling activity in Calvi Bay (France) Lo€ıc Kever 1, Pierre Lejeune2,Lo€ıc N. Michel2,3 & Eric Parmentier1 1 Laboratoire de Morphologie Fonctionnelle et Evolutive, AFFISH, Institut de chimie, UniversitedeLi ege, Liege, Belgium 2 STARESO Research Station, Revellata Cape, Calvi (Corsica), France 3 Laboratory of Oceanology, MARE Center, University of Liege, Liege, Belgium Keywords Abstract Biological cycle; fish; Ophidiiformes; sound production. Passive acoustic recording (PAR) systems are non-invasive and allow research- ers to collect data over large spatial and/or temporal scales. As fish sounds are Correspondence species-specific and repetitive, PAR can provide a large amount of data about Lo€ıc Kever, Laboratoire de Morphologie spatio-temporal variation in fish distribution and behaviors. Ophidion rochei, Fonctionnelle et Evolutive, AFFISH, Institut de found in the Mediterranean and Black Seas, is a sand-dwelling species, meaning chimie, Baˆ timent B6c, UniversitedeLiege, that the behavior of this cryptic nocturnal fish cannot be observed in the field. B-4000 Liege, Belgium. Fortunately, male O. rochei produce long, multiple-pulsed calls that are easy to E-mail: [email protected] identify. The aim of this study was to determine whether or not male calls are Accepted: 31 August 2015 linked to reproduction behaviors. If so, PAR would allow a detailed description of the seasonal and daily rhythms in O. rochei reproduction behavior. A hydro- doi: 10.1111/maec.12341 phone was deployed from 18 July 2011 to 21 June 2012 and from 7 June 2013 to 2 July 2013 on a sandy area (42°3404800 N, 8°4304300 E) in front of the STARESO research station (NW Corsica). Male sounds were obtained only at night from late spring to early fall. The annual sound production period corre- sponds to the reproductive season of O. rochei. Sound production followed diel cycles: it was sustained for the entire night at the beginning of the sound pro- duction season but limited to shorter periods in the evening during the second half of the season. These differences in daily and seasonal sound production tempo can be used in future recordings to make inter-annual comparisons and estimate the physiological state of the fish. them (e.g. Lobel 1992; Brantley & Bass 1994; Mann & Introduction Lobel 1998; De Jong et al. 2007; Parmentier et al. 2010a, Passive acoustic recording (PAR) systems are key tools to b; Colleye & Parmentier 2012). In addition, some species improve our knowledge in diverse fields of marine biol- are known to produce different kinds of sounds depend- ogy. These techniques are non-invasive and allow ing on the fish behavior (e.g. Gray & Winn 1961; Lugli researchers to collect data over large spatial and/or tem- et al. 1997; Mann & Lobel 1998; Parmentier et al. 2010a). poral scales (Wall et al. 2012, 2013). Moreover, they are As fish sounds are species-specific and repetitive, PAR appropriate for collecting data at night or in dark envi- can provide a large amount of data about spatio-temporal ronments, such as caves and the deep sea, because they variation in fish distribution and behavior (Mann & are not constrained by the amount of available light. Grothues 2009; Wall et al. 2012). Despite numerous During the last several decades, sounds have been behaviors being associated with sound production in recorded from numerous fish species (Slabbekoorn et al. fishes, most of the sounds are closely or indirectly related 2010; Fine & Parmentier 2015) and specific behaviors to behaviors associated with reproduction: territoriality related to these sounds have been described for many of (e.g. Takemura 1984; Tricas et al. 2006; Parmentier et al. Marine Ecology 37 (2016) 1315–1324 ª 2016 Blackwell Verlag GmbH 1315 Ophidion rochei calling activity in Calvi Bay Kever, Lejeune, Michel & Parmentier 2010a), mate courting (e.g. Tavolga 1958; Mann & Lobel female sounds are short with a regular, short duration 1998; Amorim et al. 2003), gamete release (e.g. Lobel pulse period while male sounds (Fig. 1) are much longer, 1992; Hawkins & Amorim 2000; Ladich 2007) and paren- pulsed and show a unique pulse period pattern (Kever tal care (e.g. Longrie et al. 2013). Disturbance calls, by et al. 2012). contrast, have often been reported in captivity but are The biology of O. rochei is still poorly documented, uncommon under natural conditions (Ramcharitar et al. mainly because of its burrowing behavior and nocturnal 2006). way of life, which complicate or prevent direct observa- As sounds are associated with reproductive behavior in tion. Here, we took advantage of the benefits (i.e. oppor- many fish species, spawning season is often paralleled by tunity to study animal behavior during long time periods an increase in calling events (e.g. Brawn 1961; Fish & and at high temporal resolution) of PAR to investigate Cummings 1972; Locascio & Mann 2011). Sound produc- temporal