Meeting Abstract
Amphibians are animals that are closely associated with both aquatic and terrestrial habitats, what makes them vulnerable to different habitats modifications. Among those modifications, those caused by humans as fragmentation, introduction of emergent diseases, invasive species, and pollution can be highlighted as the most worrying. Pollution by trace elements can cause an impact in immune response of amphibians, depending on the amount and duration of exposure. The aim of this study was to evaluate the innate immunity of Rhinella diptycha toads at three sites with different contamination levels. Therefore, blood samples were collected to measure corticosterone plasma levels (CORT), neutrophil/lymphocyte ratio (NL) and plasma bacterial killing ability (BKA). Toads were subjected to a challenge with the mitogen phytohemagglutinin (PHA) followed by measurements of swelling response. Animals had organs collected (kidney, liver and spleen) to verify morphometric characteristics and bioaccumulation levels of trace elements specifically in the livers. The sites were divided in three levels of contamination, accordingly to the amount of trace elements found on the sediment, as follow: site 2 > site 1 > site 3. Toads from site 3 (the less contaminated) had higher levels of zinc on their livers, smaller kidneys, and larger spleens when compared to the other two sites. The toads did not presented difference among sites for CORT, NL or BKA, but toads from site 3 showed higher maximum swelling after PHA challenge. Although there is no statistical difference among sites on the main stress markers, CORT presented lower levels in toads living in the less contaminated site. These results indicate that animals living in more contaminated sites might present lower inflammatory response.
