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Lanyon, Janet M.; Sneath, Helen L.; Long, Trevor; Bonde, Robert K.
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2010 |
Physiological response of wild dugongs (Dugong dugon) to out-of-water sampling for health assessment.
Aquatic Mammals 36(1): 46-58. 2 tabs. 5 figs. DOI: 10.1578/AM.36.1.2010.46. Jan. 2010.
–ABSTRACT: The dugong (Dugong dugon) is a vulnerable marine mammal with large populations living in urban Queensland waters. A mark-recapture program for wild dugongs has been ongoing in southern Queensland since 2001. This program has involved capture and in-water sampling of more than 700 dugongs where animals have been held at the water surface for 5 min to be gene-tagged, measured, and biopsied. In 2008, this program expanded to examine more comprehensively body condition, reproductive status, and the health of wild dugongs in Moreton Bay. Using Sea World's research vessel, captured dugongs were lifted onto a boat and sampled out-of-water to obtain accurate body weights and morphometrics, collect blood and urine samples for baseline health parameters and hormone profiles, and ultrasound females for pregnancy status. In all, 30 dugongs, including two pregnant females, were sampled over 10 d and restrained on deck for up to 55 min each while biological data were collected. Each of the dugongs had their basic temperature-heart rate-respiration (THR) monitored throughout their period of handling, following protocols developed for the West Indian manatee (Trichechus manatus). This paper reports on the physiological response of captured dugongs during this out-of-water operation as indicated by their vital signs and the suitability of the manatee monitoring protocols to this related sirenian species. A recommendation is made that the range of vital signs of these wild dugongs be used as benchmark criteria of normal parameters for other studies that intend to sample dugongs out-of-water.
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Lanyon, Janet M.; Sneath, Helen L.; Long, Trevor
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2012 |
Evaluation of exertion and capture stress in serum of wild dugongs (Dugong dugon).
Jour. Zoo & Wildlife Medicine 43(1): 20–32. 2 tabs. 2 figs.
–ABSTRACT: Seven hundred fifty-one dugongs (Dugong dugon) were pursued, captured, and handled for up to 20 min for population sampling. Fifty of these dugongs were then removed from the water for up to 55 min for comprehensive medical examination. Fifty whole blood and separated serum samples were analyzed for potassium, sodium, chloride, creatinine kinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), urea, creatinine, glucose, anion gap, and total blood CO2. Serum biochemical variables of the dugong were compared with those obtained in previous studies of the related West Indian manatee, a mammal that does not appear to experience capture myopathy based on available data. Differences between these species included higher blood sodium and chloride in dugongs, which may reflect differences in salt balance and renal function, and higher blood lactate and CO2. Some biochemical analytes such as CK and AST, which may be indicative of rhabdomyolysis associated with capture stress myopathy (a potentially fatal condition for which dugongs have been thought to be highly susceptible) were high compared with levels previously measured in wild West Indian manatees (Trichechus latirostris). One of the 50 dugongs had marked elevations of CK and AST but showed no other clinical indications of rhabdomyolysis associated with capture myopathy such as hyperthermia. Rather, generally high levels of lactate, CK, and AST most probably reflect metabolic acidosis resulting from the exertion involved in the pursuit prior to capture. Earlier observations suggesting that dugongs were probably susceptible to capture stress myopathy (based on high serum potassium levels) were not supported by this study. Capture and handling methods currently used on dugongs in this research program do not appear to result in acute capture stress.
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Seddon, Jennifer M.; Ovenden, Jennifer R.; Sneath, Helen L.; Broderick, Damien; Dudgeon, Christine L.; Lanyon, Janet M.
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2014 |
Fine scale population structure of dugongs (Dugong dugon) implies low gene flow along the southern Queensland coastline.
Conservation Genetics, 6 tabs. 2 figs. DOI:10.1007/s10592-014-0624-x. June 2, 2014.
