Complex Organisms Must Deal with Complex Threats: How Does Amphibian Conservation Deal with Biphasic Life Cycles?

SIMPLE SUMMARY: Programs to conserve biphasic amphibians may fail if threats at different life stages are not addressed. Anthropogenic threats, such as altered hydroperiods and water pollution, exacerbate the already high natural rates of mortality at the aquatic egg and larval stage, while the terrestrial life stage is threatened by disease and habitat destruction. Threats at both of these life stages influence population viability. However, our examination of the literature suggests that studies rarely address threats to both life stages, and conservation actions rarely attempt to manage threats across the life cycle. The conservation of biphasic amphibians may thus be substantially improved by applying multiple conservation actions that deal with specific anthropogenic threats across all life stages. ABSTRACT: The unprecedented rate of global amphibian decline is attributed to The Anthropocene, with human actions triggering the Sixth Mass Extinction Event. Amphibians have suffered some of the most extreme declines, and their lack of response to conservation actions may reflect challenges faced by taxa that exhibit biphasic life histories. There is an urgent need to ensure that conservation measures are cost-effective and yield positive outcomes. Many conservation actions have failed to meet their intended goals of bolstering populations to ensure the persistence of species into the future. We suggest that past conservation efforts have not considered how different threats influence multiple life stages of amphibians, potentially leading to suboptimal outcomes for their conservation. Our review highlights the multitude of threats amphibians face at each life stage and the conservation actions used to mitigate these threats. We also draw attention to the paucity of studies that have employed multiple actions across more than one life stage. Conservation programs for biphasic amphibians, and the research that guides them, lack a multi-pronged approach to deal with multiple threats across the lifecycle. Conservation management programs must recognise the changing threat landscape for biphasic amphibians to reduce their notoriety as the most threatened vertebrate taxa globally.