Amphibians are important indicators of environmental health and play multiple functional roles in both aquatic and terrestrial habitats. Amphibian populations have declined worldwide and this trend has been attributed to a variety of causes, including chytridiomycosis – an infectious disease caused by the fungus Batrachotrytium dendrobatidis (Bd) – and exposure to chemical contaminants.
In Argentina, agricultural activities have increased considerably in recent years, concentrated in the country’s Pampean region. The most prevalent crop is soy, covering 72% of the country’s agricultural lands and requiring the highest pesticide use among Argentine products. Natural habitat in this region has been displaced by agricultural use, and the impacts of this transition on local ecosystems is unknown but likely significant. This project characterized species diversity, the prevalence of chytridiomycosis and malformations, and larval development in amphibians inhabiting agricultural lands in the Pampean region of Argentina as compared to control sites.
Researchers found variation in species densities between agricultural and control sites, and the complete absence of three (out of 13) species in agricultural sites, suggesting the possibility of different sensitivities to disturbance among species. Interestingly, the prevalence of chytridiomycosis was similarly high among agricultural and control sites for the four species used to detect the fungal infection. This work represented the first detection worldwide of the disease in two species of frogs, as well as the first detection in Argentina for a third species. Pond water samples were also analyzed for pesticides, revealing the presence of three separate compounds in agricultural sites and no compounds in control sites. The frequency of nine different morphological malformations was significantly higher in agricultural ponds, and for two species, the extent of malformations was more extreme. In addition, studies of larval development showed evidence in agricultural ponds of smaller clutch size, lower weight and smaller size at metamorphosis, and drastically lower survival rates as compared to control ponds.
This research team invested significant effort into community outreach, developing and distributing a field guide and conducting workshops at local schools. They also involved local communities in the collection of frogs found dead on their properties and in the fields, providing collection kits and training. These collections are especially valuable to the research effort because they allow for more extensive analyses, given that all other research is conducted using non-lethal sampling techniques. CREOi has renewed funding to continue this project during 2011-12. ($5,200)