Testing eDNA Sampling Approaches in Tropical Waterways for Citizen Science and Conservation Applications

ABSTRACT Citizen science is increasingly popular but requires training and modifications to sampling procedures so that volunteer‐collected environmental DNA (eDNA) samples can be included in biodiversity surveys. In this study, we optimised methodology for a citizen science project targeting fish taxa; ensuring simple, safe and effective eDNA sampling. We compared species richness and composition of fish eDNA data obtained from a single type of passive sampler with that obtained from Longmire's preserved water samples at three waterways in north Queensland, Australia. The results showed substantial differences in richness and species composition between the two sampling approaches assessed using cytochrome c oxidase subunit I (COI) and mitochondrial 16S assays. Longmire's preserved water samples resulted in higher read abundances and greater richness for both assays. The fish composition differed between the two sampling approaches, despite identical sampling locations and times. This study demonstrates how two different sampling and preservation approaches can lead to different fish detection results in tropical aquatic systems.