Effects of water acidification and pathogen exposure on innate immunity in Cuban tree frog (Osteopilus septentrionalis) tadpoles

Freshwater acidification, an issue largely linked to industrialization and human activity, threatens freshwater environments and the organisms that inhabit them. The combination of acidification and additional stressors already present in freshwater may increase the threat. We exposed Cuban tree frog (Osteopilus septentrionalis) tadpoles to acidified water and Aeromonas hydrophila, a common water bacterium and amphibian pathogen. We monitored development, growth, and immune defense among tadpoles from different treatments, and performed bacterial killing assays on whole blood samples from these tadpoles. We found that neither acidity nor pathogen exposure, nor a combination of the two, had a statistically significant effect on immune defense in O. septentrionalis, as measured by A. hydrophila killing ability, when considering varying Gosner developmental stages and snout-to-vent lengths. There was a trend toward reduced bacterial killing ability in animals receiving any of the stressors compared to those in the control group. Our results could hold implications for the future of native species as a result of increased tolerance to environmental stressors in this invasive species.

Keywords: Innate Immunity, Amphibian, Acid Rain, Toxicology.