–ABSTRACT: Populations of marine mammals can show the signature of phylogeographical breaks and restricted connectivity despite the apparent lack of physical boundaries in the marine environment and their high dispersal abilities. Dugongs (Dugong dugon) do not appear to undertake regular migrations but may show localised movement related to water temperature or seagrass availability. Previous mitochondrial DNA studies suggested that despite a strong phylogeographic break in the Torres Strait, there is local panmixia in Australian waters. In this study, we conducted a comprehensive study of the four major dugong populations in southern Queensland. We analysed genotypes of 1,293 dugongs based on 24 microsatellite loci from the four major dugong locations in the region (from south to north): Moreton Bay, Great Sandy Straits, Hervey Bay and Shoalwater Bay. Diversity levels were similar across locations (observed heterozygosity 0.48–0.52, allelic richness 4.3–4.5). There was low but significant population differentiation in southern Queensland (FST ranged from 0.005 to 0.040 and Jost's DEST ranged from 0.001 to 0.031 for microsatellite data). Bayesian clustering analysis implemented in STRUCTURE largely distinguished the southern Moreton Bay population from the three more northern populations. Twelve mitochondrial control region haplotypes identified from a subset of 182 samples confirmed significant population structuring (FST ranged from 0.16 to 0.28). These data suggested that the frequency and extent of dugong movements are insufficient to disrupt the long-term existence of at least two breeding populations in southern Queensland.
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Woolford, Lucy; Wong, Arthur; Sneath, Helen L.; Long, Trevor; Boyd, Susan P.; Lanyon, Janet M.
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2015 |
Hematology of dugongs (Dugong dugon) in southern Queensland.
Veterinary Clinical Pathology 44(4): 530–541. 6 tabs. 4 figs. DOI: 10.1111/vcp.12305. Dec. 2015.
–ABSTRACT: Background- Little is known of the hematology of the dugong (Dugong dugon), a secretive and endangered coastal marine mammal.
Objectives- This paper reports hematologic reference intervals (RI) for dugongs and characterizes morphologic, cytochemical, and ultrastructural features of dugong leukocytes.
Methods- Blood was collected from live, apparently healthy dugongs and analyzed using Cell-Dyn 3700 or Sysmex XT-2000iV hematology analyzers. Blood films were subjected to a series of cytochemical stains, and leukocyte structure was examined using transmission electron microscopy.
Results- Reference intervals were established for 14 hematologic variables, total solids, and fibrinogen for 92 dugongs. Significant differences in some variables were found for animal size class, sex, and pregnancy status, and between analyzers. Subadults had higher leukocyte and lymphocyte counts than adults. Males had higher total solids and fibrinogen than females. Pregnant females had higher HCT, MCV, and circulating nucleated RBC, and lower platelet counts than nonpregnant females. Lymphocytes were usually the predominant circulating leukocyte. Heterophil cytoplasmic granules were abundant, fine, round to ovoid, and intensely eosinophilic, and round to ovoid or rod-shaped, and variably electron dense in electron microscopy. Eosinophils contained larger round eosinophilic to orange cytoplasmic granules, which ultrastructurally were bicompartmental with a round eccentric electron-dense core. Cytochemical staining of dugong heterophils suggests biochemical similarity to those of manatees and elephants, and for eosinophils, similarity to those of elephants, ruminants, and equids.
Conclusions- Generation of hematologic RI and characterization of leukocyte morphology improves evaluation of dugong health across this population and serves as a reference for other populations outside southern Queensland.
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Lanyon, Janet M.; Athousis, Chrissa; Sneath, Helen L.; Burgess, Elizabeth A.
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2021 |
Body scarring as an indicator of social function of dugong (Dugong dugon) tusks.
Mar. Mamm. Sci. 37(3): 962-981. https://doi.org/10.1111/mms.12788 July 7, 2021 (publ. online Feb. 26, 2021).
–ABSTRACT: The fully aquatic lifestyle of dugongs means that direct observation of social tusk use is not usually possible. This study used body scarring as an indicator of tusk function by males. Tusk rake scars on 298 live wild dugongs, of both sexes and all sizes, were categorized and counted in over 1,000 photographs, and examined in relation to maturity and reproductive activity over seasons. All dugongs had tusk scars, but adults were the main recipients. Sexually active adults acquired the greatest number of fresh tusk wounds during the mating season. Subadults received fresh rakes at similar numbers year?round. Adult males had more scars on the mid and posterior dorsum, indicating that males direct combative force to these regions of the male body when competing for females. Adult females had heaviest scarring and more tusk puncture wounds on the anterior?mid dorsum and head, suggesting that male dugongs use tusks in sexual coercion. Heavy scarring sustained by solitary calves compared to dependent ones, suggests that mothers afford some protection. Body scarring caused by tusks may serve as an indicator of reproductive contribution of the recipients, providing that successful males are involved in more reproductive competitions, and successful females in more mating events.
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Bibliography and Index of the Sirenia and Desmostylia 