@article {57931, title = {It{\textquoteright}s time to listen: there is much to be learned from the sounds of tropical ecosystems}, year = {2018}, abstract = {

Knowledge that can be gained from acoustic data collection in tropical ecosystems is low-hanging fruit. There is every reason to recordand with every day, there are fewer excuses not to do it. In recent years, the cost of acoustic recorders has decreased substantially(some can be purchased for under US$50, e.g., Hillet\  al.2018) and the technology needed to store and analyze acoustic data is contin-uously improving (e.g., Corrada Bravoet\  al.2017, Xieet\  al.2017). Soundscape recordings provide a permanent record of a site at agiven time and contain a wealth of invaluable and irreplaceable information. Although challenges remain, failure to collect acoustic datanow in tropical ecosystems would represent a failure to future generations of tropical researchers and the citizens that benefit fromecological research. In this commentary, we (1) argue for the need to increase acoustic monitoring in tropical systems; (2) describe thetypes of research questions and conservation issues that can be addressed with passive acoustic monitoring (PAM) using both short-and long-term data in terrestrial and freshwater habitats; and (3) present an initial plan for establishing a global repository of tropical recordings.

}, keywords = {conservation technology, ecoacoustics, passive acoustic monitoring, Soundscape}, doi = {10.1111/btp.12593}, url = {http://doi.wiley.com/10.1111/btp.12593}, author = {Jessica L. Deichmann and Acevedo-Charry, Orlando and Barclay, Leah and Burivalova, Zuzana and Campos-Cerqueira, Marconi and d{\textquoteright}Horta, Fernando and Game, Edward T. and Gottesman, Benjamin L. and Hart, Patrick J. and Kalan, Ammie K. and Linke, Simon and Nascimento, Leandro Do and Bryan C. Pijanowski and Staaterman, Erica and T. Mitchell Aide} } @article {57648, title = {Using acoustic metrics to characterize underwater acoustic biodiversity in the Southern Ocean}, year = {2019}, abstract = {

Acoustic metrics (AM) assist our interpretation of acoustic environments by aggregating a complex signal into a unique number. Numerous AM have been developed for terrestrial ecosystems, with applications ranging from rapid biodiversity assessments to characterizing habitat quality. However, there has been comparatively little research aimed at understanding how these metrics perform to characterize the acoustic features of marine habitats and their relation with ecosystem biodiversity. Our objectives were to 1) assess whether AM are able to capture the spectral and temporal differences between two distinct Antarctic marine acoustic environment types (i.e., pelagic vs. on-shelf), 2) evaluate the performance of a combination of AM compared to the signal full frequency spectrum to characterize marine mammals acoustic assemblages (i.e., species richness\–SR\–and species identity) and 3) estimate the contribution of SR to the local marine acoustic heterogeneity measured by single AM. We used 23 different AM to develop a supervised machine learning approach to discriminate between acoustic environments. AM performance was similar to the full spectrum, achieving correct classifications for SR levels of 58\% and 92\% for pelagic and on-shelf sites respectively and \> 88\% for species identities. Our analyses show that a combination of AM is a promising approach to characterize marine acoustic communities. It allows an intuitive ecological interpretation of passive acoustic data, which in the light of ongoing environmental changes, supports the holistic approach needed to detect and understand trends in species diversity, acoustic communities and underwater habitat quality.

}, keywords = {Acoustic metrics, Antarctic, community composition, marine acoustic environments, passive acoustic monitoring, species diversity}, doi = {10.1002/rse2.129}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/rse2.129}, author = {Roca, Irene T. and Van Opzeeland, Ilse}, editor = {Pettorelli, Nathalie and Quick, Nicola} } @article {57604, title = {Using acoustic metrics to characterize underwater acoustic biodiversity in the Southern Ocean}, year = {2019}, abstract = {

