|
|
Mann, David A.; Colbert, Debborah E.; Gaspard, Joseph C., III; Casper, Brandon M.; Cook, Mandy L. H.; Reep, Roger Lyons; Bauer, Gordon Bruce
(detail)
|
| |
|
2005 |
Temporal resolution of the Florida manatee (Trichechus manatus latirostris) auditory system.
Jour. Comp. Physiol. A, Sensory, Neural & Behav. Physiol. 191(10): 903-908.
|
|
|
Reep, Roger Lyons; Gaspard, Joseph C., III; Sarko, Diana K.; Rice, Frank L.; Mann, David A.; Bauer, Gordon B.
(detail)
|
| |
|
2011 |
Manatee vibrissae: evidence for a "lateral line" function.
Annals of the New York Academy of Sciences DOI: 10.1111/j.1749-6632.2011.05992.x. Apr. 2011.
–Aquatic mammals use vibrissae to detect hydrodynamic stimuli over a range from 5 to 150 Hz, similar to the range detected by lateral line systems in fishes and amphibians. Manatees possess ?5,300 vibrissae distributed over the body, innervated by ?209,000 axons. This extensive innervation devoted to vibrissae follicles is reflected in enlarged, elaborate somatosensory regions of the gracile, cuneate, and Bischoff's brain-stem nuclei, ventrobasal thalamus, and presumptive somatosensory cortex. Our preliminary psychophysical testing indicates that in Florida and Antillean manatees the Weber fraction for detection thresholds for grating textures ranges from 0.025 to 0.14. At the lower end of this range, sensitivity is comparable to human index finger thresholds. For hydrodynamic stimuli of 5–150 Hz, detection threshold levels for manatees using facial or postfacial vibrissae were substantially lower than those reported for harbor seals and similar to reports of sensitivity for the lateral line systems of some fish. Our findings suggest that the facial and postfacial vibrissae are used to detect hydrodynamic stimuli, whereas only the facial vibrissae are used for direct contact investigation.
|
|
|
Bauer, Gordon B.; Gaspard, Joseph C., III; Colbert, Debborah E.; Leach , Jennifer B.; Stamper , Sarah A.; Mann, David; Reep, Roger Lyons
(detail)
|
| |
|
2012 |
Tactile discrimination of textures by Florida manatees (Trichechus manatus latirostris).
Mar. Mamm. Sci. 28(4): E456-E471. 4 figs. DOI: 10.1111/j.1748-7692.2012.00565.x Oct. 2012 (first published online June 13, 2012).
–ABSTRACT: Two male Florida manatees (Trichechus manatus latirostris) demonstrated sensitive tactile discrimination in a two-alternative forced choice task, using a modified staircase method. Stimuli were acrylic plates with vertical gratings of ridges and grooves. The standard stimulus, present on every trial, had 2 mm gratings and the comparison stimuli had wider gratings. The blindfolded subjects were trained to demonstrate discrimination by pressing the target with wider gratings. Discrimination thresholds (75% correct) for the subjects were 2.05 mm and 2.15 mm, corresponding to Weber fractions of 0.025 and 0.075, respectively. These results indicate thresholds on similar stimuli comparable to humans (index finger tasks) and better than harbor seals, Phoca vitulina, and the closely related Antillean manatee, Trichechus manatus manatus. Memory for the tactile task was quite stable for both subjects, over 2 yr in the case of one of the subjects. Video analysis of responses indicated that bristle-like hairs, perioral bristles, and skin on the oral disk were involved in the discrimination response.
|
|
|
Gaspard, Joseph C., III; Bauer, Gordon Bruce; Reep, Roger Lyons; Dziuk, Kimberly; Cardwell, Adrienne; Read, LaToshia; Mann, David A.
(detail)
|
| |
|
2012 |
Audiogram and auditory critical ratios of two Florida manatees (Trichechus manatus latirostris).
Jour. Exper. Biol. 215(9): 1442-1447. DOI:10.1242/jeb.089201. May 2012.
–There is also a comment on this article by Kathryn Knight on p. i of this issue.
