Passive monitoring of phenological acoustic patterns reveals the sound of the camouflage grouper, Epinephelus polyphekadion

Abstract

1. Passive acoustic monitoring (PAM) is a non-invasive technique that uses hydrophones to monitor populations and ecosystem dynamics. Although many applications of PAM have been developed in recent years, it has never been used to identify a calling marine species.2. The south pass of Fakarava Atoll, French Polynesia, hosts spawning events of many reef fish species, including the camouflage grouper Epinephelus polyphekadion, with a spawning aggregation abundance exceeding 17 000 individuals during the full moons of June and July.3. The current study aimed to use PAM to distinguish camouflage grouper sounds among the vocal activities of all fish recorded during the aggregation periods. Audio recordings analysis resulted in the identification of 29 sound types, some of which showed diel and lunar patterns.4. Temporal analysis of these sounds in relation to spawning activities allowed the identification of camouflage grouper calls. These calls can be described as a single pulse or a series of 'boom(s)' with a pulse duration of ~44 ms and a low dominant frequency of 103 ± 31 Hz. Video recordings show that the camouflage grouper produces the 'booms' to initialize spawner ascent and to promote synchronous gamete release into the water column.5. The study highlights for the first time that PAM can be used to identify the previously unknown sound of a fish species. Moreover, we can use it to understand the phenology of some biological activities for improving the resolution of fish biodiversity assessments.

Local sonic activity reveals potential partitioning in a coral reef fish community

“…The latter two sound types were both series of pulses and were only differentiated by their dominant frequencies. The low frequency booming sound (Type 5) produced in series or in single ways matches the common characteristics of Serranidae sounds (Bertucci et al 2015;Jublier et al 2020), also very common in Polynesian reefs (Siu et al 2017). Type 6, like sound types 7-11, could not be attributed to a potential producer and further investigations are needed.…”

“…Temporal partitioning may therefore happen at larger time scales. Recently,Jublier et al (2020) presented the phenological patterns of six types of sounds at different temporal scales, from hourly, to daily, to lunar cycles occurring from 04-Jun-2017 to 12-Jun-2017, and from 06-Jul-2017 to 12-Jul-2017 during the reproduction aggregation of several species of coral reef fishes in the atoll of Fakarava (French Polynesia). Similarly, investigations over longer periods of time revealed seasonal partitioning between seven different fish choruses lasting from days to weeks.…”

Effects of COVID-19 pandemic restrictions on coral reef fishes at eco-tourism sites in Bora-Bora, French Polynesia

“…Alternative solutions such as the use of re-breathers, baited remote underwater video, or passive acoustic monitoring could be used in some instances to address this issue. In particular, acoustic monitoring (i.e., ‘indirect’ and non-invasive technique not subject to diver biases) is a promising pathway to rapidly obtain indicators of marine biodiversity allowing for less expensive, long-term and large scale monitoring with reduced human resources (e.g., Huetz and Aubin, 2002; Luczkovich et al, 2008; Bertucci et al, 2015 , 2020 ; Jubiler et al, 2020 ).While it is clear that tourism has an effect on the ecology of coastal environments (e.g., Hawkins and Roberts, 1992 ; Hawkins et al, 1999 ; Tratalos and Austin, 2001 ; Siriwong et al, 2018 ), this effect is often difficult to isolate due to the constant presence of human activity ( Bessa et al, 2017 ). Based on our findings, it appears that fish assemblages are altered as a result of tourism activities, and the COVID-19 pandemic provided an opportunity to collect data to this effect.…”

How many fish could be vocal? An estimation from a coral reef (Moorea Island)

“…Additional data are obviously needed to identify and validate calling species identity within these families and in others. At the current state of art, we know that there are more calling species than those currently identified, because most of the sounds recorded in the wild using passive acoustics have not yet been attributed to a species (JuBlier et al 2019;Bertucci et al 2020).…”