Acoustic metrics (AM) assist our interpretation of acoustic environments by aggregating a complex signal into a unique number. Numerous AM have been developed for terrestrial ecosystems, with applications ranging from rapid bio- diversity assessments to characterizing habitat quality. However, there has been comparatively little research aimed at understanding how these metrics perform to characterize the acoustic features of marine habitats and their relation with ecosystem biodiversity. Our objectives were to 1) assess whether AM are able to capture the spectral and temporal differences between two distinct Antarctic marine acoustic environment types (i.e., pelagic vs. on-shelf), 2) evaluate the performance of a combination of AM compared to the signal full frequency spectrum to characterize marine mammals acoustic assemblages (i.e., species richness\–SR\–and species identity) and 3) estimate the contribution of SR to the local marine acoustic heterogeneity measured by single AM. We used 23 differ- ent AM to develop a supervised machine learning approach to discriminate between acoustic environments. AM performance was similar to the full spec- trum, achieving correct classifications for SR levels of 58\% and 92\% for pelagic and on-shelf sites respectively and \> 88\% for species identities. Our analyses show that a combination of AM is a promising approach to characterize marine acoustic communities. It allows an intuitive ecological interpretation of passive acoustic data, which in the light of ongoing environmental changes, supports the holistic approach needed to detect and understand trends in species diver- sity, acoustic communities and underwater habitat quality.

}, keywords = {Acoustic metrics, Antarctic, community composition, marine acoustic environments, passive acoustic monitoring, species diversity}, doi = {10.1002/rse2.129}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/rse2.129}, author = {Roca, Irene T. and Van Opzeeland, Ilse}, editor = {Pettorelli, Nathalie and Quick, Nicola} } @article {57351, title = {An optimised passive acoustic sampling scheme to discriminate among coral reefs{\textquoteright} ecological states}, journal = {Ecological Indicators}, volume = {107}, year = {2019}, month = {Jan-12-2019}, pages = {105627}, abstract = {

In the present era of rapid global change, innovative monitoring methods can greatly enhance our ability to detect ecological disturbances and prioritise conservation areas in a timely and cost-effective manner. While Passive Acoustic Monitoring (PAM) has recently emerged as a promising tool for monitoring ecological states in marine environments, the specifics of how to apply this method remains poorly defined. In this study we examined how different combinations of sampling settings (frequency bandwidth, time of sampling (day/night), and sample duration) influenced the ability of two acoustic indices, the Sound Pressure Level (SPL) and the Acoustic Complexity Index (ACI), to discriminate different ecological states (ecostates) of coral reefs. We applied an iterative approach to select the most efficient and consistent combinations of sampling settings to use for these two acoustic indices, depending on the stability of their discriminating power across different time scales (successive days, moon phases, and seasons), and the minimum sampling effort required for reliable ecostate assessment. The ability of SPL and ACI to discriminate ecostate-specific soundscapes was more stable and required less sampling effort at nighttime. For indices calculated in the higher frequency band (\>2 kHz), very short recording times (\≤20 min divided into 5 s samples) were sufficient to discriminate ecostates, whereas longer recording times (\≥200 min divided into 5 min samples) were necessary when using indices calculated in the lower frequency bands (\<1 kHz). An optimised sampling scheme, i.e. the group of the five best combinations of settings to discern among coral reef ecostates, was determined at Reunion Island, Indian Ocean, then tested at New Caledonia, Pacific Ocean. Here, the classifications obtained through visual surveys and with the optimised acoustic sampling scheme were congruent. The concordance of our results with visual fish counts confirms the potential of ecoacoustics to rapidly and reliably characterise coral reefs\’ ecostate, allowing managers to prioritise conservation areas among numerous sites, and detect ecological changes over time. Our study provides clear guidelines for monitoring soundscapes by means of the ecoacoustic indices most widely used in the marine realm.

}, keywords = {Coral reefs, Ecoacoustic indices, Ecological state (ecostate), Marine habitats, passive acoustic monitoring, Sampling scheme}, issn = {1470160X}, doi = {10.1016/j.ecolind.2019.105627}, author = {Elise, Simon and Bailly, Arthur and Urbina-Barreto, Isabel and Mou-Tham, G{\'e}rard and Chiroleu, Fr{\'e}d{\'e}ric and Vigliola, Laurent and Robbins, William D. and Bruggemann, J. Henrich} } @article {57345, title = {Assessing key ecosystem functions through soundscapes: A new perspective from coral reefs}, journal = {Ecological Indicators}, volume = {107}, year = {2019}, month = {Jan-12-2019}, pages = {105623}, abstract = {

