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Kikuchi, Mumi; Suzuki, Miwa; Ueda, Keiichi; Miyahara, Hirokazu; Uchida, Senzo
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2011 |
The differences in behavioral responses to a net obstacle between day and night in captive manatees: does entanglement happen at night?
Fisheries Science 77(5): 795-798. 2 tables. 1 fig. DOI: 10.1007/s12562-011-0388-x. Sept. 2011.
–ABSTRACT: Entanglement in fishing gear occurs in endangered manatees and may result in serious injury or death. Such incidents may happen more frequently at night when the animal's visual sense is limited. In this study, we examined the differences in behavioral response of captive manatees to a net obstacle during light (day) and dark (night) periods. We used a plastic net as the obstacle, and video-recorded the manatees' behavior. The experiments showed that captive manatees avoided the obstacle during the day more frequently than at night, which suggests that the manatees can perceive the obstacle more readily during light periods. However, there was no difference in the frequency of bumping or actively touching the obstacle between light and dark periods. The results suggest that the manatees can recognize the net obstacle even at night by purposely touching it, but they avoid it less frequently, and that entanglement during light periods may occur during accidental bumping, rather than from a failure to recognize it altogether.
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Suzuki, Akihiko; Ueda, Keiichi; Segawa, Takao; Suzuki, Miwa
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2019 |
Fecal microbiota of captive Antillean manatee Trichechus manatus manatus.
FEMS Microbiology Letters 366(11): doi.org/10.1093/femsle/fnz134 June 18, 2019.
–ABSTRACT: Herbivorous animals have unique intestinal microbiota that greatly helps with plant digestion in the host; however, knowledge on the microbiota of marine herbivores is limited. To better understand the taxonomy of intestinal microbiota in manatees, and the possible effects of captive conditions on that, we characterized the fecal microbiota of captive Antillean manatee Trichechus manatus manatus and compared the bacterial community with that of wild Florida manatees Trichechus manatus latirostris. Fecal samples were collected from four captive Antillean manatees in Ocean Expo Park, Okinawa, Japan. The high-quality sequences of the V3–V4 region of bacterial 16S rRNA obtained using an Illumina MiSeq platform were assigned to 16 bacterial phyla, and the most dominant was Firmicutes (84.05 ± 3.50%), followed by Bacteroidetes (8.60 ± 1.71%). Seven of the top 20 bacterial genera were responsible for hydrolyzing cellulose and metabolizing bile acid. The microbiota composition was remarkably different from that found in wild Florida manatees and more diverse than the composition in wild Florida manatees; hence, this result may be dependent on a captive environment. Our results highlight the unique intestinal microbiota in captive manatees, reflecting their diet and possibly an impact of the captive environment.
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Bibliography and Index of the Sirenia and Desmostylia 