engleski

Ultrasound assessment of wild olms (Proteus anguinus anguinus) in Croatia

The olm (Proteus anguinus anguinus) is a neotenous salamander species with high life expectancy and low reproductive rate, classified as vulnerable by the IUCN. Little is known about olm health and reproduction in the wild. Using ultrasound, we assessed inner organs of wild olms. Data were compared to those obtained previously in 13 captive olms at the Zoological garden of Zagreb. Two divers caught 20 olms in Rupećica, Croatia, during the breeding season in January 2017. We examined internal organs using ultrasound biomicroscopy (30-70 MHz ; Vevo 2001, Visualsonics, Canada). Examinations took 10-15 minutes per individual, after which they were released back to the wild. Body masses ranged from 9-35 g (average 24±3 g). Seventeen olms presented with well-developed gonads. We identified eleven male and six female individuals, whereas the genders of three remain undetermined. Testes and follicle diameters ranged from 1.8–3.6 mm and 0.4-0.9 mm, respectively. No pathologies were detected. Digestive tracts were well-filled ; maximal gall bladder diameters (6.0±2.1 mm, range 2.3-9.4 mm) were smaller than in the captive population (7.1±1.5 mm, range 5.0-9.2 mm), implying that the two-weekly feeding intervals in captivity may be shortened. Heart rates of wild olms were slower (24.2±2.7 vs. 42.9±4.6 bpm) compared to captive individuals. Also, gills were shorter, indicating higher oxygen concentrations in the wild. The assessment of individuals from the wild is important to identify health problems in captive individuals, improve husbandry, and understand normal reproductive development, crucial to establish backup populations and future captive breeding programs for this endangered species.

Proteus anguinus ; ultrasound ; health assessment

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