The sound of recovery: Coral reef restoration success is detectable in the soundscape

Abstract

1. Pantropical degradation of coral reefs is prompting considerable investment in their active restoration. However, current measures of restoration success are based largely on coral cover, which does not fully reflect ecosystem function or reef health.2. Soundscapes are an important aspect of reef health; loud and diverse soundscapes guide the recruitment of reef organisms, but this process is compromised when degradation denudes soundscapes. As such, acoustic recovery is a functionally important component of ecosystem recovery.3. Here, we use acoustic recordings taken at one of the world's largest coral reef restoration projects to test whether successful restoration of benthic and fish communities is accompanied by a restored soundscape. We analyse recordings taken simultaneously on healthy, degraded (extensive historic blast fishing) and restored reefs (restoration carried out for 1-3 years on previously degraded reefs). We compare soundscapes using manual counts of biotic sounds (phonic richness), and two commonly used computational analyses (acoustic complexity index [ACI] and sound-pressure level [SPL]).4. Healthy and restored reef soundscapes exhibited a similar diversity of biotic sounds (phonic richness), which was significantly higher than degraded reef soundscapes. This pattern was replicated in some automated analyses but not others; the ACI exhibited the same qualitative result as phonic richness in a lowfrequency, but not a high-frequency bandwidth, and there was no significant difference between SPL values in either frequency bandwidth. Furthermore, the low-frequency ACI and phonic richness scores were only weakly correlatedThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Sounds of a changing sea: Temperature drives acoustic output by dominant biological sound-producers in shallow water habitats

“…Thus, further investigation is needed to understand the relative importance of physical drivers on soundscape variation in snapping-shrimp dominated seas. Interacting direct and indirect effects of climate changes and snapping shrimp habitat degradation (e.g., coral bleaching, sponge host die-off) on soundscape variation should also be considered (Butler et al, 2016;Butler et al, 2017), particularly since snapping sounds strongly influence commonly used passive acoustic monitoring metrics of habitat health (Bohnenstiehl et al, 2018;Elise et al, 2019) and have been suggested as indicators of "healthy" soundscapes or habitat restoration success (Butler et al, 2021;Lamont et al, 2022).…”

“…Substantial changes in natural soundscapes have occurred due to increases in human use (Slabbekoorn et al, 2010;Butler et al, 2016;Buxton et al, 2017;Duarte et al, 2021), and a recent body of research has focused on anthropogenic noise and its detrimental impacts on organism physiology and behavior (e.g., Luczkovich and Sprague, 2008;de Soto et al, 2013;Hawkins and Popper, 2017;Jones et al, 2020). Increasing attention is also being given to soundscape measurement and analysis as an approach to monitor the impacts of human disturbance and climate change on biodiversity (Gage and Axel, 2014;Krause and Farina, 2016;Lamont et al, 2022). Far less is known about climate-driven changes to the soundscape and the biological drivers of those potential alterations, particularly for acoustically-rich ocean habitats.…”

Oyster larvae swim along gradients of sound

“…These ‘muted‐scapes’ carry less navigational information to dispersing organisms (Williams et al, 2021) in search for adult habitat. Hence, coastal restoration efforts that seek to restore habitat‐forming species and their ecosystem functions, which in turn revive these soundscapes (Lamont et al, 2021), may have low capacity for restoration where recruitment is limited. The most soniferous producers of biological noise in marine habitats are snapping shrimp (Johnson et al, 1947).…”

State of Play in Marine Soundscape Assessments

“…It is crucial that marine soundscape studies continue to be developed and pursued, in order to establish baselines for healthy ecosystems and/or document recovery following management actions (Lamont et al, 2021). With the rapid innovation of technology, especially data storage and declining cost of equipment, marine soundscape research is rapidly increasing.…”