Integrity Matters: Riparian Forest Preservation Influences Body Condition and Parasites of Amphibians

Aline Aguiar, Alison Wunderlich, Lucas Henrique dos Santos, Drausio Honório Morais, Alba Lucia Cavalheiro, Célio F. B. Haddad

Riparian forests are essential for the structure and dynamics of head streams, performing an important role in maintaining biodiversity in fragmented forests. Integrity condition influences the stream quality and the distribution of amphibians and their responses to infections. To investigate this premise, we evaluated parasite infection parameters in amphibians through six riparian areas with different integrity levels (low, intermediate and high) in an Atlantic Forest ecosystem. We hypothesized that more preserved forest fragments (high integrity) sustain a high diversity, low abundance, and large proportion of parasite species with complex life cycles. To test this hypothesis, we described the parasite community in Proceratophrys avelinoi populations and modeled the forest traits and water abiotic factors as predictor variables on parasite parameter responses. Although the amphibians’ populations exhibited a total parasite richness of eight species, our multivariate analysis revealed that only Physalopterinae nematodes showed significant differences between forest fragments; moreover, the overall parasite abundances were affected by abiotic factors. We found that high-integrity fragments not only support parasites with complex life cycles but also improve the host's body condition. This contributes to the development of host populations with more energetic investments, which are essential to resist and tolerate infections. On the contrary, the concurrent high parasite loads and reduced body conditions observed in intermediary integrity areas may lead to a metabolic collapse that threatens long-term population decline. Our results highlight the importance of ecosystem integrity in the riparian forests for providing better resources for amphibians and in overcoming the risk of diseases by helminth parasites.