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Castelblanco-Martínez, Delma Nataly; Padilla-Sáldivar, Janneth A.; Hernández-Arana, Héctor Abuid; Slone, D. H.; Reid, James P.; Morales-Vela, Benjamín
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2012 |
Movement patterns of Antillean manatees in Chetumal Bay (Mexico) and coastal Belize: A challenge for regional conservation.
Mar. Mamm. Sci. 29(2): E166-E182. 3 tabs. 5 figs. DOI: 10.1111/j.1748-7692.2012.00602.x Apr. 2013 (publ. online Sept. 17, 2012).
–ABSTRACT: Information from 15 satellite-tracked Antillean manatees (Trichechus manatus manatus) was analyzed in order to assess individual movements, home ranges, and high-use areas for conservation decisions. Manatees were captured in Chetumal Bay, Mexico, and tagged with Argos-monitored satellite transmitters. Location of the manatees and physical characteristics were assessed to describe habitat properties. Most manatees traveled to freshwater sources. The Maximum Area Size (MAS) for each manatee was determined using the observation-area method. Additional kernel densities of 95% home range and 50% Center of Activity (COA) were also calculated, with manatees having 1–3 COAs. Manatees exhibited two different movement patterns: remaining in Chetumal Bay, and long-distance (up to 240 km in 89 d). The residence time in Chetumal Bay was higher for females (89.6% of time) than for males (72.0%), but the daily travel rate (0.4–0.5 km/d) was similar for both sexes. Most of the COAs fell within Natural Protected Areas (NPA). However, manatees also travel for long distances into unprotected areas, where they face uncontrolled boat traffic, fishing activities, and habitat loss. Conservation of movement corridors may promote long-distance movements and facilitate genetic exchange.
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Stith, Bradley M.; Slone, D. H.; De Wit, Martine; Edwards, Holly H.; Langtimm, Catherine A.; Swain, E. D.; Soderqvist, L. E.; Reid, James P.
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2012 |
Passive thermal refugia provided warm water for Florida manatees during the severe winter of 2009-2010.
Marine Ecology Progress Series 462: 287-301. DOI:10.3354/meps09732. Aug. 21, 2012.
–ABSTRACT: Haloclines induced by freshwater inflow over tidal water have been identified as an important mechanism for maintaining warm water in passive thermal refugia (PTR) used by Florida manatees Trichechus manatus latirostris during winter in extreme southwestern Florida. Record-setting cold during winter 2009-2010 resulted in an unprecedented number of manatee deaths, adding to concerns that PTR may provide inadequate thermal protection during severe cold periods. Hydrological data from 2009-2010 indicate that 2 canal systems in the Ten Thousand Islands (TTI) region acted as PTR and maintained warm bottom-water temperatures, even during severe and prolonged cold periods. Aerial survey counts of live and dead manatees in TTI during the winter of 2009-2010 suggest that these PTR were effective at preventing mass mortality from hypothermia, in contrast to the nearby Everglades region, which lacks similar artificial PTR and showed high manatee carcass counts. Hydrological data from winter 2008-2009 confirmed earlier findings that without haloclines these artificial PTR may become ineffective as warm-water sites. Tidal pumping of groundwater appears to provide additional heat to bottom water during low tide cycles, but the associated thermal inversion is not observed unless salinity stratification is present. The finding that halocline-driven PTR can maintain warm water even under extreme winter conditions suggests that they may have significant potential as warm-water sites. However, availability and conflicting uses of freshwater and other management issues may make halocline-driven PTR unreliable or difficult to manage during winter.
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Castelblanco-Martínez, Delma Nataly; Slone, D. H.; Landeo-Yauri, S. S.; Ramos, E.; Alvarez-Aleman, A.; et al.
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2021b |
Analysis of body condition indices reveals different ecotypes of the Antillean manatee.
Sci. Repts. 11(19451): 6 tabs. 6 figs. https://doi.org/10.1038/s41598-021-98890-0 Sept. 30, 2021.
–ABSTRACT: Assessing the body condition of wild animals is necessary to monitor the health of the population and is critical to defining a framework for conservation actions. Body condition indices (BCIs) are a non-invasive and relatively simple means to assess the health of individual animals, useful for addressing a wide variety of ecological, behavioral, and management questions. The Antillean manatee (Trichechus manatus manatus) is an endangered subspecies of the West Indian manatee, facing a wide variety of threats from mostly human-related origins. Our objective was to define specific BCIs for the subspecies that, coupled with additional health, genetic and demographic information, can be valuable to guide management decisions. Biometric measurements of 380 wild Antillean manatees captured in seven different locations within their range of distribution were obtained. From this information, we developed three BCIs (BCI1?=?UG/SL, BCI2?=?W/SL3, BCI3?=?W/(SL*UG2)). Linear models and two-way ANCOVA tests showed significant differences of the BCIs among sexes and locations. Although our three BCIs are suitable for Antillean manatees, BCI1 is more practical as it does not require information about weight, which can be a metric logistically difficult to collect under particular circumstances. BCI1 was significantly different among environments, revealing that the phenotypic plasticity of the subspecies have originated at least two ecotypes -- coastal marine and riverine -- of Antillean manatees.
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Bibliography and Index of the Sirenia and Desmostylia 