Bibliography and Index of the Sirenia and Desmostylia  

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"Gaspard, Joseph C.,"

 
 
 Bauer, Gordon Bruce; Colbert, Debborah E.; Gaspard, Joseph C., III; Littlefield, B.; Fellner, Wendi (detail)
   
2003
Underwater visual acuity of Florida manatees.
Intl. Jour. Comp. Psychol. 16: 130-142.
 
 
 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.
 
 
 Colbert, Debborah E.; Gaspard, Joseph C., III; Reep, Roger Lyons; Mann, David A.; Bauer, Gordon Bruce (detail)
   
2009
Four-choice sound localization abilities of two Florida manatees, Trichechus manatus latirostris.
Jour. Exper. Biol. 212(13): 2104-2111.
 
 
 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.
 
 
 Bauer, Gordon B.; Gaspard, Joseph C., III; Colbert, Debborah E.; Leach, Jennifer B.; Stamper, Sarah A.; Mann, David; Reep, Roger (detail)
   
2012
Tactile discrimination of textures by Florida manatees (Trichechus manatus latirostris).
Marine Mammal Science 28(4): E456-E471. 4 figures. DOI: 10.1111/j.1748-7692.2012.00565.x. October 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).
Journal of Experimental Biology 215(9): 1442-1447. 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.
Daryl P. Domning, Research Associate, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, and Laboratory of Evolutionary Biology, Department of Anatomy, College of Medicine, Howard University, Washington, D.C. 20059.
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