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

Abstract

How vocal organisms share acoustic space has primarily received attention in terrestrial environments. Comparable studies in marine environments, however, remain rare. By recording sounds on a coral reef in French Polynesia for 48 h and 24 h, this study provides first insights on how different sound types are distributed within the acoustic space and may create acoustic niches optimizing acoustic communication within a highly diverse community containing numerous soniferous fish species. Day-time was dominated by two to six sound types, while recordings performed at night revealed a more diverse vocal community made of up to nineteen sound types. Calling activity was distributed over time allowing each sound type to dominate the soundscape sequentially. Additionally, differences in the acoustic features of sounds occurring during the same period were observed. Such partitioning in time and acoustic spaces would reduce potential overlaps of sounds produced by vocal species living in sympatry in coral reefs.

From the Reef to the Ocean: Revealing the Acoustic Range of the Biophony of a Coral Reef (Moorea Island, French Polynesia)

“…Moreover, a peak in this higher frequency band was observed at both dawn and dusk. Similar diel patterns have been previously described from Polynesian [7,85] and non-Polynesian coral reefs [9,86].…”

“…Typical soundscapes of New Zealand rocky reefs have peak intensities between 1 and 1.9 kHz [91]. These peaks are generally absent in coral reefs soundscapes [7,9,85,86] where they usually occupy frequencies between 3 and 6 kHz. As these peaks in temperate water are within the audible range of several of species of fish, cetaceans and invertebrates, they likely affect detection distances.…”

“…Fish [3] and invertebrate [4] sounds constitute the most persistent part and the majority of coastal biophonies. Coral reefs are considered to be hotspots of biodiversity [5] and acoustic hotspots [6,7]. In these environments, snapping shrimps tend to dominate reef soundscapes at frequencies above 1 kHz [8], while a band attributed to damselfish is found around 400 Hz [9].…”

Community Bioacoustics: Studying Acoustic Community Structure for Ecological and Conservation Insights

“…Divergence of signal properties reduces masking, enables segregation of competing sound streams (MacDougall-Shackleton et al, 1998;Krishnan, 2019b), and thus reinforces species recognition and premating isolation between close relatives (Nelson, 1988(Nelson, , 1989Grant and Grant, 1996;Qvarnström et al, 2006). In diverse animals [crickets: (Schmidt et al, 2013), cicadas: (Shieh et al, 2015), aquatic insects: (Gottesman et al, 2020), fish: (Ruppé et al, 2015;Bertucci et al, 2020), anurans: (Drewry and Rand, 1983;Duellman and Pyles, 1983;Narins, 1995;Chek et al, 2003), birds: (Kirschel et al, 2009b(Kirschel et al, , 2020Krishnan and Tamma, 2016;Chitnis et al, 2020), bats: (Heller and von Helversen, 1989;Kingston et al, 2000;Luo et al, 2019), primates: (Braune et al, 2008)], closely related sympatric species exhibit divergent signals, partitioning the acoustic resource to minimize acoustic competition. Each species is therefore predicted to occupy a unique region or "niche" in the acoustic resource, a hypothesis extrapolated from ecological niche theory (Hutchinson, 1957;Holt, 2009).…”

“…Temporal partitioning may involve fine-scale adjustments to signal timing and repetition rate, resulting in interdigitation of the signals of different individuals [birds: (Cody and Brown, 1969;Ficken et al, 1974;Fleischer et al, 1985;Popp et al, 1985;Brumm, 2006)]. Alternatively, both terrestrial and aquatic species may simply signal at different times of the day from each other, or even in different seasons [birds: (Luther, 2008;Krishnan, 2019a), bats: (Adams and Thibault, 2006;Mancina et al, 2012), fish: (Ruppé et al, 2015;Bertucci et al, 2020), marine mammals: (De Vreese et al, 2018)]. Further research is required to understand if diel-scale temporal partitioning results indirectly from ecological separation in foraging time, or by adjustments to the presence of competing signalers.…”