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        <title>Frontiers in Remote Sensing | Acoustic Remote Sensing section | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/remote-sensing/sections/acoustic-remote-sensing</link>
        <description>RSS Feed for Acoustic Remote Sensing section in the Frontiers in Remote Sensing journal | New and Recent Articles</description>
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        <pubDate>2026-05-13T15:28:02.41+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2026.1804992</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2026.1804992</link>
        <title><![CDATA[Editorial: Multibeam echosounder backscatter: advances and applications]]></title>
        <pubdate>2026-03-05T00:00:00Z</pubdate>
        <category>Editorial</category>
        <author>Craig J. Brown</author><author>Marc Roche</author><author>Vanessa Lucieer</author><author>Alexandre C. G. Schimel</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2026.1801687</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2026.1801687</link>
        <title><![CDATA[Editorial: Detection and characterization of unidentified underwater biological sounds, their spatiotemporal patterns, and possible sources]]></title>
        <pubdate>2026-03-03T00:00:00Z</pubdate>
        <category>Editorial</category>
        <author>Lucia Di Iorio</author><author>Audrey Looby</author><author>Francis Juanes</author><author>Tzu-Hao Lin</author><author>Zhongchang Song</author><author>Jenni Stanley</author><author>Miles J. G. Parsons</author>
        <description><![CDATA[Graphical AbstractInfographic illustrating research themes in unidentified underwater biological sounds, featuring animal silhouettes surrounded by arrows pointing to images representing identifying, finding, understanding, and using sounds, along with maps, graphs, and labeled research categories and references.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1572674</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1572674</link>
        <title><![CDATA[Estimating biomass volumes on aquaculture dropper lines using multibeam water column data]]></title>
        <pubdate>2026-02-09T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Thomas Vandorpe</author><author>Samira Lashkari</author><author>Kobus Langedock</author><author>Alexia Semeraro</author><author>Gert Van Hoey</author><author>Tomas Sterckx</author><author>Ine Moulaert</author>
        <description><![CDATA[Assessing the biomass on longline setups based on acoustic data hold significant potential for improving the efficiency and accuracy of monitoring and management of aquaculture setups. Traditional assessment methods, such as manual sampling and visual inspections, are not only labor-intensive and time-consuming but are also subject to variability, often leading to under- or overestimations. Acoustic data, particularly multibeam water column (MBWC) data, provide a non-invasive alternative that can significantly enhance biomass estimation. Within this paper, we demonstrate that 2D and 3D visualizations based on MBWC data can effectively display aquaculture longline structures. To facilitate processing of MBWC data, we have developed scripts that allow to filter and cluster the data into individual dropper lines, enabling an estimation of the biomass volume on each dropper line individually. Our approach offers a scalable and cost-effective solution for aquaculture monitoring, reducing the reliance on destructive sampling and improving decision-making capabilities. Future improvements, such as enhanced data density, refined filtering techniques and automated acquisition workflows, will further increase the accuracy and usability of this method. Ultimately, this research provides aquaculture managers with an innovative tool for rapid volume assessments, contributing to the optimization of sustainable aquaculture practices.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2026.1672398</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2026.1672398</link>
        <title><![CDATA[From detection to complexity: AI boulder mapping enables structural analysis of Baltic Sea reefs]]></title>
        <pubdate>2026-01-26T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Aïcha Naumann</author><author>Peter Feldens</author><author>Michael L. Zettler</author><author>Svenja Papenmeier</author>
        <description><![CDATA[Advances in AI-based boulder detection using hydroacoustic data enable detailed characterization of geogenic reefs. As AI-based detection approaches the level of accuracy of human interpretation in small-scale test areas, it opens up the opportunity to efficiently analyze and characterize larger regions. Geogenic hard substrates are a key habitat for diverse benthic communities that provide crucial ecosystem services. Current classification schemes for boulder fields in the German Baltic Sea, using three categories (0 boulders, 1-5 boulders, and >5 boulders) inadequately capture habitat complexity, thus limiting our understanding of these critical geogenic reefs. Convolutional neural networks were used to detect individual boulders on side scan sonar