The relationship between acoustic habitat, hearing and tonal vocalizations in the Antillean manatee (<i>Trichechus manatus manatus</i>, Linnaeus, 1758)

Chavarría, Mario Rivera; Castro, José Villaverde; Camacho, Arturo

doi:10.1242/bio.013631

Cited by 18 publications

(8 citation statements)

References 29 publications

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“…This could facilitate larger transmission distances of high-frequency signals 60 . However, a recent study found that frequency bands between 0.5-20 kHz have been shown to propagate efficiently in freshwater, marine and brackish habitats for the Antillean manatee and in seagrass beds for the Florida manatee 59,61 . Furthermore, behavioral audiograms identified hearing capabilities ranging from 0.4 to 90.5 kHz with peak sensitivity at 16 to 18 kHz in Florida manatees 62,63 .…”

Section: Discussionmentioning

confidence: 99%

Manatee calf call contour and acoustic structure varies by species and body size

Brady

Ramos

May‐Collado

et al. 2022

Sci Rep

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Vocal activity and signal characteristics of mammals are driven by several factors that result in both stability and plasticity over multiple time scales. All three extant species of manatee communicate with several calls that are especially important for maintaining contact between cows and calves. Determining if calf calls differ across manatee species will provide insights into the evolution of species-specific acoustic communication traits. We investigated the interspecific differences in the vocalizations of calves of Amazonian manatees (Trichechus inunguis) and the two subspecies of the West Indian manatee (T. manatus). Vocalizations of individual calves were recorded in rehabilitation centers in Brazil, Puerto Rico, the United States, and Mexico. The acoustic structure of calls produced by manatee calves varied between species and with body size. Amazonian manatee calves produced shorter calls with multiple notes at higher frequency while West Indian calves produced modulated calls that were lower in frequency and longer in duration. Smaller West Indian calves produced frequency modulated, hill-shaped calls that flattened with an increase in body length. Our results provide evidence for divergence in the ontogeny of vocalizations across T. manatus and T. inunguis and suggest variation in body size contributed to the evolution of differences in the characteristics of their calls.

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Section: Discussionmentioning

confidence: 99%

Manatee calf call contour and acoustic structure varies by species and body size

Brady

Ramos

May‐Collado

et al. 2022

Sci Rep

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“…Developing improved methods for detecting endangered species where their populations are in decline is crucial to their preservation. Our previous work illustrated the strength of passive acoustics for detecting manatees, and similar methods have been successful in habitats of the West Indian manatee (LaCommare et al, 2008;Gonzalez-Socoloske et al, 2009;Gonzalez-Socoloske and Olivera-Gomez, 2012;Kikuchi et al, 2013;Rivera Chavarria et al, 2015;Guzman and Condit, 2017;Puc-Carrasco et al, 2017;Castelblanco-Martıńez et al, 2018;Rycyk et al, 2021;Rycyk et al, 2022).…”

Section: Discussionmentioning

confidence: 87%

“…In addition, manatees produce a variety of vocalizations including squeaks, screeches, whines, and trills (Umeed et al, 2018;Brady et al, 2020;Baotic et al, 2022) shown to be important for their underwater communication and emitted across various behavioral states (Bengtson and Fitzgerald, 1985;O'Shea and Poche, 2006;Brady et al, 2021). Passive acoustics have been used in many studies to monitor manatees and have yielded up to 100% detection frequencies (LaCommare et al, 2008;Kikuchi et al, 2013;Rivera Chavarria et al, 2015;Rycyk et al, 2021;Rycyk et al, 2022). While the above methodologies have been used to monitor other species of manatee (Florida manatees: Rycyk et al, 2022;Antillean manatees: Ramos et al, 2020), they have been rarely implemented with African manatees.…”

Section: Introductionmentioning

confidence: 99%

Acoustic methods improve the detection of the endangered African manatee

Factheu

Rycyk²,

Kekeunou³

et al. 2023

Front. Mar. Sci.

