PARKVILLE, Victoria -- Journal of Mammalogy – Advertisers often tell us how life-changing hair loss can be, but it actually is a matter of life and death for the Australian fur seal. These seals depend on a thick coat of fur to maintain their body temperature. Seals in the Bass Strait off southern Australia are losing clumps of their fur. Damage to this insulation means that the animals must spend more energy maintaining a core body temperature, negatively affecting their health and survival.
The current issue of the Journal of Mammalogy reports on the two-and-a-half year study of an Australian fur seal colony at Lady Julia Percy Island. Since 1989 a hair loss syndrome, or alopecia, has been particularly prevalent among this population of about 30,000 seals.
It is essential for warm-blooded mammals living in cold environments to maintain a core body temperature. It is even more challenging for species that move between land and water. Unlike sea lions, which depend on a layer of blubber for insulation, fur seals depend on a dense coat of hair.
The Australian study, conducted from September 2007 to February 2010, observed seals at several Bass Strait locations at regular intervals. Additionally, 117 seals were captured at Lady Julia Percy Island and examined for sex, age, body mass, body condition, and hair loss, then tagged and released. Diagnostic samples of hairs were taken, and the extent of alopecia on each seal was recorded using diagrams and digital photographs.
Researchers also used a thermal imaging camera to record the effects of the fur loss on surface body temperatures. With this technology, the study found a difference of 6.6 degrees Celsius (11.9 degrees Fahrenheit) between areas of the dorsal thorax affected and unaffected by alopecia. Animals experiencing hair loss were in significantly poorer body condition than those with no hair loss.
This study shows that alopecia does not affect all seals equally. Predominantly juveniles and females were affected. A seasonal pattern was noted as well. The alopecia peaked in spring and summer. Even though these seals undergo an annual molt, evidence suggests that molting does not alleviate the hair loss.
The samples and information gathered from capturing the seals are part of a continuing search for the cause of alopecia among the Bass Strait seals. The pathology of this syndrome is not yet known. Potential environmental causal factors are being investigated.
Full text of the article, "Prevalence and significance of an alopecia syndrome in Australian fur seals (Arctocephalus pusillus doriferus)," Journal of Mammalogy, Vol. 92, No. 2, April 2011, is available at: http://www.asmjournals.org/doi/full/10.1644/10-MAMM-A-203.1
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