backscatter mosaics with 25 cm resolution across four study sites, covering an area of 306 km2 in the German Baltic Sea. Region-specific AI models detected about 6.7 times more boulders than previous automated methods. A maximum of 550 boulders per 50 × 50 m grid cell were detected. A novel metric, the Boulder Field Complexity Index (BFCI), was developed to describe the complexity of boulder fields. The BFCI integrates boulder count with the transition of sharpness and the spatial distribution of individual boulders. Compared to conventional approaches, the BFCI enables the characterization of boulder field complexity on a continuous scale and reveals significant complexity differences between study sites. The coastal and shallow study site Plantagenet Ground demonstrates the highest level of complexity, whereas the offshore and deepest study site, Western Rönnebank, exhibits the lowest. The abundance of boulders is negatively correlated with water depth, with the highest densities occurring in shallow waters. The spatial variability in BFCI values reflects the heterogeneous nature of glacial till deposits and differential erosion processes that have shaped boulder field distribution. This approach provides the foundation for linking habitat heterogeneity to benthic community patterns and ecosystem functioning.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1522641</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1522641</link>
        <title><![CDATA[A universal symphony: coral reef fish calls exhibit consistent acoustic characteristics across different bioregions]]></title>
        <pubdate>2025-12-18T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Lucille Chapuis</author><author>Tzu-Hao Lin</author><author>Ben Williams</author><author>Timothy A. C. Lamont</author><author>Rucha Karkarey</author><author>Gabriela G. Nava-Martínez</author><author>Aya Maryam Rahil Naseem</author><author>Andrew N. Radford</author><author>Stephen D. Simpson</author>
        <description><![CDATA[Coral reefs host diverse fish communities, many of which produce sounds. Passive acoustic monitoring (PAM) has become an essential tool for studying these ecosystems, yet the variability in fish calls across regions remains poorly understood. In this study, we analysed 144 h of underwater recordings collected from six coral reef locations around the world, automatically detecting more than 120,000 fish calls. Using Geometric Morphometrics Methods (GMM), Principal Component Analysis (PCA) and Uniform Manifold Approximation and Projection (UMAP), we examined both the three-dimensional shape and spectro-temporal properties of these sounds. The GMM analysis revealed that fish calls showed remarkable acoustic similarity across geographical areas, with the first two principal components explaining 33% of the total variance. Typical fish calls consisted of short (<1 s), low-frequency sounds (∼500 Hz). The UMAP embedding, based on five key acoustic parameters, revealed a largely homogeneous distribution of fish calls across geographical locations. These results suggest that coral reef fish calls exhibit a level of global consistency, potentially reflecting the conserved structure of fish communities across different biogeographic realms. This study emphasises the potential of unknown fish call analyses as a non-invasive tool to explore fish diversity and assemblages, with future work required to extend these findings to other marine ecosystems and integrate automated species identification systems.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1703531</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1703531</link>
        <title><![CDATA[Correction: Acoustic backscatter processing in GLOBE: an open-source software for echo sounder data analysis]]></title>
        <pubdate>2025-10-07T00:00:00Z</pubdate>
        <category>Correction</category>
        <author>C. Poncelet</author><author>A. Saunier</author><author>A. Gaillot</author><author>G. Billant</author><author>L. Berger</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1650603</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1650603</link>
        <title><![CDATA[Assessing the importance of acoustic backscatter and bottom trawling impact as predictor variables for mapping deep sea coral reefs]]></title>
        <pubdate>2025-09-29T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Christopher Berry</author><author>Vanessa Lucieer</author><author>Joanne M. Whittaker</author><author>Franziska Althaus</author><author>Alan Williams</author>
