Acoustic Complexity Index to assess benthic biodiversity of a partially protected area in the southwest of the UK

Abstract

The soundscape of the marine environment is a relatively understudied area of ecology that has the potential to provide large amounts of information on biodiversity, reproductive behaviour, habitat selection, spawning and predator-prey interactions. Biodiversity is often visually assessed 2 | P a g e and used as a proxy for ecosystem health. Visual assessment using divers or remote video methods can be expensive, and limited to times of good weather and water visibility. Previous studies have concluded that acoustic measures, such as the Acoustic Complexity Index (ACI), correlate with visual biodiversity estimates and offer an alternative to assess ecosystem health.Here, the ACI measured over 5 years in a Marine Protected Area (MPA) in the UK, Lyme Bay, was analysed alongside another monitoring method, Baited Remote Underwater Video Systems (BRUVs). Two treatments were sampled annually in the summer from 2014 until 2018 with sites inside the MPA, as well as Open Control sites outside of the MPA.Year by year correlations, which have been used elsewhere to test ACI, showed significant correlations with Number of Species and ACI. However, the sign of these correlations changed almost yearly, showing that more in-depth analyses are needed. Multivariate analysis of the benthic assemblage composition (from BRUVs) was carried out byPermutational Multivariate Analysis of Variance (PERMANOVA) using Distance Matrices.Although not consistently correlating with univariate measures, the ACI was significantly interacting with the changing benthic assemblage composition, as it changed over time and protection (Inside vs Outside the MPA).ACI showed potential to allude to shifting benthic communities, yet with no consistency when used alongside univariate measures of diversity. Although it is not without its own disadvantages, and thus should be developed further before implementation, the ACI could potentially reflect more complex changes to the benthos than simply the overall diversity.

Rapid coral reef assessment using 3D modelling and acoustics: acoustic indices correlate to fish abundance, diversity and environmental indicators in West Papua, Indonesia

“…Technologies can increase the scope of data collection in marine environments ( Obura et al, 2019 ), but often require specialist training and equipment. Two promising visual and audio approaches amenable to rapid and community-level data collection for coral reef monitoring include (i) habitat metrics, such as rugosity, extracted from 3D models generated by photogrammetry (Structure from Motion SfM) ( Young et al, 2017 ; Burns et al, 2019 ) and (ii) use of acoustic indices as a proxy for vertebrate and invertebrate diversity ( Bertucci et al, 2016 ; Bohnenstiehl et al, 2018 ; Bolgan et al, 2018 ; Obura et al, 2019 ; Elise et al, 2019b ; Davies et al, 2020 ).…”

A decade implementing ecosystem approach to fisheries management improves diversity of taxa and traits within a marine protected area in the UK

“…Replicate deployments were spaced ~100 m apart to depths ranging from 15 to 32 m, before being recovered after 45 min. Videos from BRUVs were assessed in situ to ensure that the camera had landed and recorded a viable sample (Davies et al, 2020; Davies, Holmes, Rees, et al, 2021). Failed attempts were repeated to ensure that all samples were suitable.…”

“…Sessile and sedentary epifauna were monitored using a towed underwater video system (“towed flying array” henceforth), while mobile species were monitored with Baited Remote Underwater Video systems (BRUVs; Davies et al, 2020; Davies, Holmes, Rees, et al, 2021; Sheehan et al, 2010; Sheehan, Stevens, et al, 2013; Sheehan et al, 2016; Stevens et al, 2014). The combination of these data collection methods, which estimate the abundance of species ranging from sessile branching sponges to highly mobile elasmobranchs, allow the assessment of a large proportion of the benthic ecosystem.…”

Camera methods for the assessment of coastal biodiversity in low visibility environments

“…There are no depth or substrate limitations when using acoustic survey equipment allowing for large areas of Chapter 1: Challenges of assessing coastal environments: A review substrata to be mapped in a short space of time (Magorrian et al, 2009). Additionally, the use of acoustic measures such as the acoustic complexity index can be used to correlate with visual biodiversity estimates to offer an alternative to assess ecosystem health (Davies et al, 2020).…”

“…Unlike underwater camera surveys, acoustic methods are not restricted by poor water visibility (Davies et al, 2020) whether it's for marine mammal and fish detection or benthic habitat mapping (Dudzinski et al, 2011). However, research has suggested that acoustic detections of organisms are susceptible to acoustic backscatter in areas of extreme turbulence or turbid sediment-laden waters (Melvin & Cochrane, 2014).…”