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Lanyon, Janet M.; Limpus, Colin J.; Marsh, Helene D.
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1989 |
Dugongs and turtles: grazers in the seagrass system. In: A. W. D. Larkum, A. J. McComb & S. A. Shepherd (eds.), Biology of seagrasses: a treatise on the biology of seagrasses with special reference to the Australian region.
New York, Elsevier Science Publ. Co., Inc. (885 pp.): 610-634. 1 tab. 5 figs.
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Lanyon, Janet M.; Marsh, Helene D.
(detail)
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1995 |
Digesta passage times in the dugong.
Austral. Jour. Zool. 43(2): 119-127. 3 tabs. 1 fig.
–Captive dugongs kept on a low-fiber, low-intake diet at Jakarta exhibited very slow passage times of 146-166 hours, similar to those of T. manatus. This is attributed to the long digestive tract, and results in almost complete digestion of low-fiber food.
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Lanyon, Janet M.
(detail)
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2003 |
Distribution and abundance of dugongs in Moreton Bay, Queensland, Australia.
Wildlife Research 30(4): 397-409. 4 tabs. 5 figs.
–Results of aerial surveys conducted in 1995.
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Lanyon, Janet M.; Sanson, Gordon D.
(detail)
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2006a |
Degenerate dentition of the dugong (Dugong dugon), or why a grazer does not need teeth: morphology, occlusion and wear of mouthparts.
Jour. Zool. 268(2): 133-152. 4 tabs. 12 figs. https://doi.org/10.1111/j.1469-7998.2005.00004.x Feb. 2006.
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Lanyon, Janet M.; Sanson, Gordon D.
(detail)
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2006b |
Mechanical disruption of seagrass in the digestive tract of the dugong.
Jour. Zool. 270(2): 277-289. 4 tabs. 8 figs. . https://doi.org/10.1111/j.1469-7998.2006.00135.x Oct. 2006.
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Lanyon, Janet M.; Sneath, Helen L.; Long, Trevor; Bonde, Robert K.
(detail)
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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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Burgess, Elizabeth A., Lanyon, Janet M.; Keeley, Tamara
(detail)
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2012 |
Testosterone and tusks: maturation and seasonal reproductive patterns of live, free-ranging male dugongs (Dugong dugon) in a subtropical population.
Reproduction 143(5):683-697. 9 figures. DOI: 10.1530/REP-11-0434. May 1, 2012.
–ABSTRACT: Knowledge of male reproductive status and activity in free-ranging animals is vital to understanding reproductive patterns and population dynamics. Until now, almost all information regarding reproductive behavior of the dugong, a cryptic marine mammal, has relied on post-mortem examination. We examined the relationships between body length, tusk eruption (secondary sexual characteristic), seasonality, and group association on fecal testosterone metabolite concentrations in 322 free-ranging dugongs (159 males, 163 females) in subtropical Moreton Bay, Australia. Fecal testosterone concentrations demonstrated biologically meaningful differences in testicular activity between sexes and across reproductive/age classes, and were correlated with circulating concentrations in serum. Male dugongs have a pre-reproductive period that persists until a body length of 240 cm is achieved. Puberty apparently occurs between 240 and 260 cm body length when fecal testosterone levels increase fourfold (>500 ng/g) over juvenile levels, and is associated with tusk eruption. However, social maturity may be delayed until male dugongs are larger than 260 cm with well-developed tusks. In mature males, the lowest (<500 ng/g) fecal testosterone concentrations occur in the austral autumn months with maximal concentrations in September-October, coincident with the onset of a spring mating season. During spring, solitary mature males had fecal testosterone concentrations double those of mature males sampled within groups, potentially suggesting a mating strategy involving roving of reproductively active males. This study demonstrates that single-point physiological data from individuals across a population have value as indicators of reproductive processes. Our approach provides an efficacious non-lethal method for the census of reproductive status and seasonality in live male dugongs.
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Burgess, Elizabeth A.; Lanyon, Janet M.; Brown, Janine L.; Blyde, David; Keeley, Tamara
(detail)
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2012 |
Diagnosing pregnancy in free-ranging dugongs using fecal progesterone metabolite concentrations and body morphometrics: a population application.
General and Comparative Endocrinology 177(1): 82-92. 2 tabs. 8 figs. DOI: 10.1016/j.ygcen.2012.02.008. May 15, 2012.