        <description><![CDATA[Seamounts host some of the most biodiverse and vulnerable deep-sea ecosystems, as epitomised by the elevated diversity and biomass of fauna associated with extensive reefs of the frame-work forming coral Solenosmilia variabilis. In places, these vulnerable marine ecosystems (VMEs) have been substantially impacted by commercial bottom trawl fishing and face increasing threats from climate variability. Understanding both the current and historical distribution of coral reefs enables naturalness and recovery to be considered in conservation planning. Our study on the Tasmanian seamounts, an area characterised by extensive deep-sea coral reefs and historical trawling impacts, employed fine-scale Species Distribution Modelling (SDM) using acoustically derived bathymetry and backscatter data resolved to 15 m resolution to capture fine-scale habitat heterogeneity. We used a two-model methodology to predict VME habitat distributions before and after trawling impacts across a broad region (>480 km2) containing multiple seamounts with peak depths ranging from 720–2,073 m and varied substrates, as indicated by a spectrum backscatter intensity values. Bathymetry, relative slope position, backscatter and trawling history were most influential among a suite of predictor variables. Comparison of before and after models showed a reduction in both total area and patch sizes of coral habitat consistent with areas classified as historically impacted by trawling. The reduction in extent of coral VME area was dependent on the probability threshold of habitat suitability used in the model, decreasing by 20.44%–26.07% following trawling across a range of thresholds from 0.5–0.85. Our study highlights the benefits to future spatially based biodiversity management initiatives that will stem from using high-resolution bathymetry and backscatter data, and information on anthropogenic impacts, in SDM predictions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1619218</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1619218</link>
        <title><![CDATA[A simplified semi-empirical model for multifrequency seafloor backscattering angular response (ESAB)]]></title>
        <pubdate>2025-09-26T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Luciano Fonseca</author><author>Xavier Lurton</author><author>Ridha Fezzani</author><author>Marc Roche</author>
        <description><![CDATA[A new approach to seafloor acoustic backscatter prediction and inversion is presented here and applied to an experimental dataset. Based on a frequency-dependent semi-empirical geometrical-physical description, the Extended Seabed Acoustic Backscatter (ESAB) model addresses the seabed backscatter angular response over a wide frequency range, a key issue today in seafloor-mapping operations using multibeam echosounders. Starting from classical backscatter models, ESAB considers three main physical parameters corresponding to acoustical properties prevalent in seabed scattering phenomena: acoustical impedance, roughness facet-slope variance and sediment-volume scattering index. Classical theories are applied to describe the main backscatter components, for interface roughness (facets and Bragg) and sediment volume, modified to explicitly account for frequency. A special effort was applied for introducing an objective frequency dependence in the classical facets method using developments involving various aspects of the roughness properties, building on previous classical works. The interface and volume components are completed by geoacoustical relationships constraining the range of input parameters, as well as by connection terms that ensure numerical stability. The model proved effective across a frequency range corresponding at least to our available angle/frequency field data. Beyond its wide applicability domain, a key advantage of ESAB is its ability to maintain mathematical simplicity and numerical versatility, akin to its predecessor GSAB while providing a direct physical interpretation of parameters, requiring limited assumptions about the sediment physical nature and accounting for frequency dependence. The model effectiveness is demonstrated by the analysis of a comprehensive dataset from the Concarneau Bay (France), providing backscatter measurements acquired by a calibrated EK80 split-beam echosounder across wide incidence angle (0°–70°) and frequency (35–440 kHz) ranges for seven distinct geological facies. The inversion was performed through a simulated annealing algorithm, providing the three main seafloor parameters together with intermediate results. It provided stable and consistent results over the whole frequency range, confirming ESAB’s capability to accurately fit different angular and frequency response patterns while providing quantified and physically meaningful insights into seafloor characteristics. This dual capability of numerical versatility and physical interpretability makes ESAB particularly valuable for seafloor characterization applications involving multifrequency multibeam echosounders for backscatter angular response measurements.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1574129</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1574129</link>
        <title><![CDATA[Acoustic backscatter processing in GLOBE: an open-source software for echo sounder data analysis]]></title>
        <pubdate>2025-07-08T00:00:00Z</pubdate>
        <category>Technology and Code</category>
        <author>C. Poncelet</author><author>A. Saunier</author><author>A. Gaillot</author><author>G. Billant</author><author>L. Berger</author>