ABSTRACT: Manatees inhabit turbid, shallow-water environments and have been shown to have poor visual acuity. Previous studies on hearing have demonstrated that manatees possess good hearing and sound localization abilities. The goals of this research were to determine the hearing abilities of two captive subjects and measure critical ratios to understand the capacity of manatees to detect tonal signals, such as manatee vocalizations, in the presence of noise. This study was also undertaken to better understand individual variability, which has been encountered during behavioral research with manatees. Two Florida manatees (Trichechus manatus latirostris) were tested in a go/no-go paradigm using a modified staircase method, with incorporated 'catch' trials at a 1: 1 ratio, to assess their ability to detect single-frequency tonal stimuli. The behavioral audiograms indicated that the manatees' auditory frequency detection for tonal stimuli ranged from 0.25 to 90.5 kHz, with peak sensitivity extending from 8 to 32 kHz. Critical ratios, thresholds for tone detection in the presence of background masking noise, were determined with one-octave wide noise bands, 7-12 dB (spectrum level) above the thresholds determined for the audiogram under quiet conditions. Manatees appear to have quite low critical ratios, especially at 8 kHz, where the ratio was 18.3 dB for one manatee. This suggests that manatee hearing is sensitive in the presence of background noise and that they may have relatively narrow filters in the tested frequency range.
|
|
|
|
Gaspard, Joseph C., III; Bauer, Gordon B.; Reep, Roger L.; Dziuk, Kimberly; Read, LaToshia; Mann, David A.
(detail)
|
| |
|
2013 |
Detection of hydrodynamic stimuli by the Florida manatee (Trichechus manatus latirostris).
Jour. Comp. Physiol. A - Neuroethology Sensory Neural & Behav. Physiol. 199(6): 441-450. 4 tabs. 5 figs. DOI: 10.1007/s00359-013-0822-x. May 10, 2013.
–ABSTRACT: Florida manatees inhabit the coastal and inland waters of the peninsular state. They have little difficulty navigating the turbid waterways, which often contain obstacles that they must circumnavigate. Anatomical and behavioral research suggests that the vibrissae and associated follicle–sinus complexes that manatees possess over their entire body form a sensory array system for detecting hydrodynamic stimuli analogous to the lateral line system of fish. This is consistent with data highlighting that manatees are tactile specialists, evidenced by their specialized facial morphology and use of their vibrissae during feeding and active investigation/manipulation of objects. Two Florida manatees were tested in a go/no-go procedure using a staircase method to assess their ability to detect low-frequency water movement. Hydrodynamic vibrations were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz, which are below the apparent functional hearing limit of the manatee. The manatees detected particle displacement of less than 1??m for frequencies of 15–150 Hz and of less than a nanometer at 150 Hz. Restricting the facial vibrissae with various size mesh openings indicated that the specialized sensory hairs played an important role in the manatee's exquisite tactile sensitivity.
|
|
|
Colbert-Luke, Debborah E.; Gaspard, Joseph C., III; Reep, Roger Lyons; Bauer, Gordon B.; Dziuk, Kimberly; Cardwell, Adrienne; Mann, David A.
(detail)
|
| |
|
2015 |
Eight-choice sound localization by manatees: performance abilities and head related transfer functions.
Jour. Compar. Physiol. A 201(2): 249-259. Feb. 2015.
–ABSTRACT: Two experiments investigated the ability and means by which two male Florida manatees (Trichechus manatus latirostris) may determine the direction of a sound source. An eight-choice discrimination paradigm was used to determine the subjects' sound localization abilities of five signal conditions covering a range of frequencies, durations, and levels. Subjects performed above the 12.5 % chance level for all broadband frequencies and were able to localize sounds over a large level range. Errors were typically located to either side of the signal source location when presented in the front 180° but were more dispersed when presented from locations behind the subject. Front-to-back confusions were few and accuracy was greater when signals originated from the front 180°. Head-related transfer functions were measured to determine if frequencies were filtered by the manatee body to create frequency-specific interaural level differences (ILDs). ILDs were found for all frequencies as a function of source location, although they were largest with frequencies above 18 kHz and when signals originated to either side of the subjects. Larger ILDs were found when the signals originated behind the subjects. A shadowing-effect produced by the body may explain the relatively low occurrence of front-back confusions in the localization study.
|
|
|
Takeuchi, Noel; Walsh, Michael T.; Bonde, Robert K.; Powell, James A.; Bass, Dean A.; Gaspard, Joseph C., III; Barber, David S.