The functioning of tropical coral reefs is imperilled by climate change, overfishing, and decreasing water quality. Maintaining their capacity to provide goods and services will critically depend on our ability to monitor their functioning at appropriate spatial and temporal scales. Given the constraints of traditional methods to respond to those needs, the potential of complementary tools such as Passive Acoustic Monitoring (PAM) is emerging. Coral reef soundscapes (i.e. ambient sound) encompass sounds produced by numerous organisms. Soundscape characteristics quantified by ecoacoustic indices have been found to reflect general ecosystem properties, such as diversity and abundance of fishes, and coral cover. The present study tested, on the virtually pristine coral reefs around Europa Island, South-West Indian Ocean, the capacity of acoustic indices to assess key ecosystem functions. Soundscapes were recorded during 2 h, and ecosystem functions were evaluated using video footage of the fish assemblages and underwater photogrammetry of the benthic landscapes. We found significant and strong correlations between six ecoacoustic indices and six key ecosystem functions, including habitat features and fish assemblage characteristics. The six ecoacoustic indices were representative of several combinations of frequency, amplitude and time analysis domains, highlighting the diversity of the functional information conveyed by soundscapes. Our findings reveal that a 2 h daytime recording on a coral reef could provide sufficient acoustic information to characterise major ecosystem functions of a site. This should facilitate the detection of functional disturbances at temporal and spatial scales adapted to the rapidity of upcoming climate changes. Our results also highlight the potential of ecoacoustics to bring novel and relevant insights in the functioning of ecosystems.

}, keywords = {conservation, Coral reefs, Ecoacoustic indices, Key ecosystem functions, passive acoustic monitoring, Soundscape}, issn = {1470160X}, doi = {10.1016/j.ecolind.2019.105623}, author = {Elise, Simon and Urbina-Barreto, Isabel and Pinel, Romain and Mahamadaly, Vincent and Bureau, Sophie and Penin, Lucie and Adjeroud, Mehdi and Kulbicki, Michel and Bruggemann, J. Henrich} } @article {52855, title = {Acoustic indices as rapid indicators of avian diversity in different land-use types in an Indian biodiversity hotspotAbstract}, journal = {Journal of Ecoacoustics}, volume = {2}, year = {2018}, month = {Jan-18-2018}, abstract = {

Passive acoustic monitoring is a potentially valuable tool in biodiversity hotspots, where surveying can occur at large scales across land conversion types. However, in order to extract meaningful biological information from resulting enormous acoustic datasets, rapid analytical techniques are required. Here we tested the ability of a suite of acoustic indices to predict avian bioacoustic activity in recordings collected from the Western Ghats, a biodiversity hotspot in southwestern India. Recordings were collected at 28 sites in a range of land-use types, from tea, coffee, and cardamom plantations to remnant forest stands. Using 36 acoustic indices we developed random forest models to predict the richness, diversity, and total number of avian vocalizations observed in recordings. We found limited evidence that acoustic indices predict the richness and total number of avian species vocalizations in recordings (R2 \< 0.51). However, acoustic indices predicted the diversity of avian species vocalizations with high accuracy (R2 = 0.64, mean squared error = 0.17). Index models predicted low and high diversity best, with the highest residuals for medium diversity values and when continuous biological sounds were present (e.g., insect sounds \>8\ sec). The acoustic complexity index and roughness index were the most important for predicting avian vocal diversity. Avian species richness was generally higher among shade-grown crops than in the open tea plantation. Our results suggest that models incorporating acoustic indices can accurately predict low and high avian species diversity from acoustic recordings. Thus, ecoacoustics could be an important contributor to biodiversity monitoring across landscapes like the Western Ghats, which are a complex mosaic of different land-use types and face continued changes in the future.

}, keywords = {diversity, landscape, passive acoustic monitoring, shade-grown crop, species richness, Western Ghats}, doi = {10.22261/JEA10.22261/JEA.GWPZVD}, url = {https://www.veruscript.com/journals/journal-of-ecoacoustics/acoustic-diversity-in-an-indian-hotspot/}, author = {Agnihotri, Samira and Robin, V. V. and Goel, Anurag and Rohini Balakrishnan} }