–ABSTRACT: Assessing reproductive status and monitoring reproductive rates is important in the effective management of vulnerable marine mammal species such as the dugong (Dugong dugon). Knowledge of the reproductive physiology of this species is limited, and determining reproductive parameters (e.g., sexual maturation, pregnancy, and reproductive senescence) has been restricted by a lack of non-lethal methods for assessing reproductive status in free-ranging individuals. The aim of this study was to develop a method to identify pregnant individuals in a wild dugong population. Using an enzyme immunoassay, we quantified concentrations of fecal progesterone metabolites (fP) in 322 dugongs, including confirmed pregnant females (n=10), presumed non-pregnant adult females (n=25), juvenile females (n=24), subadult females (n=41), adult females of unknown pregnancy state (n=63), and males of all sizes (n=159). External body morphometrics of each dugong were measured, and confirmation of pregnancy in adult female dugongs was determined by ultrasonography or observation of subsequent neonates. Concentrations of fP were different between sexes and reproductive size classes (P<0.001), and similar to 30-fold higher in confirmed pregnant dugongs (2017-7760ng/g) compared to presumed non-pregnant females (30-221ng/g), juvenile females (29-195ng/g), and males (24-261ng/g) (P<0.001). Body measures of maximum and anal girths, and teat length were all greater in confirmed pregnant females than presumed non-pregnant females (all P<0.05). We evaluated a Discriminant Function Analysis (DFA) to provide a model for predicting pregnant and non-pregnant dugongs. Cross-validated results showed that the DFA correctly classified 100% of pregnant and non-pregnant females using fP concentrations, body length, fineness ratio (an index of body shape), and teat length (a female reproductive trait). Using the DFA model, we classified the pregnancy status of all female dugongs and identified a total of 30 females as pregnant and 133 females as non-pregnant from the sampled population over the sample period. Pregnant dugongs in the Moreton Bay population are characterized by fecal progesterone metabolite concentrations>1000ng/g, body length>=260cm, maximum girth>=215cm, anal girth>=126cm, and teat length>=5cm long. In summary, analysis of fP concentrations in combination with body morphometrics may be used to diagnose pregnancy in free-ranging dugongs, and provides a new tool to monitor breeding rates of wild sirenian populations.
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Eigeland, Karen A.; Lanyon, Janet M.; Trott, Darren J.; Ouwerkerk, Diane; Blanshard, Wendy H.; Milinovich, Gabriel J.; Gulino, Lisa-Maree; Martinez, Emilio; Merson, Samuel D.; Klieve, Athol V.
(detail)
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2012 |
Bacterial community structure in the hindgut of wild and captive dugongs (Dugong dugon).
Aquatic Mammals 38(4): 402-411. 3 tabs. 1 fig. DOI:10.1578/AM.38.4.2012.402.
–ABSTRACT: Dugongs (Dugong dugon) are marine mammals that obtain nutrients through hindgut fermentation of seagrass, however, the microbes responsible have not been identified. This study used denaturing gradient gel electrophoresis (DGGE) and 454-pyrosequencing to profile hindgut bacterial communities in wild dugongs. Faecal samples obtained from 32 wild dugongs representing four size/maturity classes, and two captive dugongs fed on cos lettuce were screened using DGGE. Partial 16S rRNA gene profiles of hindgut bacteria from wild dugong calves and juveniles were grouped together and were different to those in subadults and adults. In captive dugongs, the absence of the dominant bacterial DNA bands identified in wild dugongs is probably dependent upon prevailing diet and other captive conditions such as the use of antibiotics. This study represents a first step in the characterisation of a novel microbial ecosystem -- the marine hindgut of Sirenia.
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Lanyon, Janet M.; Sneath, Helen L.; Long, Trevor
(detail)
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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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Hagihara, Rie; Jones, Rhondda E.; Grech, Alana; Lanyon, Janet M.; Sheppard, James K..; Marsh, Helene D.
(detail)
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2014 |
Improving population estimates by quantifying diving and surfacing patterns: A dugong example.
Marine Mammal Science 30(1): 348-366. 3 tabs. 3 figs. DOI: 10.1111/mms.12041. January 2014.
