Amphibian communities of agroecosystems in the Argentine Pampean green belt and their conservation challenges
This is a continuation of a previously funded project (2010).
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 – and exposure to chemical contaminants.
In Argentina, agricultural activities – including high pesticide use – have increased considerably in recent years, concentrated in the country’s Pampean region. 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, larval development and the prevalence of chytridiomycosis and malformations in amphibians inhabiting agricultural lands as compared to control sites.
The study found higher species richness in control versus agricultural sites, though this difference was not statistically significant. Measures of relative abundance were more conclusive, demonstrating higher abundance in all control sites relative to agricultural sites. Those cultivated sites that were most isolated from non-agricultural habitat had the lowest abundances of all. Abundance was also negatively correlated with chemical contaminants measured in ponds at all sites – control sites (with higher amphibian abundance) had fewer compounds and lower concentrations of those compounds that were detected.
The prevalence of adult malformations was significantly higher in cultivated sites relative to control sites, though the prevalence at control sites was still higher than baseline rates published for other populations in natural habitats, suggesting some degree of local contamination of control sites by nearby agricultural activities. Similarly, disruptions to larval development were evident on cultivated lands. Of the 19 cycles observed during the study, 15 cycles showed higher larval malformation in agricultural ponds than in control ponds. Interestingly, the incidence of the fungus causing chytridiomycosis was higher at control sites than at agricultural sites, a finding that will require further analysis to explain.
This research team also increased their already high investment in community outreach. The previously developed field guide was enhanced and accepted by University of La Plata Press for publication of 1,000 copies. A diversity of delivery tools was used to match the different communities in the area. For example, a Facebook page and other social media approaches targeted the younger, computer-literate population. School workshops continued to teach children about local biodiversity and the effects of pesticides. Meanwhile, a focus remained on community presentations and dozens of home visits tailored to the farmworker families who are predominantly illiterate. ($6,710)