Dr Lara Denis-roy1, Professor Graham Edgar1, Dr Katrina West2, Dr Bruce Deagle2, Professor Craig Johnson1, Dr Priscila Goncalves3, Dr Yann Herrera Fuchs1, Dr Olivia Johnson1, Matt Rose1, Dr Tyson Jones1, Laura Missen3, Marcelle Ayad3
1IMAS, Hobart, Australia, 2CSIRO, Hobart, Australia, 3Minderoo Foundation, Perth, Australia
Biography:
Lara Denis-Roy is a Postdoctoral Research Fellow at the Institute for Marine and Antarctic Studies, University of Tasmania. Her research focuses on integrating environmental DNA with established ecological survey methods to improve marine biodiversity monitoring, particularly across Australia’s temperate and tropical reef ecosystems.
Abstract:
Reef communities undergo pronounced changes between day and night as species alter their activity, behaviour and habitat use, creating an important consideration for biodiversity monitoring. Although diel variation in environmental DNA (eDNA) has been documented across aquatic systems, the extent to which molecular observations reflect corresponding changes in local communities remains variable.
We use paired eDNA metabarcoding and underwater visual surveys (UVS) from 33 tropical and temperate Australian reef sites to examine how biodiversity signals change between day and night, and whether patterns detected through eDNA correspond to those observed directly on reefs. We compare diel patterns in taxon richness and assemblage composition across survey methods and biogeographic regions.
Preliminary analyses indicate stronger day–night differentiation in visual surveys than in eDNA, with responses also varying between tropical and temperate reef systems. Building on these patterns, we investigate within-site changes in community composition and taxon-level diel detection patterns to examine how closely changes in eDNA reflect corresponding changes in directly observed reef communities.
Understanding how eDNA represents short-term ecological variation is important for its application in large-scale biodiversity monitoring. By comparing molecular signals against simultaneous ecological observations across a broad geographic range, this study examines how sampling time and biogeographic context influence the biodiversity represented by eDNA and how these factors should be considered when designing marine eDNA monitoring programs.