Tadpoles as Bioindicators of Aquatic Ecosystem Health: A Systematic Review of Water Quality and Land Use Interactions on Tadpole Assemblages
TL;DR
Results indicate that agricultural expansion and urbanization modify breeding habitats, reduce tadpole density and increase malformation rates, whereas water quality stressors, including eutrophication, contaminant loading and hydroperiod variability, were consistently linked to developmental abnormalities.
Abstract
Amphibian populations are in global decline, with 41% of species considered threatened, driven by habitat loss, land use change, climate change and diseases, particularly chytridiomycosis. Larval stages are confined to aquatic environments making tadpoles reliable bioindicators of ecosystem health due to high sensitivity to both water quality and surrounding land use. This systematic review synthesizes evidence from 58 studies published between 2005 and 2025 that examined the effects of land use and water quality characteristics on anuran tadpole assemblages. Following PRISMA 2020 guidelines, a structured literature search was conducted across Web of Science, Scopus and Google Scholar in December 2025. Studies were synthesized narratively across four thematic objectives: (i) land use effects on breeding habitat suitability, (ii) water quality and pollutant exposure, (iii) tadpole density and breeding pool dynamics and (iv) tadpole deformities and sublethal effects. Results indicate that agricultural expansion and urbanization modify breeding habitats, reduce tadpole density and increase malformation rates, whereas water quality stressors, including eutrophication, contaminant loading and hydroperiod variability, were consistently linked to developmental abnormalities. These findings highlight the importance of breeding habitat management for amphibian conservation. We recommend prioritizing protection and restoration of natural ponds, mitigating agricultural runoff and standardizing monitoring protocols. This synthesis provides a framework for conservation strategies and identifying key research gaps in amphibian larval ecology.