Oral Presentation Society of Environmental Toxicology and Chemistry Australasia 2021

Cadmium bioaccumulation and biodistribution during amphibian development and metamorphosis (#57)

Chantal Lanctot 1 , Paul Callaghan 2 , Tom Cresswell 2
  1. Griffith University, Southport, QLD, Australia
  2. ANSTO, Lucas Heights

Larval amphibians may be particularly susceptible to metal bioaccumulation as they can absorb dissolved ions through their skin, respiratory pathways and digestive tract. Amphibians also undergo highly complex changes during development, including the degeneration and remodelling of virtually all tissues and organs as they transition from aquatic stages to terrestrial adults. Little is currently known on how these changes affect contaminant bioaccumulation kinetics and biodistribution. Our study aims to (1) investigate the changes in cadmium (Cd) biodistribution throughout tadpole development and metamorphosis, and (2) compare Cd uptake and depuration kinetics at different stages of development. Striped-marsh frog (Limnodynastes peronii) tadpoles were exposed to dissolved 109-Cd (0.5 µg Cd/L) at different developmental stages followed by a depuration period in clean water. Live animal radiotracing and imaging techniques were used to determine Cd biokinetics and biodistribution. Whole body kinetics showed that 10% of accumulated Cd was retained through metamorphosis. Bioaccumulation kinetics were found to differ between developmental stages, with the more advanced stage (metamorphic climax) accumulating less Cd and pro-metamorphic tadpoles accumulating the most. Biodistribution also varied depending on the developmental stage at which tadpoles were exposed. Cadmium partitioned primarily within the gut and gills of tadpoles exposed during pre- and post-metamorphic stages whereas Cd in tadpoles exposed at metamorphic climax was largely partitioned in the carcass (i.e., tissues excluding the gut, gills, liver and kidneys). Results highlight the importance of considering life stages when assessing the toxicity of bioaccumulative substances, especially for species that undergo metamorphosis.