        <description><![CDATA[In order to meet the needs of a wide scientific community and take advantage of large echo sounder datasets collected at sea, Ifremer has developed GLOBE (GLobal Oceanographic Bathymetry Explorer), an open-source software program that integrates tools for bathymetry, water column, and now advanced seafloor backscatter processing. GLOBE follows standardized formats and methodologies, including the International Council For the Exploration of the Sea (ICES) SONAR-netCDF4 standard and the Geohab Backscatter Working Group (BSWG) recommendations, ensuring interoperability and reproducibility. GLOBE provides a comprehensive 3D georeferenced environment for visualizing and analyzing echo sounder data by merging datasets acquired on different platforms at various spatial and temporal scales. The applicability of GLOBE software for seafloor backscatter processing is presented and compared with that of existing tools. Its use is illustrated with a dataset of the multibeam water column and seafloor backscatter acquired by a research vessel and an underwater vehicle of the French Oceanographic Fleet (FOF) in the Tyrrhenian Sea.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1574996</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1574996</link>
        <title><![CDATA[Multispectral backscatter-based characterization of seafloor sediments using calibrated multibeam and tilted single-beam echosounders]]></title>
        <pubdate>2025-07-04T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Ridha Fezzani</author><author>Laurent Berger</author><author>Naig Le Bouffant</author><author>Xavier Lurton</author>
        <description><![CDATA[This study presents a detailed analysis of Angular Response Curves (ARC) extracted from a multi-spectral seabed backscatter dataset utilizing both calibrated single-beam (SBES) and multibeam echosounders (MBES). Five calibrated SBES transducers were tilted from −9° to 70° to measure ARC at different discrete frequencies ranges from 35 kHz to 440 kHz (three to four frequencies per transducer). Additionally, three frequencies −200 kHz, 300 kHz and 400 kHz - were used with the MBES. Experimental data were collected in the Bay of Concarneau, located on the French Northwest coast, across seven different ground-truthed sediment types. The study aims to investigate the effects of frequency and pulse length on ARC shape and intensity. Furthermore, a novel method for estimating seabed angular backscatter from standard SBES volume backscatter strength (Sv) is used. A key aspect of this research is the intercalibration of the multibeam and singlebeam systems to ensure consistency and reliability in MBES backscatter measurements. These findings contribute to a better understanding of acoustic wave interactions with sediment properties across different wavelengths and pulse durations, ultimately improving seabed characterization accuracy.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1572545</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1572545</link>
        <title><![CDATA[Instrumental temperature-dependence of backscatter measurements by a multibeam echosounder: findings and implications]]></title>
        <pubdate>2025-05-30T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Marc Roche</author><author>Tor Inge Birkenes Lønmo</author><author>Ridha Fezzani</author><author>Laurent Berger</author><author>Samuel Deleu</author><author>Hervé Bisquay</author><author>Arnaud Gaillot</author><author>Kris Vanparys</author><author>Jan Vercaemst</author><author>Koen Degrendele</author><author>Florian Barette</author><author>Luciano Emidio Fonseca</author><author>Johan Verstraeten</author><author>Kjell Echholt Nilsen</author><author>Giacomo Montereale-Gavazzi</author><author>Xavier Lurton</author><author>Jean-Marie Augustin</author>
        <description><![CDATA[Multibeam echosounder Backscatter Strength (BS) measurement is a pivotal tool for seabed mapping and monitoring. However, its effective utilization is contingent upon the resolution of challenges such as environmental influences, calibration and repeatability. Natural reference areas offer a pragmatic solution by providing a reliable foundation for backscatter quality control and calibration, ensuring data consistency over time. Recent measurements conducted on the Kwinte reference area (Belgian part of the North Sea) have revealed a significant correlation between measured BS and seawater temperature. This correlation is corroborated by other measurements carried out on the Carré Renard reference area (Bay of Brest, France) and in-tank (by Kongsberg Discovery, Horten, Norway). Significant measured level shifts were currently observed (up to 4 dB per 10°C), depending on signal frequency and angle, and described either as global level shifts or as directivity pattern distortions. Given the negligible impact of sound absorption through the water column, the level-temperature dependence assessed here is regarded as a sensor artifact. This finding underscores a heretofore unrecognized source of MBES-measured level variability. This instrumental temperature-dependence is attributable to variations in the properties of the materials constituting transducers and in their acoustic interaction, which, in turn, affect the sensitivity and directivity of the arrays and influence measured levels. A