Movements and habitat use of the Florida manatee (Trichechus manatus latirostris) in the northern Gulf of Mexico
No abstract available.
Alabama, Florida, Louisiana, Mississippi, Texas↗
Geology topics
Robert Bonde
Publications and source records attributed to Robert Bonde.
Genetic connectivity of the West Indian manatee in the southern range and limited evidence of hybridization with Amazonian manatees
The Antillean subspecies of the West Indian manatee is classified as endangered by the International Union for the Conservation of Nature (IUCN) Red List. In Brazil, the manatee population is listed as endangered with an estimated population size of 500–1,000. Historic hunting, recent habitat degradation, and fisheries bycatch have decreased the population size. The Amazonian manatee is listed as vulnerable by the IUCN with unknown population sizes within Brazil. The Antillean manatee occurs in sympatry with the Amazonian manatee in Brazil and hybridization has been previously indicated. To provide information on the genetic structure, diversity, and degree of hybridization in the sympatric zone near the Amazon River mouth, the mitochondrial DNA control region and 13 nuclear microsatellite markers were assessed on the two species. Samples were analyzed from the Antillean subspecies across its distribution in Brazil ( n = 78) and from the Amazonian species ( n = 17) at the Amazon River mouth and inland mainstem river. To assess the previously defined evolutionary significant units of Antillean manatees in the area, an additional 11 samples from Venezuela and Guyana were included. The Antillean manatee was found to be a single population in Brazil and had lower than average number of alleles (3.00), expected heterozygosity (0.34), and haplotype diversity (0.15) when compared to many other manatee populations. The low values may be influenced by the small population size and extended pressures from anthropogenic threats. Gene flow was identified with Venezuela/Guyana in admixed Antillean Brazil samples, although the two populations were found to be moderately divergent. The nuclear loci in Venezuela/Guyana Antillean manatee samples indicated high differentiation from the samples collected in the Amazon River ( F ST = 0.35 and R ST = 0.18, p = 0.0001). No indication of nuclear hybridization was found except for a single sample, “Poque” that had been identified previously. The distribution of Antillean manatees in Brazil is extensive and the areas with unique habitat and threats would benefit from independent management and conservation actions. Gene flow, resulting in genetic diversity and long-term population stability, could be improved in the southern range through habitat restoration, and the establishments of travel corridors and protected areas, which are particularly important for successful parturition and neonatal calf survival.
Frontiers in Marine Science↗
Genetics as a tool for conservation and management of West Indian manatee populations in Brazil
A study conducted by the National Center for Research and Conservation of Aquatic Mammals (CMA), United States Geological Survey Wetland and Aquatic Research Center, and partner researchers found that the marine Antillean manatee ( Trichechus manatus manatus ) has low genetic diversity in regions where there are territorial interfaces with the Amazonian manatee ( Trichechus inunguis ). The study was published as an article in the journal, Frontiers in Marine Science.
Sirenews↗
Serum iron analytes in healthy and diseased Florida manatees (Trichechus manatus latirostris)
Serum iron concentration is usually decreased in true iron deficiency and with inflammatory disease in man and domestic animals. Serum total iron binding capacity (TIBC) may be increased in true iron deficiency and decreased with inflammatory disease. This prospective study was designed to measure serum iron analytes in healthy free-ranging and housed Florida manatees (Trichechus manatus latirostris) of both sexes and various ages and to evaluate the effects of diseases common to manatees on these analytes. Blood samples were collected without anticoagulant from 137 healthy free-ranging manatees, 90 healthy housed manatees and 74 free-ranging diseased manatees, and serum was prepared by centrifugation. Serum iron concentration and unsaturated iron binding capacity were measured colourimetrically, and TIBC and percent transferrin saturation with iron were calculated. Serum amyloid A (SAA) was measured to assist in the health assessment of manatees and provide evidence of inflammation in diseased manatees. Based on the serum iron analytes, iron availability was lower in immature manatees compared with adults, and it was lower in housed manatees compared with free-ranging manatees. In contrast to other mammals studied, serum iron concentration was elevated rather than depressed in late pregnancy. Serum iron concentrations and transferrin saturation with iron percentages were significantly lower, and SAA concentrations were significantly higher, in diseased (ill and injured) manatees compared with healthy manatees. Serum iron concentration and transferrin saturation with iron values were negatively correlated with SAA concentrations, and manatees with the highest SAA concentrations had lower serum TIBC values. These findings indicate that inflammation is the major factor responsible for alterations in iron analytes in diseased manatees. Consequently, hypoferraemia may be used as supportive evidence of inflammatory disease in manatees (unless haemorrhage is also present). A decision threshold of ≤13.8 μmol/l was determined for hypoferraemia using receiver operating curve analysis. Based on studies in man and domestic animals, iron therapy is unnecessary for manatees with hypoferraemia associated with inflammation and has the potential for causing tissue damage and increased susceptibility to bacterial infections.
Florida↗
Enhancing reproductive assessments of the Florida manatee Trichechus manatus latirostris by establishing optimal time period and inhibin B baseline concentrations
The Florida manatee Trichechus manatus latirostris occupies coastal and riverine habitats that may influence the species’ endogenous biological rhythms, including its reproductive potential. Inhibin B provides a biomarker of gonadal function and reproductive potential in humans and other eutherian mammals. This study examined the influence of size, sex, and time of year on inhibin B levels in manatees sampled among 3 habitats with varying degrees of environmental stress in Florida. Inhibin B levels in 38 males averaged (±SE) 4.90 ± 0.23 pg ml -1 ; the average level in 31 females was 5.63 ± 0.46 pg ml -1 . Elevated patterns in inhibin B were exhibited between mid-March and mid-August corresponding to increased mating activity and testicular function, with significant differences in inhibin B levels between male and female manatees (p = 0.03) throughout the year. No significant differences in inhibin B were detected between low- and high-impacted sampling locations during winter, suggesting the potential influence of environmental stress on manatee reproduction may be best examined between mid-March and mid-August—the midpoint of the reproductively active, non-winter time period. Establishing temporal baselines for inhibin B values may be useful in assessing manatee reproductive status and potential conservation threats, shedding light on fertility potential, and enabling future assessment of the effects of stressors on reproduction in Florida manatees.
Florida↗