(detail)
|
| |
|
2016 |
Baseline reference range for trace metal concentrations in whole blood of wild and managed West Indian manatees (Trichechus manatus) in Florida and Belize.
Aquatic Mammals 42(4): 440-453. 5 tabs. doi:10.1578/AM.42.4.2016.440. Dec. 2016.
–ABSTRACT: The West Indian manatee (Trichechus manatus) is exposed to a number of anthropogenic influences, including metals, as they inhabit shallow waters with close proximity to shore. While maintaining homeostasis of many metals is crucial for health, there is currently no baseline reference range that can be used to make clinical and environmental decisions for this endangered species. In this study, whole blood samples from 151 manatees were collected during health assessments performed in Florida and Belize from 2008 through 2011. Whole blood samples (n = 37) from managed care facilities in Florida and Belize from 2009 through 2011 were also used in this study. The concentrations of 17 metals in whole blood were determined, and the data were used to derive a baseline reference range. Impacts of capture location, age, and sex on whole blood metal concentrations were examined. Location and age were related to copper concentrations as values were significantly higher in habitats near urban areas and in calves. Copper may also be a husbandry concern as concentrations were significantly higher in managed manatees (1.17 ± 0.04 ppm) than wild manatees (0.73 ± 0.02 ppm). Zinc (11.20 ± 0.30 ppm) was of special interest as normal concentrations were two to five times higher than other marine mammal species. Arsenic concentrations were higher in Belize (0.43 ± 0.07 ppm), with Placencia Lagoon having twice the concentration of Belize City and Southern Lagoon. Selenium concentrations were lower (0.18 ± 0.09 ppm) than in other marine mammal species. The lowest selenium concentrations were observed in rehabilitating and managed manatees which may warrant additional monitoring in managed care facilities. The established preliminary baseline reference range can be used by clinicians, biologists, and managers to monitor the health of West Indian manatees.
|
|
|
Gaspard, Joseph C., III; Bauer, Gordon B.; Mann, David A.; Boerner, Katharine; Denum, Laura; Frances, Candice; Reep, Roger Lyons
(detail)
|
| |
|
2017 |
Detection of hydrodynamic stimuli by the postcranial body of Florida manatees (Trichechus manatus latirostris).
Jour. Comp. Physiol. A 203: 111–120. 2 tabs. 4 figs. DOI 10.1007/s00359-016-1142-8. Publ. online Feb. 13, 2017.
–ABSTRACT: Manatees live in shallow, frequently turbid waters. The sensory means by which they navigate in these conditions are unknown. Poor visual acuity, lack of echolocation, and modest chemosensation suggest that other modalities play an important role. Rich innervation of sensory hairs that cover the entire body and enlarged somatosensory areas of the brain suggest that tactile senses are good candidates. Previous tests of detection of underwater vibratory stimuli indicated that they use passive movement of the hairs to detect particle displacements in the vicinity of a micron or less for frequencies from 10 to 150 Hz. In the current study, hydrodynamic stimuli were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz. Go/no-go tests of manatee postcranial mechanoreception of hydrodynamic stimuli indicated excellent sensitivity but about an order of magnitude less than the facial region. When the vibrissae were trimmed, detection thresholds were elevated, suggesting that the vibrissae were an important means by which detection occurred. Manatees were also highly accurate in two-choice directional discrimination: greater than 90% correct at all frequencies tested. We hypothesize that manatees utilize vibrissae as a three-dimensional array to detect and localize low-frequency hydrodynamic stimuli.
|
|
|
Meyer, Wynn K.; Jamison, Jerrica; Richter, Rebecca; Woods, Stacy E.; Partha, Raghavendran; Kowalczyk, Amanda; Kronk, Charles; Chikina, Maria; Bonde, Robert K.; Crocker, Daniel E.; Gaspard, Joseph; Lanyon, Janet M.; Marsillach, Judit; Furlong, Clement E.; Clark, Nathan L.
(detail)
|
| |
|
2018 |
Ancient convergent losses of Paraoxonase 1 yield potential risks for modern marine mammals.
Science 361(6402): 591-592. doi:10.1126/science.aap7714. Aug. 10, 2018.
|
|
Bibliography and Index of the Sirenia and Desmostylia 