simple sound-speed-dependent description of in-transducer refraction offers an explanation for these effects but does not fully account for the observed changes in directivity patterns. Hence, it is necessary to consider complex models accounting for material interactions, transducer properties and coupling, and individual calibration. However, these models are challenging to build and implement comprehensively. A systematic cross-calibration during each measurement campaign is considered as a means to account for this variability. This pragmatic approach is demonstrated through its application to a short time series dataset, showcasing its benefits. This research advances key priorities in the concerned scientific community by enhancing the accuracy and reliability of BS as a seabed sediment indicator and refining cross-calibration over natural reference areas. It also advocates for the systematic use of backscatter measurements in marine resource management and habitat monitoring.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1549238</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1549238</link>
        <title><![CDATA[Using seafloor echo-integrated backscatter for monitoring single beam echosounder calibration]]></title>
        <pubdate>2025-05-21T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>N. Le Bouffant</author><author>L. Berger</author><author>R. Fezzani</author>
        <description><![CDATA[IntroductionIn recent years, methods have been developed to calibrate seafloor backscatter measurements from hydrographic multibeam echosounders. Some of these methods involve the use of well-characterized reference areas that consistently exhibit stable backscatter levels over the years. This study investigates the potential of measuring seafloor backscatter over such a known stable area with vertical single beam echosounders, to provide a straightforward monitoring of their calibration.MethodsWe propose a methodology for calculating standard seafloor surface backscattering at normal incidence, utilizing the standard volume backscattering echo-integration technique commonly used in fishery echosounders, which is also applicable to wideband frequency modulation (FM) transmissions. We explain how this technique compares to the typical multibeam echosounder computation, which is based on samples of maximum amplitude.ResultsThe operational accuracy of seafloor backscatter measurements taken over a known stable area is presented, with data collected over several years from various single-beam systems primarily calibrated using the sphere method.DiscussionThe repeatability of the results suggests that such natural seafloor reference areas can serve as a secondary calibration reference for quickly monitoring single-beam echosounders, through a straightforward acquisition and processing approach. While this method may not provide access to all the echosounder features controlled by sphere calibration, it can be used to adjust standard volume and surface backscattering measurements.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1576192</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1576192</link>
        <title><![CDATA[Temporal evolution of anchor tracks on a silty seafloor (Eckernförde Bay/Baltic Sea)]]></title>
        <pubdate>2025-04-15T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Inken Schulze</author><author>Mischa Schönke</author><author>Peter Feldens</author><author>Svenja Papenmeier</author>
        <description><![CDATA[Anchoring activities exert significant physical pressure on seabed, altering benthic habitats through mechanical disturbances. The European Marine Strategy Framework Directive mandates the assessment of such anthropogenic impacts. Evaluating seabed integrity requires an understanding of both the spatial extent of disturbance and the rate of recovery. This study presents multibeam echosounder bathymetry and backscatter from a heavily impacted area in the Bay of Eckernförde, German Baltic Sea, a region with intensive tourist and naval shipping traffic. The data reveal a dense network of anchor tracks, characterized by elongated furrows flanked by mounds to both sides and extensive abrasion zones caused by the anchor chains. The profile of a fresh anchor track shows a depth of −0.3 m and a mound elevation of 0.2 m, both features diminishing by approximately half after 1 year. Its initial anchor impact crater reaches maximum depth of 0.7 m in the silty sediments. Seafloor disturbance extends approximately 3 m to both sides from anchor tracks, affecting approximately 20% of the surveyed area, excluding widespread abrasion zones. To analyze track degradation, a relative timeline was constructed using a topological sorting algorithm and compared with absolute dating based on AIS data. Results indicate slope measurements effectively capture anchor track degradation until morphological equilibrium is reached. Beyond this stage, tracks remain visible in backscatter data by increased intensity along former mounds. This suggests that anchor tracks have a more persistent impact on seabed integrity than bathymetric data indicate. The spatial extent and the long-lasting effect of the anchor tracks highlight the necessity for explicit spatial management strategies to mitigate cumulative impacts on seabed integrity.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1539618</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1539618</link>
