Mass Occurrence of Tadpole Deformities in Toad Species of the Genus <i>Duttaphrynus</i> (Bufonidae) in the Himalaya (Uttarakhand, India)

Abstract

In April and May 2019, we examined seven tadpole samples of two bufonid species Duttaphrynus stomaticus (one site) and Duttaphrynus himalayanus (six sites) taken in the Yamuna River and its tributaries, and the Bhagirathi River at altitudes from 687 m up to 2448 m above sea level; the western part of the Garhwal Himalaya, Uttarakhand, India. Seven categories of larval deformities were recorded: scoliosis, kyphosis, shortened tail, rounded tip of the tail, bifurcated tip of the tail, opercular chamber defect, and edema. The occurrence of malformed tadpoles calculated from a sample size ranged from 3.3 to 13.6%. Water mineralization levels were fluctuated in the limits 37 – 330 mg/dm3, exceeding 100 mg/dm3 in three cases. There was no significant correlation between share of abnormal animals or abnormalities frequency and mineralization as well as with altitude. Mass occurrence of malformed tadpoles was revealed in two places: the Aglad Nadi (= Algar River, 10%, site 1, 687 m) and the town Purola (9.9 – 11.8%, sites 2 and 3, 1339 – 1349 m). Both places were associated with human activity: cattle grazing and residential agrolandscape, respectively. Enlarged rate of anomalies on the town territory may be explained by a synergy between complex of drivers (mineralization, fertilizers and pesticides) that can lead to amplification of general impact on larval morphogenesis. Thus, we reported the first record of mass larval abnormalities in amphibians for the Garhwal in particular and for the Himalaya in general. Formerly published data evidenced that another malformation hotspot of amphibians was situated at the Western Ghats, peninsular India.