Jarriel
Sierra
Jarriel
Sierra
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ArticleUnidentified fish sounds as indicators of coral reef health and comparison to other acoustic methods(Frontiers Media, 2024-02-29) Jarriel, Sierra D. ; Formel, Nathan ; Ferguson, Sophie R. ; Jensen, Frants H. ; Apprill, Amy ; Mooney, T. AranThe global decline of coral reefs is a major contributor to the global biodiversity crisis and requires improved monitoring at these critically important habitats. Non-invasive passive acoustic assessments may address this need, leveraging the rich variety and spatiotemporal variability of biological sounds present in coral reef environments and offering near-continuous temporal coverage. Despite this, acoustic metrics that reliably represent coral reef health are still debated, and ground-truthing of methods is limited. Here we investigated how the prevalence of low frequency biotic sounds (without species information) relates to coral reef health, providing a foundation from which one can compare assessment methods. We first quantified call rates of these low frequency sounds for three reefs exhibiting different community assemblages around St. John, U.S. Virgin Islands, by manually annotating presumed fish noises for 1 min every 30 min across 8 days for each site. Annotated days were selected at key points across lunar cycles. These call rates were then compared with traditional visual surveys, and several acoustic methods and indices commonly used in underwater soundscape research. We found that, overall, manually detected fish call rates successfully differentiated between the three reefs, capturing variation in crepuscular activity levels–a pattern consistent with previous work that highlights the importance of diel choruses. Moreover, fish vocal rates were predictors of hard coral cover, fish abundance, and fish species richness, while most acoustic indices failed to parse out fine distinctions among the three sites. Some, such as the Acoustic Complexity Index, failed to reveal any expected differences between sites or times of day, while the Bioacoustic Index could only identify the most acoustically active reef, otherwise having weak correlations to visual metrics. Of the indices tested, root-mean-squared sound pressure level and Acoustic Entropy, both calculated in the low frequency fish band (50–1,200 Hz), showed the strongest association with visual health measures. These findings present an important step toward using soundscape cues for reef health assessments. The limited generalizability of acoustic indices across different locations emphasizes the need for caution in their application. Therefore, it is crucial to improve methods utilizing fish sounds, such as automatic fish call detectors that are able to generalize well to new soundscapes.
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ArticleRice’s whale occurrence in the western Gulf of Mexico from passive acoustic recordings(Wiley, 2024-02-13) Soldevilla, Melissa S. ; Debich, Amanda J. ; Perez-Carballo, Itzel ; Jarriel, Sierra ; Frasier, Kaitlin E. ; Garrison, Lance P. ; Gracia, Adolfo ; Hildebrand, John A. ; Rosel, Patricia E. ; Serrano, ArturoRice's whales (Balaenoptera ricei) are one of the most endangered marine mammal species in the world. Their known distribution is restricted to the Gulf of Mexico (GoMx) and basic knowledge of their ecology is limited. In their core distribution area along the northeastern GoMx shelf break (Rosel & Garrison, 2021), their abundance was estimated at 51 individuals, 95% CI [20, 130], based on line transect surveys conducted during 2017 and 2018 (Garrison et al., 2020). Most Rice's whale sightings and acoustic detections during the last 30 years occur in this area off the northwestern coast of Florida (Rice et al., 2014; Rosel et al., 2021; Širović et al., 2014; Soldevilla et al., 2017; Soldevilla, Ternus, et al., 2022). While visual sightings are rare (e.g., Rosel et al., 2021), recent passive acoustic detections during one year of recordings (Soldevilla, Debich, et al., 2022) establish that they routinely occur along the shelf break of the northwestern GoMx off Louisiana as well. Currently, Rice's whales are only known to occur within U.S. waters of the northern GoMx, although whaling records (Reeves et al., 2011) suggest they were distributed more broadly across the GoMx historically. Understanding their range and distribution is important for evaluating the impacts of human activities, including climate change, that threaten their long-term survival. Considering the high levels of anthropogenic activity throughout the GoMx (e.g., oil and gas exploration and extraction, fisheries, shipping, and oil spills), a comprehensive knowledge of the current distribution of Rice's whales is needed to understand the risk of these activities to the whales and to develop effective recovery and conservation strategies for this endangered species (Rosel et al., 2016).