        <title><![CDATA[Non-stereotypy (to species) in mysticete downsweeps]]></title>
        <pubdate>2025-04-08T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Paul Nguyen Hong Duc</author><author>Christine Erbe</author><author>Shyam Madhusudhana</author><author>Daniel Wilkes</author><author>Lachlan Gill</author><author>Cristina Tollefsen</author><author>Narissa de Bruin</author><author>Aiyana Erbeking</author><author>Curt Jenner</author><author>Micheline Jenner</author><author>Angela Recalde-Salas</author><author>Chandra P. Salgado Kent</author><author>Kautilya Srivastava</author><author>Chong Wei</author><author>Robert McCauley</author>
        <description><![CDATA[The Australian EEZ provides habitat for ten species of mysticete whales seasonally supporting critical life functions ranging from feeding to breeding. All of these species produce downsweeping calls, which may confound passive acoustic monitoring efforts. In an attempt to optimize a detector for Eastern Indian Ocean pygmy blue whale (EIOPBW) downsweeps, we tried a spectrogram correlator based on confirmed templates and a neural network trained on general blue whale D-calls followed by clustering algorithms. Outputs were manually validated by bioacousticians. We found that downsweeps exhibit significant variability and form a graded continuum of acoustic features, as opposed to clusters. Comparative analysis demonstrated parallels between EIOPBW call variants and downsweeps of other mysticete species, raising concerns about the reliability of assigning calls to species based solely on spectrographic features. Geographical and seasonal patterns of downsweeps were more conclusive for EIOPBW when aligned with known migratory routes and timings. Challenges in automated detection, variability in environmental noise, and human biases in manual classification were acknowledged. To improve species identification, we suggest integrating soft labeling, advanced acoustic transforms, sound propagation corrections, and cross-referenced databases. Until automated methods achieve higher reliability, passive acoustic monitoring will require a multidisciplinary approach incorporating regional ecological insights and manual validation.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1482244</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1482244</link>
        <title><![CDATA[Nocturnal fish chorusing activity in the central Red Sea mesophotic reef zone and adjacent shallow sites]]></title>
        <pubdate>2025-03-21T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Michelle-Nicole Havlik</author><author>Anieka J. Parry</author><author>Alexandra Steckbauer</author><author>Marta Ezeta Watts</author><author>Fabio Marchese</author><author>Francesca Benzoni</author><author>Carlos M. Duarte</author>
        <description><![CDATA[Through sharing characteristics of chorus activity, especially in regions that are particularly data deficient, we can aim at a broader, global understanding of fish chorusing and consequently important spatiotemporal changes in habitat use by schooling fish. Here, we identify seasonal changes in fish chorusing activity using passive acoustic monitoring, in the central Red Sea mesophotic and adjacent shallow coral reef zones. For this study, recorders were placed in the mesophotic coral reef zone (70–80 m), and adjacent shallow reef sites (10 m), over 2 weeks during summer and winter seasons. A total of eleven choruses were identified and catalogued according to timing, location and acoustic characteristics of frequency and sound pressure levels. The presence of choruses in both deep and shallow reef sites is indicative of critical habitat for fish foraging, courtship, spawning, and/or migratory activity. All but two choruses were found to originate at or near the mesophotic sites. Four choruses unique to summer and winter (n=3 and 1 respectively) were most prevalent in soundscapes. Temperature and oxygen levels, measured to document conditions under which the choruses were present, showed little change across the mesophotic zone even between seasons, while daily fluctuation occurred in the adjacent shallow sites in both seasons.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1546280</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1546280</link>
        <title><![CDATA[Multifrequency seafloor acoustic backscatter as a tool for improved biological and geological assessments – updating knowledge, prospects, and challenges]]></title>
        <pubdate>2025-03-05T00:00:00Z</pubdate>
        <category>Mini Review</category>
        <author>Pedro S. Menandro</author><author>Benjamin Misiuk</author><author>Jens Schneider von Deimling</author><author>Alex C. Bastos</author><author>Craig J. Brown</author>