–ABSTRACT: Diving animals are available for detection from above the water when environmental conditions are favorable and the animals are near the surface. The number of animals that are unavailable for detection needs to be estimated to obtain unbiased population estimates. The current availability correction factors used in aerial surveys for the dugong (Dugong dugon) allow for variation in environmental conditions but use the average time dugongs spend near the surface (i.e., constant availability corrections). To improve availability estimates, we examined location and dive data from nine dugongs fitted with satellite telemetry units and time-depth recorders (TDRs) in eastern Australia. The effects of water depth, tidal conditions, and habitat types on dugong surfacing time were examined using generalized linear mixed models (GLMMs). We found that availability for detection differed with water depth, and depth-specific availability estimates were often lower than the constant estimates. The habitat effect was less influential, and there was no tidal effect. The number of dugongs estimated using depth-specific availabilities were higher than those obtained using constant availabilities across water depth. Hence, information on water depth can refine availability estimates and subsequent abundance estimates from dugong aerial surveys. The methodology may be applicable to other aquatic wildlife.
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Horgan, Patrick; Booth, David; Nichols, Cassandra; Lanyon, Janet M.
(detail)
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2014 |
Insulative capacity of the integument of the dugong (Dugong dugon): thermal conductivity, conductance and resistance measured by in vitro heat flux.
Marine Biology 161(6): 1395-1407. 3 tabs. 3 figs. DOI: 10.1007/s00227-014-2428-4. April 1, 2014.
–For comments, see Owen et al. (2015) and Lanyon et al. (2015.
ABSTRACT: Extant sirenians are restricted to warm waters, presumably due to their low metabolism and poor thermoregulatory capacity, including thin blubber. When subjected to winter waters, Florida manatees (Trichechus manatus latirostris) migrate to warm areas, but dugongs (Dugong dugon) do not and instead live year-round in winter waters as cool as 15–18 °C. Dugongs appear to be more active than manatees and may have higher metabolic rates, but little is known about thermal energetics or the insulative properties of their integument. This study investigated the physical and thermal properties of whole samples of dugong integument, i.e. epidermis, dermis and hypodermis (blubber) sampled from fresh dugong carcasses collected from 2004 to 2012 in Moreton Bay (27.21°S, 153.25°E). Physico-chemical properties (thickness, density and lipid content) of each component tissue layer were measured. Thermal conductance (C) and conductivity (k) were measured for each tissue layer through in vitro temperature flux experiments within an insulated chamber. C and k were higher for dermis (25.7 ± 1.2 W m?2 K?1, 0.43 ± 0.02 W m?1 K?1, respectively, n = 21) than blubber (24.3 ± 2.4 W m?2 K?1, 0.31 ± 0.01 W m?1 K?1, n = 21), suggesting that blubber, with higher density and lipid content, affords better insulation. However, because the dermis contributes 65 % of integumentary thickness, both layers contribute significantly to insulation. The integument of dugongs is a poorer insulator compared to many cold-water marine mammals, but the greater thickness of its dermal layer means that despite its relatively thin blubber, its integumentary insulation is similar to warm-water dolphins of similar body size.
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Lanyon, Janet M.; Burgess, Elizabeth A.
(detail)
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2014 |
Methods to examine reproductive biology in free-ranging, fully-marine mammals.
Reproductive Sciences in Animal Conservation (New York, Springer) 753: 241-274. DOI: 10.1007/978-1-4939-0820-2-11. June 26, 2014.
–ABSTRACT: Historical overexploitation of marine mammals, combined with present-day pressures, has resulted in severely depleted populations, with many species listed as threatened or endangered. Understanding breeding patterns of threatened marine mammals is crucial to assessing population viability, potential recovery and conservation actions. However, determining reproductive parameters of wild fully-marine mammals (cetaceans and sirenians) is challenging due to their wide distributions, high mobility, inaccessible habitats, cryptic lifestyles and in many cases, large body size and intractability. Consequently, reproductive biologists employ an innovative suite of methods to collect useful information from these species. This chapter reviews historic, recent and state-of-the-art methods to examine diverse aspects of reproduction in fully-aquatic mammals.
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Merson, Samuel D.; Ouwerkerk, Diane; Gulino, Lisa-Maree; Klieve, Athol V.; Bonde, Robert K.; Burgess, Elizabeth A.; Lanyon, Janet M.