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The African manatee (Trichechus senegalensis) is an elusive, data-deficient, and endangered species which inhabits marine and freshwater systems throughout Western and Central Africa. A major challenge in understanding the species ecology and distribution is the difficulty in detecting it using traditional visual surveys. The recent invasion of Giant Salvinia (Salvinia molesta) at the most important site for the species in Cameroon further limits their detectability and may restrict their movements and habitat use. To investigate methods’ effectiveness in detecting African manatees, we conducted monthly vessel surveys from which visual point scans, 360° sonar scans, and passive acoustic monitoring were conducted simultaneously at ten locations and over 12 months in Lake Ossa, Cameroon. Manatee detection frequency was calculated for each method and the influence of some environmental conditions on the methods’ effectiveness and manatee detection likelihood was assessed by fitting a binary logistic regression to our data. Detection frequencies were significantly different between methods (p < 0.01) with passive acoustics being the most successful (24.17%; n = 120), followed by the 360° sonar scan (11.67%; n = 120), and the visual point scan (3.33%; n = 120). The likelihood of detecting manatees in Lake Ossa was significantly influenced by water depth (p = 0.02) and transparency (p < 0.01). It was more likely to detect manatees in shallower water depths and higher water transparency. Passive acoustic detections were more effective in uninvaded areas of the Lake. We recommend using passive acoustics to enhance African manatee detections in future surveys.

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“…Our detection capabilities were probably hampered by the manatee's elusive nature, and the noise of the engine is likely to have disturbed manatees in the vicinity of the boat, causing them to flee rapidly from the capture area of the side-scan sonar. There is evidence that manatees are capable of localizing the sounds produced by boats (Colbert-Luke et al, 2015), and of reacting to them; for example, disruption of a manatee's call behaviour has been demonstrated at boat–manatee distances of < 25 m (Rivera-Chavarría et al, 2015). As a boat approaches, manatees respond by increasing their swim speed and orienting towards deeper waters (Nowacek et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

How to detect an elusive aquatic mammal in complex environments? A study of the Endangered Antillean manateeTrichechus manatus manatusin French Guiana

Castelblanco‐Martínez¹,

Reis

Thoisy

2017

Oryx

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The Antillean manatee Trichechus manatus manatus is a cryptic mammal that inhabits, among other areas, murky rivers and estuaries of Central and South America. The difficulty in detecting and counting manatees is an obstacle to monitoring their population status, as traditional count sampling is unsuitable. We conducted a quantitative analysis of the distribution and abundance of the manatee across its known range in the rivers and estuaries of French Guiana, based on data from a range-wide line transect visual survey combined with a side-scan sonar survey, identification of feeding sites, and silent observations at fixed points. A total effective effort of 248 hours and 1,129 km of boat survey was completed. We used two relative abundance indices: the combined encounter rate, which combines encounters per km from either visual or side-scan sonar surveys, and the global detection index, which is defined as the sum of all evidence per unit time. Manatees were detected in all nine study units. Niche modelling was used to analyse the space selection by manatees, and helped to detect differential use of habitats according to the season. The model predicted that coastal areas are used more extensively during the dry season. In the absence of better techniques to detect wild manatees in complex habitats this monitoring protocol may be relevant and replicable in hydrological systems where manatee detectability is constrained by biogeographical characteristics.

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The relationship between acoustic habitat, hearing and tonal vocalizations in the Antillean manatee (Trichechus manatus manatus, Linnaeus, 1758)

Cited by 18 publications

References 29 publications

Manatee calf call contour and acoustic structure varies by species and body size

Manatee calf call contour and acoustic structure varies by species and body size

Acoustic methods improve the detection of the endangered African manatee

How to detect an elusive aquatic mammal in complex environments? A study of the Endangered Antillean manateeTrichechus manatus manatusin French Guiana

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