        <description><![CDATA[Multibeam echosounders (MBES) have emerged as a primary tool for seafloor mapping over the past three decades. Technological advancements and improved data processing methods have increased the accuracy and spatial resolution of bathymetric measurements, and have also led to the increasing use of MBES backscatter data for seafloor geological and benthic habitat mapping applications. MBES backscatter is now frequently used to characterize habitat for marine flora and fauna, contribute to the development of effective marine spatial planning and management strategies, and generally better classify the seabed. Recently, further technological advances have enabled the acquisition and analysis of backscatter at multiple sonar operating frequencies (multifrequency backscatter), with follow-on potential benefits for improved seafloor characterization and classification. This review focuses on the currently available peer-reviewed papers related to multifrequency seafloor acoustic backscatter, providing a comprehensive summary of the contributions across different benthic environments, setting the stage for related applications and outlining challenges and research directions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1532714</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1532714</link>
        <title><![CDATA[Deep-learning-based detection of underwater fluids in multiple multibeam echosounder data]]></title>
        <pubdate>2025-02-28T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Tyméa Perret</author><author>Gilles Le Chenadec</author><author>Arnaud Gaillot</author><author>Yoann Ladroit</author><author>Stéphanie Dupré</author>
        <description><![CDATA[Detecting and locating emitted fluids in the water column is necessary for studying margins, identifying natural resources, and preventing geohazards. Fluids can be detected in the water column using multibeam echosounder data. However, manually analyzing the huge volume of this data for geoscientists is a very time-consuming task. Our study investigated the use of a YOLO-based deep learning supervised approach to automate the detection of fluids emitted from cold seeps (gaseous methane) and volcanic sites (liquid carbon dioxide). Several thousand annotated echograms collected from three different seas and oceans during distinct surveys were used to train and test the deep learning model. The results demonstrate first that this method surpasses current machine learning techniques, such as Haar-Local Binary Pattern Cascade. Additionally, we thoroughly analyzed the composition of the training dataset and evaluated the detection performance based on various training configurations. The tests were conducted on a dataset comprising hundreds of thousands of echograms i) acquired with three different multibeam echosounders (Kongsberg EM302 and EM122 and Reson Seabat 7150) and ii) characterized by variable water column noise conditions related to sounder artefacts and the presence of biomass (fishes, dolphins). Incorporating untargeted echoes (acoustic artefacts) in the training set (through hard negative mining) along with adding images without fluid-related echoes are the most efficient way to improve the performance of the model and reduce the false positives. Our fluid detector opens the door for near-real time acquisition and post-acquisition detection with efficiency, reliability and rapidity.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1521958</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1521958</link>
        <title><![CDATA[Assessment of the application of each multibeam echosounder data product for monitoring of Laminaria digitata in the UK]]></title>
        <pubdate>2025-02-26T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Jacob Berry</author><author>Cassandra Nanlal</author>
        <description><![CDATA[Amid warming seas, high rates of pollution and declining fish stocks observed around the UK, the vital role of kelp as ecosystem mediators on our coastlines is increasingly significant; currently estimated at £500 billion. Extensive research on the rapid decline of kelp forests and its potential consequences has prompted the initiation of numerous conservation efforts. This research set out to determine the applicability and efficiency of a less invasive, remote sensing technique for monitoring kelp. A high resolution multibeam echosounder (MBES) survey was performed to acquire depths, backscatter and water column data in an area known to have kelp. An evaluation of different combinations of the MBES data products for kelp forest monitoring was carried out. An image-based processing methodology using a random forests algorithm was used to generate classification models, which were trained and tested using ground truth samples obtained through video imagery. This study reports climbing model accuracy scores from 62.2% (±11%, 1σ) to 90% (±10%, 1σ) on consecutive input of data products, indicating MBES as an effective tool with respect to other technologies. When considering practical difficulties associated with simultaneous record of all data products against their individual value, this study suggests that bathymetry and backscatter products deliver greatest value for distinction of small form kelp, while angular response analysis and water column data deliver lesser value but are required for optimised accuracy.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2025.1527988</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2025.1527988</link>