(detail)
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2014 |
Variation in the hindgut microbial communities of the Florida manatee, Trichechus manatus latirostris over winter in Crystal River, Florida.
FEMS Microbiology Ecology 87(3): 601-615. 5 tabs. 5 figs. DOI: 10.1111/1574-6941.12248. Mar. 2014.
–ABSTRACT: The Florida manatee, Trichechus manatus latirostris, is a hindgut-fermenting herbivore. In winter, manatees migrate to warm water overwintering sites where they undergo dietary shifts and may suffer from cold-induced stress. Given these seasonally induced changes in diet, the present study aimed to examine variation in the hindgut bacterial communities of wild manatees overwintering at Crystal River, west Florida. Faeces were sampled from 36 manatees of known sex and body size in early winter when manatees were newly arrived and then in mid-winter and late winter when diet had probably changed and environmental stress may have increased. Concentrations of faecal cortisol metabolite, an indicator of a stress response, were measured by enzyme immunoassay. Using 454-pyrosequencing, 2027 bacterial operational taxonomic units were identified in manatee faeces following amplicon pyrosequencing of the 16S rRNA gene V3/V4 region. Classified sequences were assigned to eight previously described bacterial phyla; only 0.36% of sequences could not be classified to phylum level. Five core phyla were identified in all samples. The majority (96.8%) of sequences were classified as Firmicutes (77.3 ± 11.1% of total sequences) or Bacteroidetes (19.5 ± 10.6%). Alpha-diversity measures trended towards higher diversity of hindgut microbiota in manatees in mid-winter compared to early and late winter. Beta-diversity measures, analysed through PERMANOVA, also indicated significant differences in bacterial communities based on the season.
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Seddon, Jennifer M.; Ovenden, Jennifer R.; Sneath, Helen L.; Broderick, Damien; Dudgeon, Christine L.; Lanyon, Janet M.
(detail)
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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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Lanyon, Janet M.; Horgan, Patrick; Booth, David; Nichols, Cassandra
(detail)
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2015 |
Reply to the comment of Owen et al. on "Insulative capacity of the integument of the dugong (Dugong dugon): thermal conductivity, conductance and resistance measured by in vitro heat flux" by Horgan, Booth, Nichols and Lanyon (2014).
Marine Biology DOI: 10.1007/s00227-015-2641-9. Mar. 15, 2015.
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Lanyon, Janet M.; Wong, Arthur; Long, Trevor; Woolford, Lucy
(detail)
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2015 |
Serum biochemistry reference intervals of live wild dugongs (Dugong dugon) from urban coastal Australia.
Veterinary Clinical Pathology DOI: 10.1111/vcp.12249. Publ. online April 3, 2015.
–ABSTRACT: Background: Little is known about the baseline clinical pathology of the dugong (Dugong dugon), a vulnerable marine mammal found in tropical coastal marine systems. Objectives: The purpose of the study was to collect and determine reference intervals (RI) for select serum biochemical variables for dugongs, and to analyze differences between males and females and different age groups. Methods: Reference intervals were established from 103 apparently healthy, wild-caught dugongs for 31 analytes using a Beckman Coulter AU400 Automated Chemistry Analyzer and an Olympus AU680 Chemistry-Immuno Analyzer. Results: Significant differences (P<.05) in some of the variables were found related to size class, sex, and pregnancy status. Adult dugongs had higher serum sodium, potassium, bicarbonate, glucose, and l-lactate concentrations and higher anion gap, compared to sub-adults. Male dugongs had higher triglyceride and l-lactate concentrations than females. Pregnant females displayed higher l-lactate levels compared to nonpregnant animals. Statistical differences in variables within the population contributed to better understanding of the physiologic differences between cohorts. Some serum biochemistry changes observed in this study here also potentially include some effects of pursuit on dugongs (e.g., higher l-lactate); however, as all dugongs were subject to similar capture and handling, serum biochemistry RI should be considered as normal for captured dugongs. Conclusions: The serum biochemical RI documented here are considered representative of a population of healthy captured dugongs. They provide a baseline for health surveillance of this and other dugong populations.
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Woolford, Lucy; Franklin, C.; Whap, T.; Loban, F.; Lanyon, Janet M.
(detail)
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2015 |
Pathological findings in wild harvested dugongs Dugong dugon of central Torres Strait, Australia.
