From declines to defenses: Exploring trematode impacts and future research directions for Sri Lankan amphibians

Amphibians are rapidly declining worldwide, and Sri Lanka is no different. This review attempts a wholistic synthesis on the many ways in which cercarial infections interact with amphibians in Sri Lanka, and provides some pointers for future scientific studies and conservation initiatives that can help reduce the detrimental effects of parasitism on these immensely variable constituents of ecosystems. Malformations in amphibian species are widely recognized as prominent indicators of cercarial damage, as evidenced by field surveys and laboratory investigations conducted globally. This review discusses the effects of cercariae in amphibians and provide evidence supporting multiple parasite-mediated processes shaping host biology. It additionally explores host-parasite defence strategies in amphibians as parasticim and evolutionary arms-race and a pattern of co-evolution between parasites and their hosts. The review, based upon these findings, offers critical management and conservation actions for the long-term protection of the threatened Sri Lankan amphibian populations. This approach illuminates the genuine challenges to interpreting the contribution of trematode infections toward amphibian population declines and highlights future directions required for successful conservation action.