        <title><![CDATA[Distance and orientation of hydrophones influence the received soundscape in shallow coral reefs]]></title>
        <pubdate>2025-02-13T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Juan Carlos Azofeifa-Solano</author><author>Christine Erbe</author><author>Cristina Tollefsen</author><author>Robert D. McCauley</author><author>Rohan M. Brooker</author><author>Daniel Pygas</author><author>Miles J. G. Parsons</author>
        <description><![CDATA[IntroductionAcoustic monitoring and soundscape analysis provide valuable data for the conservation and restoration of underwater habitats. However, before these methods can be widely implemented for management purposes, it is crucial to validate the ecological relevance of different sampling methodologies and quantify potential biases.MethodsWe investigated how the distance and orientation of an acoustic sensor relative to a target habitat influence the received soundscape. Using a spatial array of hydrophones, we recorded sound at different distances (1 m, 2 m, 5 m) and orientations (vertical vs. horizontal) from a shallow coral reef.ResultsHydrophones oriented horizontally toward the reef exhibited the expected decrease in sound levels with increasing distance. In contrast, hydrophones oriented vertically showed an inverse trend, with lower sound pressure levels at closer distances and higher levels further away.DiscussionThese findings indicate that sensor directivity significantly influences the received soundscape, introducing a potential methodological bias within and across acoustic datasets. To improve the accuracy and comparability of acoustic sampling in coastal habitats, sensor beam patterns should be carefully considered in experimental design.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frsen.2024.1484283</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frsen.2024.1484283</link>
        <title><![CDATA[Identifying community-driven priority questions in acoustic backscatter research]]></title>
        <pubdate>2025-01-07T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Vincent Lecours</author><author>Benjamin Misiuk</author><author>Felix Butschek</author><author>Philippe Blondel</author><author>Giacomo Montereale-Gavazzi</author><author>Vanessa L. Lucieer</author><author>Chris McGonigle</author>
        <description><![CDATA[IntroductionRemotely-sensed acoustic backscatter is an indispensable tool for seabed mapping, among other disciplines. Almost a decade after the GeoHab Backscatter Working Group published its guidelines and recommendations report, new technologies, new challenges and new questions have emerged. Given the range of potential backscatter research avenues, it can be difficult to align research programs with the priorities of the community of practice. Prioritization of backscatter research topics is thus necessary to establish a roadmap for acoustic backscatter research efforts.MethodsWe asked the international community working with acoustic backscatter to submit their priority research questions over a 5- to 10-year horizon. We analyzed and curated a total of 177 research questions from 73 contributors, and the resulting 104 questions were grouped into eight broad recurring themes: “Technologies”, “Calibration”, “Data acquisition and ground-truthing”, “Data processing”, “Post-processing, quality control, data handling, and curation”, “Data analysis”, “Data interpretation”, and “Applications and end uses”. A follow-up survey based on the final list of questions was distributed to characterize the community working with backscatter and to identify key research priorities.ResultsA total of 120 responses originating from 23 countries were used for the analyses. Most respondents were researchers (68%), while others were technicians (25%) or department or program managers (11%), among other roles. Affiliations of respondents included academia (43%), governmental agencies (37%), and industry/private sector (18%). After scaling the responses, the most commonly selected theme was “Post-processing, quality control, data handling, and curation”, followed by “Calibration” and “Data analysis”. Respondents consistently ranked several research questions as priorities. The two questions that were identified as priorities by over 25% of respondents were “How can we move towards absolute calibration of different systems to allow interregional comparisons?”, and “How can we quantify seafloor backscatter quality and develop standards similar to what exists with bathymetry?”.DiscussionAll eight themes are represented in the top 10 priority questions, underscoring the need for contributions to backscatter research from multiple perspectives to advance the field. The ranking of priority questions encourages collaboration within the community and will serve as a roadmap for backscatter research programs over the next decade.]]></description>
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