Diseases of Aquatic Organisms 113(2): 89-102. 2 tabs. 9 figs. DOI: 10.3354/dao02825. Mar. 9, 2015.
–ABSTRACT: The dugong Dugong dugon is classified as Vulnerable to extinction but may be endangered in some regions. Cause of death in stranded dugongs has not been determined in a large proportion of animals examined, with investigations hindered by limited information on dugong health and diseases, and paucity of knowledge of common or endemic pathological findings. Here we describe pathological findings in harvested dugongs from the relatively pristine area of central Torres Strait, and we characterise lesions attributable to drowning. Other recorded lesions were mild and predominated by host reaction to the presence of trematodes within the gastrointestinal tracts, liver and pancreas. Ascarid worm burdens were low in comparison to dugongs from developed coastlines. Hepatocellular lipofuscin and ferritin pigmentation were commonly observed, more pronounced in livers of older animals and concurrent with periportal and bridging fibrosis. Lesions attributable to drowning included incomplete collapse of lungs, dorsal or diffuse pulmonary congestion, mild intra-alveolar haemorrhage and oedema, mild interstitial oedema and rupture of peripheral alveolar septae with acute myofibre fragmentation and degeneration. No accumulation of foam or aspiration of water or particulate matter was observed, suggesting that dugongs 'dry drown'. Morphometric features of normal spleen are also presented. Characterisation of common pathological findings and those attributable to drowning in this species will aid in the interpretation of post mortem findings for the significant number of dugongs found deceased along urbanised coastlines.
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Woolford, Lucy; Wong, Arthur; Sneath, Helen L.; Long, Trevor; Boyd, Susan P.; Lanyon, Janet M.
(detail)
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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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Hunter, Margaret E.; Meigs-Friend, Gaia; Ferrante, Jason A.; Takoukam Kamla, Aristide; Dorazio, Robert M.; Keith Diagne, Lucy; Luna, Fabia; Lanyon, Janet M.; Reid, James P.
(detail)
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2018 |
Surveys of environmental DNA (eDNA): a new approach to estimate occurrence in Vulnerable manatee populations.
Endangered Species Research 35: 101-111. doi:10.3354/esr00880. Mar. 13, 2018.
–ABSTRACT: Environmental DNA (eDNA) detection is a technique used to non-invasively detect cryptic, low density, or logistically difficult-to-study species, such as imperiled manatees. For eDNA measurement, genetic material shed into the environment is concentrated from water samples and analyzed for the presence of target species. Cytochrome b quantitative PCR and droplet digital PCR eDNA assays were developed for the 3 Vulnerable manatee species: African, Amazonian, and both subspecies of the West Indian (Florida and Antillean) manatee. Environmental DNA assays can help to delineate manatee habitat ranges, high use areas, and seasonal population changes. To validate the assay, water was analyzed from Florida's east coast containing a high-density manatee population and produced 31564 DNA molecules l-1 on average and high occurrence (?) and detection (p) estimates (? = 0.84 [0.40-0.99]; p = 0.99 [0.95-1.00]; limit of detection 3 copies µl-1). Similar occupancy estimates were produced in the Florida Panhandle (? = 0.79 [0.54-0.97]) and Cuba (? = 0.89 [0.54-1.00]), while occupancy estimates in Cameroon were lower (? = 0.49 [0.09-0.95]). The eDNA-derived detection estimates were higher than those generated using aerial survey data on the west coast of Florida and may be effective for population monitoring. Subsequent eDNA studies could be particularly useful in locations where manatees are (1) difficult to identify visually (e.g. the Amazon River and Africa), (2) are present in patchy distributions or are on the verge of extinction (e.g. Jamaica, Haiti), and (3) where repatriation efforts are proposed (e.g. Brazil, Guadeloupe). Extension of these eDNA techniques could be applied to other imperiled marine mammal populations such as African and Asian dugongs.
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Meyer, Wynn K.; Jamison, Jerrica; Richter, Rebecca; Woods, Stacy E.; Partha, Raghavendran; Kowalczyk, Amanda; Kronk, Charles; Chikina, Maria; Bonde, Robert K.; Crocker, Daniel E.; Gaspard, Joseph; Lanyon, Janet M.; Marsillach, Judit; Furlong, Clement E.; Clark, Nathan L.
