Diagnosing pregnancy in free-ranging dugongs using fecal progesterone metabolite concentrations and body morphometrics: A population application

Burgess, Elizabeth A., Lanyon, Janet M., Brown, Janine L., Blyde, David and Keeley, Tamara (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. doi:10.1016/j.ygcen.2012.02.008

Author Burgess, Elizabeth A.
Lanyon, Janet M.
Brown, Janine L.
Blyde, David
Keeley, Tamara
Title Diagnosing pregnancy in free-ranging dugongs using fecal progesterone metabolite concentrations and body morphometrics: A population application
Journal name General and Comparative Endocrinology   Check publisher's open access policy
ISSN 0016-6480
Publication date 2012-05-01
Year available 2012
Sub-type Article (original research)
DOI 10.1016/j.ygcen.2012.02.008
Open Access Status
Volume 177
Issue 1
Start page 82
End page 92
Total pages 11
Place of publication Maryland Heights United States
Publisher Academic Press
Language eng
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 enzymeimmunoassay, 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 ∼30-fold higher in confirmed pregnant dugongs (2017-7760. ng/g) compared to presumed non-pregnant females (30-221. ng/g), juvenile females (29-195. ng/g), and males (24-261. ng/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 > 1000. ng/g, body length ≥ 260. cm, maximum girth ≥ 215. cm, anal girth ≥ 126 cm, and teat length ≥ 5 cm 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.
Keyword Dugong dugon
Fecal hormones
Body morphometrics
Monitoring Ovarian-Function
Manatee Trichechus-Manatus
Steroid Metabolites
Reproductive Status
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online: 24 February 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Biological Sciences Publications
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