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The sound of Gorgonian forests
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The aim of the study is to propose a non-invasive high-resolution proxy based on passive acoustics, to assess the health status of gorgonian forests and monitor their biodiversity and changes in response to human impacts and climate change to support managers in their conservation efforts of critical Mediterranean habitats. The project relies on a consortium of ecoacousticians, gorgonian ecologists, and environmental managers.
[/vc_column_text][vc_text_separator title=””][/vc_column][/vc_row][vc_row][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5417″ img_size=”full” alignment=”center” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][vc_column width=”2/3″][vc_custom_heading text=”Objectives & Ambition” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]Our ambition is to establish acoustic proxies of the health status of threatened gorgonian forests and develop a non-invasive monitoring strategy that can be implemented at large geographical scales to support government agencies. To achieve this goal, we build an interdisciplinary consortium composed of benthic ecologists, eco-acousticians and MPA managers to develop an innovative and easy-to-apply acoustic-based monitoring method. Thanks to expertise of the project manager in applied eco-acoustics, LECOB’s expertise in gorgonian ecology and a long-lasting cooperation with MPA managers, this ambition is not only feasible but can have wide-ranging conservation implications.
Modern conservation science underlines the urgent need and importance to define new metrics to measure habitat functionality rather than species. We propose to establish an innovative metric of the biodiversity and function of gorgonian forests based on the sounds emitted by the sheltered species. Our approach relies on the association of the habitat’s acoustic footprint, i.e. the diversity and abundance of invertebrate and fish sounds emanating from gorgonian forests and the forest’s demographic structure (e.g., diversity, density of gorgonians). This will allow to establish a new conservation unit and assess the health status of this emblematic Mediterranean habitat.
This study will increase our knowledge on gorgonian biodiversity and the response of gorgonians to human/climatic impacts. It also aims at setting-up a replicable, standardized passive acoustic protocol applicable at large scales within networks of MPAs to monitor the effects of global changes on threatened key habitats such as gorgonians forests, assessing their conservation status and guide policy instruments.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_custom_heading text=”Context” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]Gorgonian forests are biodiversity hotspots composed of long-lived engineering species, which play a crucial role for coastal habitats and contribute to ecosystem services. In the Mediterranean Sea, gorgonians not only increase habitat biodiversity but also play a role in the blue carbon budget as the two main coastal species sequestrate 1.5 gCm-2 year-1. They are also vulnerable to environmental stressors and their destruction leads to loss of biodiversity and ecosystem functioning. Water temperature increase caused large declines of gorgonian forests (up to 60% of biomass loss) and its associated biodiversity across the Mediterranean Sea via mass mortality events, disease outbreaks and spreading of invasive species, with long-term consequences on ecosystem functioning. The IUCN highlighted “the need in determining gorgonian population trends, health status, and assess the effectiveness of conservation actions under future climate change scenarios”. Despite this, no large-scale monitoring programs exist. Monitoring changes in their functionality is critical for biodiversity and habitat conservation and in line with the objective of the modern management plans focusing on ecosystem function rather than species. The ecological function of gorgonians depends on the density and structure of the forest. Assessing the minimum number of gorgonians necessary to form a forest allows to identify a minimum conservation unit and set a target for management and conservation.[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5393″ img_size=”full” alignment=”center” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5411″ img_size=”full” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][vc_column width=”2/3″][vc_custom_heading text=”Passive Acoustic Monitoring & habitat conservation” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]For the conservation of key habitats, we need high-resolution monitoring methods that can capture ecosystem health dynamics with low human effort and that can be extended over vast geographical areas and over the long term. Passive Acoustic Monitoring (PAM) can be applied at large spatial and temporal scales, night and day and at high temporal resolution, allowing to follow biodiversity trends, identify environmental stressors and appraise recovery of animal communities and habitats via the sounds they emit. PAM is a holistic ecosystem-based method, non-invasive and applicable to inaccessible habitats (great depths), and is also useful to record abiotic factors such as wind and rain, characterize noise pollution and assess its impact on habitats. The project manager has long-term experience in acoustically studying critical marine habitats (seagrasses, coralligenous and rocky reefs), the effects of protection measures, and is involved in a unique large-scale sound surveillance network developed by the Chorus Institute and the he Water Agency RMC, the “reseau CALME”. PAM therefore has a great potential to be implemented in ocean-monitoring networks, particularly in the face of climate change.