(detail)
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2018 |
Ancient convergent losses of Paraoxonase 1 yield potential risks for modern marine mammals.
Science 361(6402): 591-592. doi:10.1126/science.aap7714. Aug. 10, 2018.
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Wong, Arthur; Lanyon, Janet M.; McKee, Sara J.; Linedale, Richard; Woolford, Lucy; Long, Trevor; Leggatt, Graham R.
(detail)
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2018 |
Development of a polyclonal anti-dugong immunoglobulin G (IgG) antibody with evaluation of total plasma IgG in a living dugong (Dugong dugon) population.
Veterinary Immunology & Immunopathology 200: 16-25. 2 tabs. 4 figs. DOI: 10.1016/j.vetimm.2018.04.003 Apr. 8, 2018.
–ABSTRACT: Species-specific antibodies (Ab) for the measurement of immunoglobulins (Ig) are valuable tools for determining the humoral immune status of threatened and endangered wildlife species such as dugongs. However, no studies have reported antibody reagents against dugong immunoglobulin. The object of this study was to develop an Ab with specificity for dugong IgG and apply this tool to survey total IgG levels in plasma samples from a live wild population of dugongs in southern Queensland, Australia. Dugong IgG was isolated from plasma by protein A/G column chromatography and a polyclonal antiserum was successfully raised against the dugong IgG through immunization of mice. The anti-dugong antiserum was reactive with dugong serum but not immunoglobulin from other species such as rats and humans. When tested against a panel of dugong plasma samples, relative IgG levels from dugongs (n?=?116) showed biologically relevant relationships with pregnancy status and a principal component of Body Mass Index (BMI)/globulin/fecal glucocorticosteroid (chronic stress) levels combined, which together accounted for 9.2% of the variation in total Ig levels. Together these data suggest that dugongs show variation in total IgG and that this correlates with some physiological parameters of dugong health.
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Wong, Arthur; Lanyon, Janet M.; O'Handley, Ryan; Linedale, Richard; Woolford, Lucy; Long, Trevor; Leggatt, Graham R.
(detail)
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2019 |
Serum antibodies against Toxoplasma gondii and Neospora caninum in southeast Queensland dugongs.
Mar. Mamm. Sci. https://doi.org/10.1111/mms.12629. Jan. 2020; publ. online June 24, 2019.
–ABSTRACT: The dugong (Dugong dugon) is an herbivorous marine mammal that inhabits tropical inshore waters and thus may be vulnerable to pollutants and terrestrial pathogens as a result of coastal runoff. In this study, serum samples collected from live, wild dugongs (n = 114) in an embayment located on the urbanized southeast Queensland coast of Australia during 2008–2014, were measured for IgG antibody levels specific to Toxoplasma gondii and Neospora caninum. An ELISA used to measure T. gondii tachyzoite antibodies indicated a non-Gaussian distribution of antibody level, with five dugongs identified as high outliers. Mean levels of antibodies specific for T. gondii in dugongs sampled in 2014 were significantly higher than in 2010 (p=.006) and 2011 (p=.009) with an elevation in mean antibody levels after a major 2011 flood event relative to antibody levels prior to the flood (p<.0001). A competitive ELISA to detect N. caninum antibody indicated a normal distribution of antibody with no high outliers. Mean antibody level for N. caninum was highest in 2012 and declined significantly in 2014 (p=.004). This is the first survey of antibodies directed against T. gondii and N. caninum in dugongs and suggests future health monitoring of this species.
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Smoll, L. I.; Beard, L. A.; Lanyon, Janet M.
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2020 |
Osmoregulation and electrolyte balance in a fully marine mammal, the dugong (Dugong dugon).
Jour. Comp. Physiol. B 190: 139-148. 4 tabs. 1 fig. doi: 10.1007/s00360-019-01250-8. Publ. online Jan. 1, 2020.