variation of activity periods of male O. rochei tion also varies throughout spawning season; diel cycles throughout the year. Moreover, hypothesizing that sound are generally notable and acoustic activity of many species production is related to reproduction-associated behav- peaks at dusk and/or at dawn (e.g. Mann & Lobel 1995; iors, we explored links between environmental factors Boyle & Tricas 2010; Parmentier et al. 2010b; Longrie such as photoperiod and seawater temperature and the et al. 2013). In some species, it is also affected by other timing of reproduction onset and end-point. All these factors such as moon phases (Mann et al. 2008). data on the cryptic O. rochei will provide precious infor- Photoperiod is generally considered to be the main mation to plan future field studies. environmental factor that determines the onset and dura- tion of reproductive period in fishes (Bromage et al. Material and Methods 2001; Pankhurst & Porter 2003; Migaud et al. 2010). However, the roles of many other factors have also been Recordings of Ophidion rochei sounds demonstrated (Bromage et al. 2001; Pankhurst & Porter 2003; Clark et al. 2005; Migaud et al. 2010). Environmen- A digital spectrogram long-term acoustic recorder (DSG; tal temperature is an important criterion, especially in Loggerhead Instruments, Sarasota, FL, USA) was poikilotherms, notably because of its effects on the gona- deployed during two field campaigns in order to provide dal maturation (Hutchings & Myers 1994) and the neu- the equivalent of a complete year of recording. During À romotor system (Walker 1975). the first campaign, the DSG (À186 dB re 1 VÁlPa 1, Ophidion rochei Muller,€ 1845, is a sand-dwelling species Æ1 dB from 20 Hz to 20 kHz) was deployed almost con- from the Mediterranean and Black Seas (Jardas 1996; tinuously from 18 July 2011 to 21 June 2012 (see Fig. 2A Matallanas & Casadevall 1999). It is found at depths for more details about the actual recording periods). It ranging from a few meters to 150 m, is active at night was positioned at a depth of 40 m, on the sea floor in a and reproduces from June to September (Jardas 1996). In sandy area located in front of the STARESO station this species, both sexes are able to produce sounds; (42°3404800 N, 8°4304300 E; Fig. 3), Corsica. Because of storage limitations, the DSG was programmed to record 5 min per hour at a sample rate of 20 kHz for durations of approximately 3 months, after which the recorder was removed and redeployed two times (see Fig. 2A) by SCUBA divers. During the first year of recording, the hydrophone was not deployed during late June and early July. However, preliminary analyses suggested that this period corre- sponds to the sound production onset. Thus, a mini-DSG (Loggerhead Instruments) was deployed at the same loca- tion from 7 June 2013 to 2 July 2013 (Fig. 2A). It was also set to record 5 min per hour at 20 kHz. The hydro- phone on this device had a slightly higher sensitivity À (À180 dB re 1 VÁlPa 1). Analyses of Ophidion rochei sounds Fig. 1. Waveform of a male Ophidion rochei call recorded in July 2011 in Calvi Bay (France). Gray: long pulse periods, white: short In order to extract Ophidion rochei sounds, all recordings pulse periods. were investigated in AVISOFT SAS-LAB PRO 5.2 (Avisoft 1316 Marine Ecology 37 (2016) 1315–1324 ª 2016 Blackwell Verlag GmbH Kever, Lejeune, Michel & Parmentier Ophidion rochei calling activity in Calvi Bay Fig. 2. Seasonal variation in sound production of male Ophidion rochei in Calvi Bay (France). (A) Timeline showing the periods of actual recordings (light gray) from 1 July 2011 to 30 June 2012 and from the 1 June to 2 July 2013. No data were obtained for the time periods in dark gray. (B) Daily sound production of O. rochei averaged for each month of recordings. Means and standard deviations are shown. (C) Short (gray) and long (black) pulse periods averaged from 10 sounds for each month of recording. Means and standard deviations are shown except for June 2012 because a single sound was recorded during this month. A dashed gray line is drawn at 100 ms to facilitate comparisons. Bioacoustics, Berlin, Germany). A signal was classified as Temporal variations of sound production a male O. rochei sound when it showed the same acoustic The analysis of recording frames was divided into two characteristics as the calls previously recorded for this steps. First, 2 days (day 1 and day 4 of the week) for each species (see Parmentier et al. 2010b; Kever et al. 2012, week of recording were examined in order to search for 2014). The identification is mainly based on the species- and identify every male call. These data allowed the deter- specific pulse period pattern with the pulse period pro- mination of the seasonal variations in sound production gressively increasing in the first part of the sound before using months as treatment groups.