Moreover, PAM is a standardized and easily replicable method with low commitment of human resources. No similar approaches are available today, although necessary for conservation as they allow to monitor species, habitats, anthropogenic impact simultaneously and are suitable for implementation in networks to concretely help managers to evaluate and adjust conservation measures for the protection of biodiversity in the face of global change.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_custom_heading text=”Eco-acoustics for Gorgonians ” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]Ecoacoustics is a growing branch with promising possibilities of practical applications for marine ecosystem conservation. The innovative aspect of our project is the use of ecoacoustics for the study of biodiversity hotspots, such as gorgonian forests. The quantification of the diversity, abundance and activity of animals living in dense habitats such as seagrass meadows or gorgonian forests can be technically difficult and time consuming, especially in deep environments. Acoustics can provide information on the invisible species and their activities 24h a day and on the long term and represents a suitable and efficient method to apprise hidden biodiversity. In fact, invertebrates, fishes and marine mammals emit sounds unintentionally when moving or feeding for instance or voluntarily, to communicate, defend territories, forage, during reproduction, etc. Animal sounds can therefore reflect behaviours and life strategies and they also provide information about vital functions within a habitat, which are the focus of modern conservation science. The diversity and abundance of sounds emanating from an environment forms an acoustic footprint which reflects the diversity and activity of animal communities (invertebrates & fish) and has been shown to be habitat-specific, linked to taxonomic diversity and a relevant and non-invasive proxy of habitat quality.[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5407″ img_size=”full” alignment=”center” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5425″ img_size=”full” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][vc_column width=”2/3″][vc_custom_heading text=”Approach” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]Using a published acoustic mapping method, we will associate acoustic richness and diversity to the structure (density and size distribution) of gorgonian forests in different health conditions. 3D acoustic recordings of biological sounds have proven successful in studying and quantifying fauna and monitoring restoration in seagrass meadows, coralligenous outcrops and artificial reefs. The combination of 3D acoustic recordings and demographic studies based on classical visual identification and counting methods will help define a new conservation unit for gorgonian forests and develop a unique proxy of their ecological function and health status descriptor that allows to assess the response of the habitat to temperature variations via its acoustic footiprint.
In coordination between L. Di Iorio (ecoacoustician, University of Perpignan, associated researcher of the Chorus Institute) and L. Bramanti (coral ecology, CNRS LECOB), data will be collected in 3 MPAs with gorgonian populations in different health conditions:
- 5 Terre MPA (Italy), with the “urban forest”: typical gorgonian forest of the Western Mediterranean in anthropized, noisy areas
- National Park of Port-Cros (F), founded in 1963, or the Natural Reserve of Cerbère-Banyuls (F), founded in 1974, with the “virgin forest”: a reference for the functional role of gorgonian forests
- Tavolara MPA (Italy), with the “ghost forest”: a population severely damaged by a recent mass mortality event that left almost only gorgonian skeletons.
The campaigns will be conducted during the summer. At each site, rims with different gorgonian densities will be selected at similar depth gradients. On each rim, diversity, richness, density and size structures of gorgonian forests will be measured by SCUBA diving over an area of about 3×3 meters. At the same time, the sounds of the forest, representing the associated biodiversity, will be recorded and quantified within the same area and spatial resolution using a compact hydrophone network that allows to accurately (20cm) locate each sound and measure sound diversity, abundance and acoustic energy. This technique, developed by Chorus, is regularly applied for environmental monitoring. The association of demographic and acoustic data will allow the characterization of the gorgonian forests’ acoustic footprint along a biodiversity and temperature gradient and the establishment of acoustic indicators of the functionality, health status of this emblematic habitat and it’s responses to temperature variations.
The outcomes will will help MPA managers to implement survey plans based on a holistic approach capable of capturing ecosystem dynamics and monitor environmental changes and the efficiency of management actions. The project relies on the multi-competence and institutional consortium and will promote cross-boundary and interdisciplinary collaboration within the scope of environmental protection.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_custom_heading text=”Outputs & expected impacts” google_fonts=”font_family:Montserrat%3Aregular%2C700|font_style:400%20regular%3A400%3Anormal”][vc_column_text]At short-term, we will shed light on the acoustic biodiversity associated to gorgonian forests and assess variations in their functionality in response to environmental pressures. The MPAs involved in the project will have acoustic maps and quantification of the biodiversity associated to their gorgonian forests. They will also participate in the development of acoustic descriptors suitable for ecosystem monitoring.
At middle-term, the definition of a new conservation unit for gorgonian forests may become a priority conservation target and a valuable instrument for MPAs management plans. An increase of gorgonian forests functionality will have positive effects on the communities and ecosystem in which they dwell. Moreover, MPAs could become benchmarks for the implementation of the here proposed non-intrusive ecoacoustic solutions to monitor the health status of key protected habitats and its variations with increasing disturbances, contribute to the Marine Strategy Framework Directive and help define conservation actions.
At long-term, the development of ecoacoustic methodologies and proxies for environmental monitoring will give a new set of holistic standardized means applicable at large scales. It will support managers in real-time global monitoring and in following the efficiency of protection measures. Furthermore, it may highlight the need of anthropogenic noise regulation in MPAs that already showed positive results in terrestrial National Parks but is still not implemented in the marine realm, where noise propagates 5 times faster than in air with wide-ranging impacts.[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_row_inner][vc_column_inner][vc_single_image image=”5429″ img_size=”full” style=”vc_box_rounded”][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image=”5433″ img_size=”large” alignment=”center”][/vc_column][/vc_row][vc_row][/vc_row]