–ABSTRACT: Dugongs (Dugong dugon) are fully marine mammals that live independently of fresh water so must balance water and electrolytes in a hyperosmotic environment. To investigate osmoregulation, matched plasma and urine from 51 live wild dugongs were analysed for osmolality, major electrolytes (Na+, Cl-, K+), urea, creatinine, and glucose. Maximum urine osmolality (1468 mOsm kg -1) and Na+, K+, and Cl- concentrations (757, 131.3, 677 mmol L-1, respectively) indicate that dugongs are capable of concentrating urine above seawater and could potentially realise a net gain of free water from drinking seawater. However, mean urine osmolality of 925.4 (±?46.6) mOsm kg-1 suggests that mariposia is unlikely to be an important osmoregulatory mechanism. Dugongs may obtain enough preformed water from their seagrass diet and metabolic oxidation to maintain homeostasis. Mean plasma osmolality of 339.6 (±?1.8) mOsm kg-1 is higher than in the related manatees but within the range for fully marine cetaceans. Relatively high mean plasma Na+ (175.5?±?1.7 mmol L-1) and K+ (6.9?±?0.1 mmol L-1), as well as mean urinary Na+ (469.6?±?22.5 mmol L-1) and K+ levels (32.5?±?4.5 mmol L-1) may reflect a salt-rich seagrass diet. Pregnant females had higher mean plasma osmolality (355.3?±?4.9 mmol L-1) than non-pregnant females and males (337.9?±?1.7 mOsm kg-1), suggesting that fluid retention was not a feature of pregnancy. Further research on water intake and endocrinology will enhance our understanding of osmoregulation in dugongs.
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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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Lanyon, Janet M.; Sneath, Helen L.; Long, Trevor; Blanshard, Graham A. J. Worthy, David T. Booth
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2024 |
How much seagrass does a dugong need? Metabolic rate of live wild dugongs, Dugong dugon, determined through indirect calorimetry (oxygen consumption).
Mar. Mamm. Sci. https://doi.org/10.1111/mms.13190 7 figs., 5 tables. Oct. 4, 2024.
–ABSTRACT: Deterioration of seagrass beds worldwide has raised concern about the future of dugongs because almost all aspects of their life history depend on availability of seagrass. Understanding their energy metabolism and consequently how much seagrass they need will inform protective conservation strategies for dugongs. This study determined resting metabolic rate (RMR) in five wild-caught adult dugongs by measuring oxygen consumption (O2). Measurement conditions met assumptions for RMR, except that dugongs were not postabsorptive, thus a postprandial (pp) allometric equation for herbivorous mammals of similar size was used to predict an expected RMRpp for dugongs of known mass. O2 was measured for 30 min. in a metabolic tank after brief habituation. Dugongs' RMRpp was approximately half that predicted for their body mass but was higher than for manatees. Based on dugongs' RMRpp and considering plant caloric and water content, the daily minimum intake of fresh weight seagrass was 40?65?kg Halophila ovalis, or 20?40?kg Halodule spp. Greater seagrass intake would be required for growing and reproducing dugongs. Slow growth and protracted reproductive rates of dugongs are likely related to limitations in seagrass energy and nutrients. To ensure viability of this vulnerable species, it is critically important to conserve extensive healthy seagrass beds.
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Smoll, Laetitia I, Keeley,Tamara , Burgess, Elizabeth A. Lanyon, Janet M.
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2024 |
Measuring steroid hormone levels in the skin of free-ranging dugongs: A less invasive way to determine reproductive status.
Marine Mammal Science https://doi.org/10.1111/mms.13206. Nov. 22, 2024.
–ABSTRACT: Monitoring hormone concentrations in marine mammals provides valuable information regarding reproductive status and health. Skin is potentially useful for measuring hormone levels and can often be collected without capture. We investigated whether progesterone, testosterone, and cortisol could be measured in skin from dugongs using enzyme immunoassays. Hormones were measured in dorsal skin scrapings from free-ranging dugongs, including known pregnant females, nonpregnant adult females, reproductively active males, and reproductively inactive males, each identified using fecal progesterone or testosterone concentrations. Progesterone could be detected reliably in skin, with significantly higher mean progesterone concentrations (118.2 ? 6.6 ngg-1) in pregnant females than all other groups (60.8 ? 4.2 ngg-1). Male dugongs had higher skin testosterone concentrations than females, although testosterone levels were not detectable in some samples and could not discriminate reproductively active from inactive males. Cortisol was detectable in 8 of 40 skin samples only. Although refinement of this method is required for improved hormone recovery and additional validation is warranted, our findings demonstrate proof of concept for the use of epidermal skin samples to measure steroid hormones in dugongs and offer a method of diagnosing pregnancy in dugongs without the need for capture.
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Bibliography and Index of the Sirenia and Desmostylia 