CQUniversity Australia - Khurshida Akter Siddiqua

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Research Details

Thesis Name: Assessment of atrazine toxicity to the cane toad (Bufo marinus): a multigenerational approach and the potential as a novel laboratory test animal

Thesis Abstract:

Global amphibian declines have been of great concern over recent years due to a number of increasing natural and anthropogenic stressors. Reproductive and developmental abnormalities in amphibians have been reportedly linked to pesticide exposures and atrazine is one such pesticide that is of particular concern. Studies have shown gonadal deformities in frogs exposed to atrazine concentrations as low as 0.1µg/ L. The majority of amphibian toxicity tests used worldwide has been conducted using the African clawed frog, Xenopus laevis, or a species of Rana, Hyla, or Bufo. In contrast, the use of Australian native frogs in toxicity testing is very limited. Differences in susceptibility to environmental contaminants may exist between Australian amphibians compared to overseas frog species. Atrazine is one of the most widely applied herbicides and is commonly detected in surface and groundwater samples in Australia.

Why my research is important/Impacts:

The role of amphibians as a major herbivore (tadpole phase) and a predator (adult phase) suggest that frogs are important to ecosystem dynamics and being sensitive to environmental contaminants makes them a potential sentinel organism for determining environmental health. The extensive use of atrazine which often coincides with breeding season of frog species and subsequent prevalence in aquatic environments indicates a risk to frog populations. Local toxicity data on atrazine is scarce despite increasing attention overseas due to the contradicting results of atrazine toxicity to amphibians. Moreover, there is a lack of toxicity data on native frogs in Australia. It is hoped that these research outcomes will add informative data in this regard and thus will be helpful for agricultural environment management in Australia as well as in developing strategies and management actions for the benefit of amphibians and other animals, ultimately for our own good. The Australian Pesticides and Veterinary Medicines Authority (APVMA) has reviewed atrazine several times because of its great concern on human health, amphibian reproductive abnormalities, and also for frequent detection in surface and ground waters, but most of the reviews were based on overseas studies. So it is also hoped that informative data from this study will be helpful in reviewing atrazine by using local data. This research will also investigate the suitability of cane toads as a potential laboratory test species and as a surrogate organism to native frog species. And for this purpose, tadpoles of both cane toad and native striped marsh frog have been exposed to the same atrazine treatments alone and also in combination with another stressor, salinity, for 96 hours and also for 21 days as well, which can provide a broad range of comparative toxicity data on these two experimental species. These data will also be helpful in assessing the possibilities of cane toads as toxicity test animals.

Funding/Scholarship: