Abstract
Amphibian metamorphosis is regulated under the influence of several hormones, including glucocorticoids. It is well
documented that during critical stages of amphibian metamorphosis, exposure to environmental stressors can affect the
later physiological functions via neuro-endocrine signaling pathway. We investigated how hydrocortisone, a potential
water corticoid contaminant, could affect the pre-metamorphic stage in amphibians. We exposed tadpoles of the Asian
common toad (Duttaphrynus melanostictus Schneider, 1799) from two different clutches to 5 µg/ml hydrocortisone
solution separately for a period of 13 days. By recording tadpole body lengths as a measure of growth, we were able to
observe growth inhibitory effects of hydrocortisone. Average lengths of treated tadpoles were 3.4 mm and 3.2 mm
shorter than untreated control tadpoles respectively. By day 13, hind limbs appeared in all control tadpoles while only
15 % of treated tadpoles showed this character. Further in contrast to 50 % control tadpoles, not a single test tadpole
entered metamorphic climax, indicating that exposure to elevated levels of hydrocortisone during early larval stage in
amphibians has a negative effect on growth and developmental rate. These findings suggested that hydrocortisone,
when applied in a sustained manner during critical developmental stages, resulted in delayed development.
